| Title of Invention | METHOD FOR PRODUCING ACRYLIC ACID FROM PROPANE |
|---|---|
| Abstract | The invention concerns a method for producing acrylic acid from propane. which consists in passing a gas mixture in. cluding propane. water vapour. and optionally an inert gas and/or molecular oxygen. on a catalyst of formula (1): Mo1 Va.Sbb.NbcSidOx wherein: a ranges between 0.006 and 1. inclusively; b ranges between 0.006 and 1. inclusively; c ranges between 0.006 and 1. in. closively; d ranges between 0 and 3.5. inclusively; and x is the amount of oxygen bound to the other elements and depends on their state of oxidation. for oxidizing propane into acrylic acid. and which is carried out in the presence of molecular oxygen, the propane/molecular oxygen inot ratio in the initial gas mixture is not less than 0.5. (57) A brégé: Procédé de fabrication d"acide acrylique à partir de propane. selon on equal on fait passer un mélange gazuex comprenant du propant,. de la vapeur d'eau. .ainsi qo'évent element gaz inert et/ou de l'oxygène moléculaire, sur un catalyseur de formule (1): Mo1VaSbbNbcSi4O1 dans lesquelles: a est compris entre 0.006 et I, bornes incluses; b est compris entre 0,006 et I, burnes incluses; c est compris entre 0,0006 et I, bornes incluses; d est compris entre 0 et 3.5, bornes incluses; et x est la quantilé d'oxyène lié sux autres élements et dépend de leurs états d'oxydation. [Suite sur la page silvante] |
| Full Text | The present invention relates to the production of acrylic acid from propane in the presence or in the absence of molecular oxygen. It is known from European patent application No. EP-A-608838 to prepare an unsaturated carboxylic acid from an alkane with a catalytic oxidation reaction, in vapour phase, in the presence of a catalyst containing a mixed metal oxide comprising 10 as essential components, Mo, V, Te, O, as well as at least one element chosen from the group constituted by niobium, tantalum, tungsten, titanium, aluminium, zirconium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, antimony, bismuth, boron, indium and cerium, these elements being present in very precise proportions. The reaction can be implemented using a 15 gaseous mixture composed of the alkane, oxygen, an inert gas and water vapour presenting the following molar proportions: alkane/oxygen/inert gas/water vapour = 1/0.1-10/0-20/0.2-70 and preferably 1/1-5/0-10/5-40. Moreover, European patent application No. EP-A-895809 describes catalysts 20 based on oxides comprising molybdenum, vanadium, niobium, oxygen, tellurium and/or antimony, as well as at least one other element such as iron or aluminium. These catalysts can be used for the conversion of propane to acrylic acid, in the presence of molecular oxygen, as illustrated in Examples 9 and 10. Example 9, in particular, describes the oxidation of propane using a catalyst having the formula 25 Mo1Vo33Nb0.11Te0.22Ou from a gas flow composed of propane, oxygen, helium and a flow of water vapour, according to a molar ratio propane/oxygen/helium/water vapour of approximately 1/3.2/12.1/143. In such a gas flow, the flow of reactive gas has a very low concentration of propane. Consequently the recycling of the unconverted propane is 30 much more difficult because this unconverted propane is too diluted in the reaction flow. The aim of the invention is to propose a process for the production of acrylic acid from propane, in the presence or in the absence of molecular oxygen, which allows a R:/Brevels/20200/20293US-22/02/05 2 higher conversion of propane to be obtained while retaining good acrylic acid selectivity. The inventors have discovered that this aim can be achieved by passing a gaseous mixture comprising propane, water vapour, as well as optionally an inert gas and/or 5 molecular oxygen, over a particular catalyst. When operating in the presence of molecular oxygen the oxidation is carried out under conditions such that the oxygen of the gaseous mixture is in a substoichiometric proportion in relation to the propane introduced, which allows the catalyst to act in a similar way to a redox system and provides the oxygen which is lacking so that the reaction is carried out in a 10 satisfactory way. The advantages of this novel process are the following: - - the limitation of the overoxidation of the products formed which takes place in the presence of too great a quantity of molecular oxygen; according to the present invention, due to the fact of operating in substoichiometry, the 15 formation of COX (carbon monoxide and carbon dioxide), degradation products, is reduced, which allows the acrylic acid selectivity to be increased; - the acrylic acid selectivity is maintained at a good level; - the conversion is increased without loss of selectivity; - the catalyst undergoes only a low reduction and therefore a small loss of its 20 activity; it can easily be regenerated by heating in the presence of oxygen or a gas containing oxygen after a certain period of use; after regeneration, the catalyst regains its initial activity and can be used in another reaction cycle; - moreover, the separation of the stages of reduction of the catalyst and of regeneration of the latter can be provided which allows the partial pressure of 25 propane to be increased, such a partial supply pressure of propane being little limited by the existence of an explosive zone created by the propane + oxygen mixture, because the later is present in molecular form in substoichiometric proportions; - moreover, this process allows reduction of the formation of products produced 30 by hydration, in particular propionic acid, acetone and acetic acid. The subject of the present invention is therefore a process for the production of acrylic acid from propane, in which a gaseous mixture containing propane, water vapour, optionally an inert gas, and/or molecular oxygen is passed over a catalyst of formula (I): 3 Mo1VaSbbNbcSidOI (I) in which: - a is comprised between 0.006 and 1, inclusive; - b is comprised between 0.006 and 1, inclusive; 5 - c is comprised between 0.006 and 1, inclusive; - d is comprised between 0 and 3.5, inclusive; and - x is the quantity of oxygen bound lo the other elements and depends on their oxidation state. in order to oxidize the propane to acrylic acid, and when operating in the presence of 10 molecular oxygen, the molar ratio propane/molecular oxygen in the initial gaseous mixture is greater than 0.5. Such a process allows an acrylic acid selectivity of close to 60 % and a high conversion of propane to be obtained simultaneously. Moreover, it can easily be implemented in a fluidized bed or in a moving bed and the injection of the reagents 15 can be carried out at different points of the reactor, so as to be outside of the flammability zone white having a high propane concentration and, consequently, a high catalyst productivity. According to a particularly advantageous embodiment, the process according to the invention comprises the following stages: 20 I/ In the absence of molecular oxygen When the initial gaseous mixture is devoid of molecular oxygen, the propane is oxidized according to the following redox reaction (A): SOLIDoxidized + PROPANE SOLIDreduced + ACRYLIC ACID (A) II/ In the presence of molecular oxygen 25 a) the initial gaseous mixture is introduced into a first reactor with a moving catalyst bed, b) at the outlet of the first reactor, the gases are separated from the catalyst; c) the catalyst is returned into a regenerator; d) optionally the gases are introduced into a second reactor with a moving 30 catalyst bed; e) if appropriate, at the outlet of the second reactor, the gases are separated from the catalyst and the acrylic acid contained in the separated gases is recovered; f) if appropriate, the catalyst is returned into the regenerator; and 4 g) the regenerated catalyst from the regenerator is reintroduced into the first reactor and, if appropriate, the second reactor; According to another advantageous embodiment of the invention, the reactor or reactors are also provided with a cocatalyst. 5 According to another advantageous embodiment of the invention, the process comprises the repetition, in a reactor provided with the catalyst of formula (I) and, if appropriate, with a cocatalyst, of the cycle comprising the following successive stages: 1) a stage of injection of the gaseous mixture as defined above; 2) a stage of injection of water vapour and, if appropriate, of inert gas; 10 3) a stage of injection of a mixture of molecular oxygen, water vapour and, if appropriate, inert gas; and 4) a stage of injection of water vapour and, if appropriate inert gas. According to an improvement of the advantageous embodiment which has just been described, the cycle comprises an additional stage which precedes or follows 15 stage 1) and during which a gaseous mixture corresponding to that of stage 1) is injected but without the molecular oxygen, the molar ratio propane/ molecular oxygen then being calculated globally for stage 1) and this additional stage. According to an advantageous embodiment of the improvement which has just been presented, the additional stage precedes stage 1) in the cycle. 20 Other characteristics and advantages of the invention will now be described in detail in the following description which is given with reference to the single attached figure which diagraraatically represents an apparatus which is suitable for the implementation of an advantageous embodiment of the process according to the invention. 25 DETAILED DESCRIPTION OF THE INVENTION According to the invention, in the alternatives where molecular oxygen is introduced, because the molar ratio propane/molecular oxygen in the initial gaseous mixture is greater than or equal to 0.5, the conversion of the propane to acrylic acid using the catalyst is carried out by oxidation, probably according to the following 30 concurrent reactions (A) and (B): - the standard catalytic reaction (B): CH3-CH2-CH3 + 2O2 CH2=CH-COOH +- 2H2O (B) - and the aforementioned redox reaction (A): SOLIDoxidzed + CH3-CH2-CH3 SOLIDreduced + CH2 = CH-COOH (A) R^rewts^DMWtfffiSOUS - jaUKW The propane/water vapour volume ratio in the initial gaseous mixture is not critical and can vary within wide limits- Similarly, the proportion of inert gas, which can be helium* krypton, a mixture of these two gasses, or nitrogen, carbon dioxide, etc., is also not critical and can also 5 vary within wide limits. The proportions of the constituents of the initial gaseous mixture are generally as follows (in molar ratios): propane/oxygen/inert (He-Kr)/H2O (vapour) = 1/0.05-2/1-10/1-10 Preferably, they are 1/0.1-1/1-5/1-5. 10 Yet more preferably, they are 1/0,167-0.667/2-5/2-5. As particularly beneficial proportions the following may also be cited: 1/0,2-0.4/4-5/4-5. Generally, reactions {A) and (B) are carried out at a temperature of 200 to 50Q°C, preferably from 250 to 450°C, yet more preferably from 350 to 400ºC, The pressure 15 in the reactor or reactors is generally from l.OlxlO4 to I,01xl06 Pa (0.1 to 10 atmospheres), preferably from 5.05xl04 to 5.05x10s Pa (0.-5 atmospheres). The residence time in the reactor, or if there are several, in each reactor* is generally from 0.01 to 90 seconds, preferably from 0,1 to 30 seconds. The catalyst corresponds to the following formula (I): 20 MoaSbbNbcSidOx, (I) in which; - a is comprised between 0.006 and 1, inclusive; - b is comprised between 0.006 and 1, inclusive; - c is comprised between 0.006 and 1, inclusive; 25 - d is comprised between 0 and 3.5, inclusive; and - x is the quantity of oxygen bound to the other elements and depends on then- oxidation state. Advantageously: - a is comprised between 0.09 and 0.8, inclusive; 30 - b is comprised between 0.04 and 0.6, inclusive; - c is comprised between 0.01 and 0.4, inclusive; and - d is comprised between 0.4 and 1.6, inclusive. The oxides of the different metals included in the composition of the catalyst of formula (1) can be used as raw materials in the preparation of this catalyst, but the raw R:/Brevels/20200/20293US-22/02/05 materials are not limited to the oxides; among the raw materials which can be used there may be mentioned, as non-limitative examples: - in the case of molybdenum, ammonium molybdate, ammonium paramolybdate, ammonium heptarnolybdate, molybdic acid, molybdenum 5 halides or oxyhatides such as M0Cl5, organometallic compounds of molybdenum such as molybdenum alkoxides such as Mo(OC2H5)5, acetylacetone molybdenyl; - in the case of vanadium, ammonium metavanadate, vanadium halides or oxyhalides such as VC4, VC5 or VOCl3, organometallic compounds of 10 vanadium such as vanadium alkoxides such as VO(OC2H5)3; - in the case of antimony for example antimony oxide (antimony trioxide), in particular of the senannontite variety, antimony trisulphate, (Sb2SO4)3 or an antimony cnloride (antimony trichloride, antimony pentachloride); - in the case of niobium, niobic acid, niobium tartrate, niobium hydrogen 15 oxaiate, oxotrioxalatoammonium niobate {(NH4[NbO(C2O4)]l.5H2O} niobium and ammonium oxalate, niobium oxalate and tartrate, niobium nalides or oxyhalides such as NbCl3, NbCl5 and organometallic compounds of niobium such as niobium alkoxides such as Nb(OC2H5)5, Nb(O-n-Bu)5; and, generally,, all the compounds which are able to form an oxide by calcination, 20 namely, the metallic salts of organic acids, the metallic salts of mineral acids, the metal complex compounds, etc. The source of silicon is generally constituted by colloidal silica and/or polysiticic acid. According to particular embodiments, the catalyst of formula (I) can be prepared 25 by mixing aqueous solutions of niobic acid, oxalic acid, ammonium heptamolybdate, ammonium metavanadate, antimony oxide, under stirring, by the addition, if appropriate, of colloidal silica, then by precalcinating under air at a temperature comprised between 280 and 340 C preferably at approximately 300 - 320 C and by calcinating under nitrogen at approximately 600 C 30 Preferably, in the thus-prepared catalyst of formula (I): - a is comprised between 0.09 and 0.8, inclusive; - b is comprised between 0.04 and 0.6, inclusive; - c is comprised between 0.01 and 04, inclusive; and - d is comprised between 0.4 and 1 -6, inclusive. More particularly, the process for the preparation of the catalyst of formula (1) is implemented by the preparation of a solution of niobic acid, oxalic acid, preparation of a solution of molybdenum, vanadium, antimony and optionally silica, a mixture of the 2 solutions produces the formation of a get, drying of the gel obtained produces 5 the formation of a precursor of formula (I') below, precalculation then calcination. More precisely, according to a particularly preferred process, the catalyst can be prepared by implementing the following stages: 1) dissolution in water of a source of vanadium, for example, ammonium metavanadate, under stirring and optionally by heating; 10 2) addition to the previously obtained solution of a source of antimony, for example antimony oxide in particular the senarmonite variety; 3) addition of a source of molybdenum, for example, ammonium heptamolybdaie; 4) reaction of the solution obtained, under reflux; 5) addition of an oxidizing agent such as hydrogen peroxide; 15 6) if appropriate, addition of silica; 7) addition of a solution prepared by mixing, under heating, a source of niobium, for example, niobic acid, with oxalic acid; 8) reaction of the reaction mixture under reflux and preferably under inert atmosphere, until a gel is obtained; 20 drying of the gel obtained which leads to a precursor; 9) precalculation of the precursor; and 10) calcination of the precalcinated gel in order to obtain the catalyst. As a variant, instead of having three successive stages 1), 2) and 3), these stages are combined by introducing the sources of vanadium, antimony and molybdenum into 25 cold water and stirring in order to obtain a solution. Preferably, in stage 5), hydrogen peroxide is added until an orange-coloured limpid solution is obtained. In the alternative processs below: - the drying (for example of stage 9) can be carried out in an oven in a thin layer, by 30 atomtzation, freeze-drying, zeodration, with microwaves, etc, - the precalculation can be carried out under air flow at 280 - 300°C or under static air at 320°C, in a fluidized bed, in a rotary furnace in a so-called aerated fixed bed, so that the catalyst pellets are separated from each other in order to prevent them from fusing during precatcination or possibly during calcination; R:/Brevels/20200/20293US-22/02/05 8 the calcination is preferably carried out under very pure nitrogen and at a temperature close to 600°C, for example in a rotary furnace or in a fluidized bed and for a duration which can be 2 hours. The catalyst obtained at the end of the calcination can be ground in order to 5 produce smaller particles. If the grinding is continued until a powder constituted by particles of approximately the size of a micron is obtained, the powder can subsequently be returned to its form using a binding agent such as for example silica in the form of poly silicic acid, the suspension then being dried again, for example by atomrzation. 10 According to a more particularly preferred embodiment of the invention, the precalcination is carried out: - either at a temperature of less than 300ºC under an air flow of at least 10 ml/min/g of catalyst; - or at a temperature ranging from 300 to 350°C under an air flow less than 10 15 ml/min/g of catalyst. According to a particularly preferred embodiment, the precalculation is carried out: - at approximately 32O°C under an air flow less than 10 ml/min/g; or - at approximately 290°C under an air flow of approximately 50 ml/min/g. 20 Regeneration of the catalyst During the redox reaction (B), the catalyst undergoes reduction and a progressive loss of its activity. This is why, omce the catalyst has at least partially changed to the reduced state, its regeneration is carried out according to reaction (C): SOLIDreduced + O2 → SOLIDoxidized (C) 25 by heating in the presence of oxygen or a gas containing oxygen at a temperature of 250 to 500 C, for a time necessary for the reoxidation of the catalyst. The proportions of the constituents of the regeneration gaseous mixture are generally as follows (in molar ratios): oxygen/inert(He-Kr)H2O(vapour) =1/1=10/0-10 30 Preferably, they are 1/1-5/0-5. Instead of using the oxygen alone, dry air (21 % O2) can be used. Instead of or in addition to the water vapour, moist air can thus be used. The regeneration temperature is generally from 250 to 500 C. 9 Generally the process is carried out until the reduction ratio of the catalyst is comprised between 0.1 and 10 g of oxygen per kg of catalyst. This reduction ratio can be monitored during the reaction through the quantity of products obtained. Then the equivalent quantity of oxygen is calculated. It can also 5 be monitored through the exothermicity of the reaction. The reduction ratio can also be monitored through the quantity of oxygen consumed in the regenerator. After regeneration, which can be carried out under temperature and pressure conditions which are identical to, or different from those of the reactions (A) and (B), the catalyst regains an initial activity and can be reintroduced into the reactors. 10 The reactions (A) and (B) and the regeneration (C) can be carried out in a standard reactor, such as a fixed bed reactor, a fluidized bed reactor or a moving bed reactor. Thus the reactions (A) and (B) and the regeneration (C) can be carried out in a device with two stages, namely a reactor and a regenerator which operate simultaneously and in which two catalyst loadings alternate periodically. 15 The reactions (A) and (B) and the regeneration (C) can also be carried out in the same reactor by alternating the periods of reaction and regeneration. Preferably, the reactions (A) and (B) and the regeneration (C) are carried out in a reactor with a moving catalyst bed, in particular in a vertical reactor, the catalyst then preferably moving from the bottom upwards. 20 An operating process with only one passage of the gas or with recycling of the gas can be used. According to a preferred embodiment, the propylene produced and/or the propane which has not reacted are recycled (or returned) to the inlet of the reactor, i.e. they are reintroduced at the inlet of the reactor, in a mixture or in parallel with the 25 initial mixture of propane, water vapour and if appropriate inert gas or gases. Use of an apparatus with two reactors and a regenerator According to an advantageous embodiment of the invention, the process according to the invention is used in an apparatus such as the one represented in the attached 30 figure. The initial gaseous mixture comprising propane, molecular oxygen, water vapour as well as, if appropriate, an inert gas, is introduced into a first reactor (Riser 1) containing the moving catalyst bed. R:/Brevels/20200/20293US-22/02/05 10 Then, at the outlet of the first reactor, the effluents are separated into gases and the moving catalyst bed. The catalyst is sent into a regenerator. The gases are introduced into a second reactor (Riser 2) also containing a moving 5 catalyst bed. At the outlet of the second reactor, the effluents are separated into gases and the moving bed catalyst. The catalyst is sent into a regenerator. The gases are treated in a known way, generally by absorption and purification, 10 with a view to recovering the acrylic acid produced. The regenerated catalyst is reintroduced into the first reactor as well as into the second reactor. The process thus operates continuously, the circulation of the catalyst between the reactors and the regenerator is earned out in a regular and generally continuous way. 15 Of course, the single regenerator can be replaced by two or more regenerators. Moreover, it is possible to add, after the second reactor, other reactors which also have a catalyst circulating between each of these reactors and the regenerator or other regenerators. Preferably, the first and second reactors are vertical and the catalyst is transported 20 upwards by the gas flow. An operating process with only one passage of gases or with recycling of the products leaving the second reactor can be used. According to a preferred embodiment of the invention,, after treatment of the gas originating from the second reactor, the propylene produced and/or the propane which 25 has not reacted are recycled (or returned) to the inlet of the reactor, i.e. they are reintroduced at the inlet of the first reactor, in a mixture or in parallel with the initial mixture of propane, oxygen, water vapour and, if appropriate, inert gas or gases. Use of a cocatalvst According to another advantageous embodiment of the invention, the gaseous 30 mixture also passes over a cocatal yst. This has the advantage of reducing the production of propionic acid, which is generally a by-product of the conversion reaction and which poses problems in certain applications of acrylic acid when it is present in too great a quantity. R:/Brevels/20200/20293US-22/02/05 11 Thus, the prcpionic acid /acrylic acid ratio is greatly reduced at the outlet of the reactor. Moreover, the formation of acetone, which is also a by-product of the production of acrylic acid from propane, is reduced. S To this end, at least one of the reactors comprises a cocatalyst with the following formula (II): Mo1Bia-Feb'Coc'Nid'Ke'SbfTig'SihCa1'Nbj'.Tek'Pbr.Wm'.Cua' (II) in which: - a' is comprised between 0.006 and 1, inclusive; 10 b'is comprised between 0 and 3.5, inclusive; - c' is comprised between 0 and 3.5, inclusive; - d' is comprised between 0 and 3.5, inclusive; - e' is comprised between 0 and 1, inclusive; - f' is comprised between 0 and 1, inclusive; 15 g' is comprised between 0 and 1, inclusive; - h' is comprised between 0 and 3-5, inclusive; - i' is comprised between 0 and 1, inclusive; - j' is comprised between 0 and 1, inclusive; - k' is comprised between 0 and 1, inclusive; 20 l' is comprised between 0 and 1, inclusive; - m' is comprised between 0 and ], inclusive; and - n1 is comprised between 0 and 1, inclusive. Such a cocatalyst can be prepared in the same way as the catalyst of formula (I). The oxides of the different metals included in the composition of the cocataiyst of 25 formula (II) can be used as raw materials in the preparation of this cocatalyst, but the raw materials are not limited to the oxides; as other raw materials, the corresponding nitrates can be mentioned in the case of nickel, cobalt, bismuth, iron or potassium. Generally, the cocatalyst is present in the form of a moving bed and preferably it is regenerated and circulates, if appropriate, in the same way as the catalyst. 30 Preferably, in the cocatalyst of formula (II): - a' is comprised between 0.01 and 0.4, inclusive; - b' is comprised between 0.2 and 1.6, inclusive; - c' is comprised between 0.3 and 1.6, inclusive; - d' is comprised between 0,1 and 0-6, inclusive; R:/Brevels/20200/20293US-22/02/05 12 - e' is compri sed between 0.006 and 0.01, inclusive. - f' is comprised between 0 and 0.4, inclusive; - g' is comprised between 0 and 0.4, inclusive; - h' is comprised between 0.01 and 1.6, inclusive; 5 i' is comprised between 0 and 0.4, inclusive; - j' is comprised between 0 and 0.4, inclusive; - k' is compri sed between 0 and 0,4, inclusi ve; - l' is comprised between 0 and 0.4, inclusive; m' is comprised between 0 and 0.4, inclusive; and 10 n' is comprised between 0 and 0.4, inclusive. The weight ratio of the catalyst to the cocatalyst is generally greater than 0.5 and preferably at least 1. Advantageously, the cocatalyst is present in the two reactors. The catalyst and the cocatalyst are present in the form of solid catalytic 15 compositions. They can each be in the form of pellets, generally of 20 to 300 µm in diameter, the catalyst and cocatalyst pellets generally being mixed before implementation of the process according to the invention. The catalyst and the cocatalyst can also be present in the form of a solid catalytic 20 composition composed of pellets each of which comprises both the catalyst and the cocatalyst. EXAMPLES The following examples illustrate the present invention without limiting its scope. In the formulae given in Example 1, x is the quantity of oxygen bound to the 25 other elements and depends on their oxidation states. The conversions, selectivities and yields are defined as follows Number of moles of propane having reacted Conversion (%) of the propane= ----------------------------------------------------- x100 Number of moles of propane introduced Number of moles of acrylic acid formed Selectivity (% ) for acrylic acid = ------——-------------------------------—.,— x 100 Number of males of propane having reacted 35 R:/Brevels/20200/20293US-22/02/05 Number of moles of acrylic acid formed Yield (%) of acrylic acid = ------------------------------------------------ x 100 Number of moles of propane introduced 5 The selectivities and yields relating to the other compounds arc calculated in a similar way. The conversion ratio is the weight of catalyst (in kg) required to convert 1 kg of propane, Example1, (comparative) 10 A catalyst was prepared in the following way. 5.35 g of ammonium paramolybdate and 1.33 g of antimony trisulphate (Sb2SO4) are successively added under stirring to 30 ml of water heated to 80°C. Stirring is continued for 15 minutes. Separately, a solution containing 10 µmoles of vanadium is prepared by dissolving 2,63 g of hydrated vanadyl sulphate in 10 ml of distilled water 15 heated to 80 C. The second solution is added to the first and the mixture is stirred for 15 minutes before being introduced into a 70 ml autoclave covered with Teflon®. Then nitrogen is bubbled through for 5 minutes so that it substitutes the air present in the autoclave, before it is closed. The autoclave is then set at 175°C for 24 hours. After this period, the autoclave is cooled down with tap water for 10 minutes. The 20 black-purple solid obtained in the autoclave is separated from the solution by filtration, thoroughly washed with distilled water and dried for 12 hours at 80°C. The precursor thus obtained is then precalcinated under air at 280°C for 2 hours, then calcinated under nitrogen flow (25 ml/h/g) at 600°C for 2 hours. In this way catalyst 1 is obtained. This catalyst is tested. The results are shown in Tables 2 and 3. 25 Example 2 (comparative) A catalyst was prepared in the following way. 535 g of ammonium paramolybdate and 0.55 g of a 31 % solution of hydrogen peroxide and 0.74 g of antimony trioxide are successively added to 20 ml of water heated to 80°C under stirring. Stirring is continued for 60 minutes until the antimony 30 oxide is dissolved. Separately, a solution containing 12 µmoles of vanadium is prepared by dissolving 3.16 g of hydrated vanadyl sulphate in 10 ml of distilled water heated to 80'C. The second solution is added to the first and 1.89 g of oxalic acid in powder form is added to the solution. The mixture is stirred for 10 minutes before being introduced into a 70 ml autoclave covered with Teflon®. Then nitrogen is R:/Brevels/20200/20293US-22/02/05 bubbled through for 5 minutes so that it substitutes the air present in the autoclave, before the Utter is closed. The autoclave is then set at 175 QC for 48 hours. After this period, the autoclave is cooled down with tap water for 10 minutes. The black-purple solid obtained in the autoclave is separated from the solution by 5 filtration, thoroughly washed with distilled water and dried for 12 hours at 80°C The precursor thus obtained is then calcinated under nitrogen flow (25 ml/h/g) at 600°C for 2 hours. In this way catalyst 2 is obtained. This catalyst is tested. The results are shown in Tables 2 and 3, Example 3 10 A catalyst was prepared in the following way. 5.35 g of ammonium paramolybdate and 0,55 g of a 31 % solution of hydrogen peroxide and 0.74 g of antimony trioxide arc successively added to 20 ml of water heated to 80°C under stirring. Stirring is continued for 60 minutes until the antimony oxide is dissolved. Separately, a solution containing 9 µmoles of vanadium is 15 prepared by dissolving 237 g of hydrated vanadyl sulphate in 10 ml of distilled water heated to 80°C A third solution containing 3 µmoles of niobium is prepared simultaneously by dissolving under stirring, 1.94 g of hydrated niobium oxalate in 10 ml of distilled water heated to 80°C. The second solution is added to the first and stirred continuously for 5 minutes. Finally, the solution containing niobium is added. 20 The mixture is stirred for 10 minutes before being introduced into a 70 ml autoclave covered with Teflon®. Then nitrogen is bubbled through for 5 minutes so that it substitutes the air present in the autoclave, before the latter is closed. The autoclave is then set at 175°C for 48 hours. After this period, the autoclave is cooled down with tap water for 10 minutes. The 25 black-purple solid obtained in the autoclave is separated from the solution by filtration, thoroughly washed with distilled water and dried for 12 hours at 80°C. The precursor thus obtained is then calcinated under nitrogen flow (25 ml/h/g) at 600°C for 2 hours. In this way catalyst 3 is obtained. This catalyst is tested under the same conditions as the other catalysts. The results are shown in Tables 2 and 3, 30 Example 4 A catalyst was prepared in the following way. 5,35 g of ammonium paramo!ybdate and 0.55 g of a 31 % solution of hydrogen peroxide and 0.74 g of antimony trioxide are successively added to 20 ml of water heated to 80°C under stirring. Stirring is continued for 60 minutes until the antimony R:/Brevels/20200/20293US-22/02/05 oxide is dissolved. Separately, a solution containing 12 µmoles of vanadium is prepared by dissolving 316 g of hydrated vanadyl sulphate in 10 ml of distilled water heated to 80°C. A third solution containing 1.5 µmoles of niobium is simultaneously prepared by dissolving under stirring, 0.97 g of hydrated niobium oxalate in 10 ml of 5 distilled water heated to 80°C The second solution is added to the first and stirred continuously for 5 minutes. Finally, the solution containing niobium is added. The mixture is stirred for 10 minutes before being introduced into a 70 ml autoclave covered with Teflon®. Then nitrogen is bubbled through for 5 minutes so that it substitutes the air present m the autoclave, before the latter is closed. The autoclave is 10 then set at 175°C for 4S hours. After this period, the autoclave is cooled down with tap water for 10 minutes. The black-purple solid obtained in the autoclave is separated from the solution by filtration, thoroughly washed with distilled water and dried for 12 hours at 80°C. The precursor thus obtained is then calcinated under nitrogen flow (25 ml/h/g) at 600°C 15 for 2 hours. In this way catalyst 4 is obtained. This catalyst is tested under the same conditions as catalyst 3. The results are shown in Tables 2 and 3- Example 5 (comparative) A catalyst was prepared in the following way. 2.0008 g of hot (90°C) ammonium metavanadate is dissolved in 45 ml of water. Then 20 1.2149 g of antimony trioxide (senarmontite phase) and 10.0142 g of ammonium heptamolybdate are added. The mixture is taken to reflux under argon, the temperature is set at 70°C and the solution is left under stirring for 14 hours. The resulting mixture is opaque blue-black. 2 ml of 30 % hydrogen peroxide is added using a syringe and the solution is left under stirring. The colour progressively 25 changes to orange passing through khaki green tones. A light precipitate is then distinguished in a dark orange solution. In parallel, 1.7254 g of oxalic acid was dissolved in 20 ml of water and this solution is added to the first, which remained at 70ºC, without a change of colour or appearance being observed. The pH of the solution is then 3 to 4. The mixture is left to mature for another 30 minutes, then it is 30 dried in the oven for 12 hours at 110°C. The amorphous precursor is then precaicinated under air (15 ml/min/g) at 300°C, for 4 hours, then calcinated under nitrogen flow (15 ml/min/g) for 2 hours at 600CC. in this way catalyst 5 is obtained. This catalyst is tested under the same conditions as the other catalysts. The results are shown in Table 4. R:/Brevels/20200/20293US-22/02/05 Example 6 Catalyst 6 is prepared in the same way as catalyst 5, except that 0.75 g of niobic add is dissolved in the oxalic acid solution, by heating it at 70°C for 2 hours. This solution is centriruged before being mixed with the solution containing the other 5 elements. The results are shown in Table 4. Example 7 A catalyst was prepared in the following way. 5.35 g of ammonium paramolybdate is added under stirring to 20 m) of water heated to 80°C, Separately, a solution containing 15 µmoles of vanadium is prepared by 10 dissolving 3,94 g of hydrated vanadyl sulphate in 20 ml of distilled water heated to 80ºC The second solution is added to the first and the mixture is then stirred for 10 minutes before being introduced into a 70 ml autoclave covered with Teflon®. Then nitrogen is bubbled through for 5 minutes so that it substitutes the air present in the autoclave, before the latter is closed. The autoclave is then set at 175°C for 24 hours. 15 After this period, the autoclave is cooled down with tap water for 10 minutes. The black-blue solid obtained in the autoclave is separated from the solution by filtration, thoroughly washed with distilled water and dried for 12 hours at 80°C. The precursor thus obtained is then calcinated under nitrogen flow (25 ml/h/g) at 50O°C for 2 hours. In this way catalyst 7 is obtained. This catalyst is tested under the same 20 conditions as the other catalysts. Table 1: Summary table of the different preparations Example No. Composition of thesolution (without oxygen) Process of preparation Example 1Example 2Example 3Example 4ExamplesExample 6Example 7 Mo1.0V0.33Te0.17Mo1.0V0.40Sb17Mo1.0V0.30Sb17Nb0.10Mo1.0V0.40Sb17Nb0.05Mo1.0V0.30Sb0.17Mo1.0V0.30Sb0.17Nb0.05Mo1.0V0.50 Hydrothermal synthesisHydrothermal synthesisHydrothermal synthesisHydrothermal synthesisEvaporation dryingEvaporation dryingHydrothermal synthesis Table 2: Oxidation of propane at 320°C on antimony catalyst' Conversion (%) Selectivity (%) Yield (%) Ex.No. C3H3 Acrylicacid C3H6 Acetone Aceticacid CO CO2 Acrylic acid 12347 9.7413.110.221,611.1 34.312.144.140.05.41 19.619,326-915.019.5 5.882.053.452.000.97 17.023,510.316,020.4 14.021.17.8913.033,1 9.2521.97-3313.020.6 3.341.594.508.640.60 R:/Brevels/20200/20293US-22/02/05 17 Table 3: Oxidation of propane at 360°C on antimony catalysts Conversion (%) Selectivity (%) Yield (%) Ex.No. C3HS Acrylicacid Acetone Aceticacid CO CO2 Acrylicacid 12347 20.821.921.237.823.4 33,911.045.119.04,21 15.314.717.7 8.011.4 1.701.231.071.000.27 17.522.811.821.014.8 17.624.713.124.041.4 14.025.511.327.027.9 7.052,419.567.080.98 Table 4: Oxidation of propane on the evaporation-drying catalysts Reactiontemp. Conv.% Selectivity (%) Yield(%) Ex.No. °C Acrylicadd Acetone Aceticacid CO CO2 Acrylic acid 56 320320 9.767.21 27.124.0 30.235.7 5.202.91 13.013.4 13.4133 11.110.7 2.331.73 56 360360 15.623.8 29.425.1 19.818.7 1.770.59 15.211.9 17.823.9 16.019.9 5.065.96 In the case of examples I and 3, the effluents of the test are collected for 4 5 hours in an ice-trap. 2 analyses by chromatography coupled with a mass spectrometer are carried out per sample. 5 main products are detected per sample: acetone, water, acetic acid, propionic acid and acrylic acid. The molar ratios propionic acid/acrylic acid are thus calculated for each 10 sample, for reaction temperatures of 320°C and 360°C. The average of the two analyses carried out per sample is given in Table 5 below. Table 5: Molar ratio Propionic acid/Acrylic Acid Example 320c 'C 360°C 13 6.496.36 %% 1.64%1.42% It is noted that the molar ratio decreases with an increase in the temperature 15 and trie presence of niobium in the composition of the catalyst. Example 8 Preparation of a catalyst A of formula: Mo1V0.30sb0.15Nb0.10Si0.030x and its precursor. Synthesis of the precursor This synthesis allows the preparation of approximately 100 g of dry precursor. R:/Brevels/20200/20293US-22/02/05 ' Stage I: Dissolution-precipitation Solution A 12.3 g (0-1052 mol V) of ammonium metavanadate (AMV) are placed in solution in 260 ml of demineralised water, in a 1 litre glass SVL® reactor, under stirring, in an 5 oil bath thermostatically controlled at 128°C A yellow solution is obtained. 7.7 g (0.0528 mol Sb) of Sb2O3 are added to the limpid solution (small addition of water in order to rinse the funnel), then 61.8 g of ammonium heptamolybdate (AHM, 03501 moles of Mo) are added. After the addition of AHM, the reactor is flushed with nitrogen, the reaction is stirred continuously, at reflux, for 4 hours. Gradually a blue- 10 black solution is obtained. Solution B 6 g (0.0530 mol) of an aqueous solution of H2O2 at 30 wt-% is then added slowly (approximately 30 minutes). In order to obtain a limpid orange solution, two drops of pure oxygenated water are added. 15 Solution C Then 49.1 g of Ludox® AS40 silica (nSi = 0.327 mole) is added in one go, and the solution becomes slightly cloudy. The solution formed is called solution C Solution D A solution D is prepared at the same time as solution A. 100 g of distilled water, 5.9 g 20 of niobic acid marketed by the Brazilian company CBMM i.e. nnb = 0.035 mol, and 13.2 g of Prolabo oxalic acid i.e. noxaiatc = 0.105 mole is introduced into a 500 ml beaker. The mixture is heated at 60°C under stirring for 2 hours, then taken to 30ºC The solution is then centrifuged at 6200 r.p.in. for 12 minutes in order to obtain a limpid solution. 25 Solution D is added to solution C in one go- A fluid gel is obtained which is orange then yellow. Stining is continued for 30 minutes under nitiogen flow, under reflux. Staee 2: Drying The gel is then dried in a ventilated oven overnight, on plates covered with Teflon®, at 130ºC. 863 g of dry precursor are recovered. The precursor is in the form of sheets, 30 black on the top and a thin green film underneath- In this way a precursor is obtained. Staze 3: Beat treatment 30 g of precursor obtained previously are precalcinated at 305°C with an air flow rate of 18.7 ml/min/g. R:/Brevels/20200/20293US-22/02/05 After calcination, at 601°C under a nitrogen flow rate of 49.8 ml/min/g, a weight of calcinated solid of 24.6 g is obtained. This catalyst is called CATALYST A, Example 9 Preparation of a catalyst B with the formula: Mo1 V0.30Sb0.15Nb0.10Si0.70Oxand its precursor, 5 Synthesis of the precursor The process is carried out as in Example 8, but with; - 3075 g (0.2630 mole of V} of ammonium metavanadate (MVA); -19.25 g (0.1321 mole of Sb) of Sb2O3; -154.5 g (0.8753 mole of Mo) of ammonium heptatnolybdate (AHM); 10 -15.25 g (0 .1 46 mol) of an aqueous sol ution o fH2O2 at 3 0 wt -%; - 100 g of Ludox® AS40 silica (nsi, = 0.6667 mole); - 14.75 g of CBMM niobic acid i.e. nNb = 0.088 mole; and - 33-0 g of Prolabo® oxalic acid i.e. noxalate = 0262 mol. 259 g of dry precursor are recovered. The precursor is in the form of black sheets on 15 the top and thin yellow-green films underneath. 25 g of this precursor are precalcinated at 321°C under static air for 4 hours, then calcinated at 598°C at a flow rate of nitrogen of 51.85 ml/min/g for 2 hours. A weight of 20.30 g of calcinated solid is obtained. This catalyst is called catalyst B, Example 10 20 Preparation of a catalyst C with the formula: Mo1 V0.30Sb0.15Nb0.10Si0.93Ox, and its precursor. Synthesis of the precursor A 10 litre reactor with a double jacket is used. The diagram of the installation is given in Figure 2. The installation comprises the reactor with a double jacket 1, equipped with a draw off 2 and an oil bath 3 thermostatically controlled at 140°C (so that the 25 temperature inside the reactor is approximately 99°C), a stirrer 4 designed to operate at 125 r.p.in,, an inlet 5 for the reagents, an inlet 6 for the nitrogen, a cooler 7 connected to a vent 8. 2600 % of water, 123 g of ammonium metavanadate (1.052 mole), 77 g of antimony oxide (0.528 mol), and 618 g of ammonium heptamolybdate (3.501 mole) is 30 introduced cold under stirring and under nitrogen flow. After the start of heating, the mixture quickly changes to green, then to blue-black. After stabilisation of the internal temperature of the reactor (T = 99°C), 4 hours of stirring of the solution allow it to be perfectly homogeneous. 60 g of oxygenated R:/Brevels/20200/20293US-22/02/05 20 water dilated in 500 g of water are added so as to obtain a limpid orange solution (oxidation of all the cations present). 30 minutes laterT 491 g (3.27 mole) of colloidal silica is introduced as well as a solution of niobic acid (59 g, 0.5 mol) and oxalic acid (132 g, 1.05 mol) previously 5 heated for two hours and centriiuged (12 minutes at 6200 r.p .in.). Another 30 minutes later, the heating is stopped but stirring is continued overnight in order to retain a homogeneous solution. The mixture has taken on a yellow colouring and the consistence of a gel. Forming 10 A laboratory atomizer (ATSELAB® by Sodeva) is used. The atomization takes place in an air atmosphere. The working parameters are globally: - flow rate of nitrogen of the order of 40 m3/h; - flow rate of slurry of the order of 2600 g/h; 15 - inlet temperature of the gas; 290°C; - outlet temperature of the gas: 134°C. The increase in the rate of dry material in the slurry is carried out in a rotary evaporator to 30.8 wt.-%. A fraction comprised between 40 and 160 µm is recovered in the chamber which 20 corresponds to the precursor. Heat treatment 26.6 g of the fraction obtained previously, i.e. the precursor, are precalcinated foe 4 hours at 316QC under static air in order to produce a precalcinated solid. The precalcinated solid is then calcinated for 2 hours at 598° C under a flow rate of 2 5 nitrogen o f 49.83 mVg/min and thus produces 21 g of catalyst called CATALYST C. Example tl Catalyst tests a) Apparatus In order to simulate the process according to the invention, simulations were 30 carried out in the laboratory in a laboratory fixed bed reactor, by generating propane pulses and oxygen pulses. The following are loaded from the bottom to the top of a vertical reactor with cylindrical shape and made of pyrex; R:/Brevels/20200/20293US-22/02/05 21 - a first height of 2 ml of silicon carbide in the form of particles of 0,125 mm in diameter, - a second height of 5.00 g of catalyst in the form of particles of 0.02 to 1 mm diluted with 10 ml of silicon carbide in the form of particles of 0.125 mm in 5 diameter, - a third height of 2 ml of silicon carbide in the form of particles of 0.125 mm in diameter, and - a fourth height of silicon carbide in the form of particles of 1.19 mm in diameter, so as to fill all of the reactor. 10 b\ Tests of catalyst A I) Operating process The reactor is heated to 250°C and the vaporizer to 20G'C- The electric initiation of the water pump is initiated. Once the reactor and the vaporizer have reached the temperatures given above, 15 the water pump is actuated and the reactor temperature is raised to 400ºC and it is left for 30 minutes so that the hot point is stabilized. Then, oxygen is introduced in 10 pulses of 23 seconds each in order to sufficiently oxidize the catalyst. The catalyst is considered to be totally oxidized when the temperature of the hot spot has stabilized, i.e, when there is no more 20 exothermal activity due to the reaction (by monitoring the catalyst temperature measured using a thermocouple placed in the catalyst bed, the fluctuations in temperature can be seen as a function of the pulses). Then the measurements relating to the production of acrylic acid itself can be carried out. 25 For each balance, liquid samples are taken. Gas samples are also taken using gas bags, each sample representing a certain number of cycles. - Each small gas-washing bottle (with a 25 ml capacity and filled with 20 ml of water) is equipped with a gas bag, and when the bottle is connected to the outlet of the reactor (as soon as the liquid bubbles), the bag is open and the chronometer is started. 30 In order to verify the oxidation state of the catalyst, another series of ten 23- second puises of oxygen is carried out. It shows that the oxidation state of the solid has been maintained during the balancing. The liquid effluents are analyzed on a HP 6890 chromatograph, after having carried out a specific calibration. R:/Brevels/20200/20293US-22/02/05 22 The gases are analyzed during the balancing on a Chrompack micro-GC chromatograph. An assay of the acidity is carried out on each bottle, in order to determine the exact number of moles of acid produced during each microbalancing and to validate 5 the chromatographic analyses, i) Test TA1 This is a test of the oxidation of propane carried out in the absence of molecular oxygen. This test was carried out with partial pressures of propane and oxygen corresponding to the following ratios: 10 For the ox idation: propane/He-Kr/H2O: 10/45/45 For the regeneration: O/He-Kr/H3O: 20/45/45, with a flow rate of He-Kr of 4.262 Nl/h (Nl/h = normal litres per hour), i.e. litres/h at 0 C and at atmospheric pressure) and at a temperature of 400 C. In this test, aredox balance is composed of 60 cycles. A redox cycle represents'. 15 -12.2 seconds of propane in a continuous flow of helium-krypton/water, - 45 seconds of continuous flow of helium-krypton/water, - 20 seconds of oxygen in a continuous flow of helium-fcrypton/water, - 45 seconds of continuous flow of helium-krypton/water. For each balance, 4 liquid samples are carried out, each representing 15 cycles and 4 20 gas samples using gas bags, each sample representing 15 cycles. ii) Test TA2 This is also a test of the oxidation of propane carried out in the absence of molecular oxygen. In this test, the duration of the propane pulse (as well as that of the oxygen) is 25 modified during the balance thus allowing observation of the behavior of the catalyst when in a more or less rich redox mixture. The duration of the oxygen pulse is still twice as great as that of propane, and with a double flow rate, in order to keep the catalyst oxidized. The partial pressures of propane and oxygen remain the same as in the preceding 30 test TA1: For the oxidation: propane/He-Kr/H2O: 10/45/45 For the regeneration: O2/He-Kr/H2O; 20/45/45, with a flow rate of He-Kr of 4.262 Nl/h at a temperature of 400 C. R:/Brevels/20200/20293US-22/02/05 23 In this example of 60 cycles the balance is divided into six microbalances in the following way; 2 first microbalances of 7 and 8 cycles: 10 seconds of propane in a flow of He-Kr/H2O, 5 45 seconds under He-Kr, 20 seconds of O2 in a flow of He-Kr, 45 seconds under He-Kr. 3rd microbalance of 15 cycles: 5 seconds of propane in a flow of He-Kr/H2O, 10 50 seconds under He-Kr, 10 seconds of O^ in a flow of He-Kr, 55 seconds under He-Kr. 4® microbalance of 8 cycles: 2 seconds of propane in a flow of He-Kr/H2O, 15 50 seconds under He-Ki, 4 seconds of O3 in a flow of He-Kr, 55 seconds under He-Kr. 5th microbalance of 8 cycles: 20 seconds of propane in a flow of He-Kr/H2O, 20 45 seconds under He-Kr, 40 seconds of O2 in a flow of He-Kr, 45 seconds under He-Kr. 6th microbalance of 7 cycles: 30 seconds of propane in a flow of He-Kr/H2O, 25 45 seconds tinder He-Kr, 60 seconds of O2 in a flow of He-Kr, 45 seconds under He-Kr. The durations of the pulses which have just been given are theoretical iii)Test TA3 30 In this test the oxidation of propane is carried out in the presence of molecular oxygen, at 400 C. The duration of the injection of oxygen in the propane pulse is varied by preserving the constant pressures of propane and of oxygen. The balance of 40 cycles in this case is broken down as follows: R:/Brevels/20200/20293US-22/02/05 10 cycles of 30 s of propane + 5 s of O2 (the oxygen being injected at the start of the injection of propane), with the proportions propane/O2/He-Kr/H2O of 30/30/45/45, with a flow of helium-krypton of 4.262 Nl/h. Then there is an intermediate pulse composed only of the flow of carrier gas He- 5 KI/H2O of 60 s, then an oxygen pulse with the proportions O2/He-Kr/H2O of 20/45/45, for 60 s and another intermediate pulse of He-Kr/H2O of 60 s. Then there in another series of 10 cycles of 30 s of propane + 10 s of oxygen, with the proportions propane/O2/He-Kr/H2Oof 30/30/45/45, with a flow of helium- krypton of 4.262 Nl/h. Then there is an intermediate pulse composed only of the flow 10 of carrier gas He-Kr/H2O of 60s, then an oxygen pulse with the proportions o2/He- Kr/H2O =20/45/45, for 60 s and another intermediate pulse of He-Kr/H2O of 60 s. Then, there is another series of 10 cycles of 30 s of propane + 15 s of O2, with the proportions propane/O2/He-Kr/H2O of 30/30/45/45, with a flow of helium- kiypton of 4.262 Nl/h. Then there is an intermediate pulse composed only of the flow 15 of carrier gas He-Kr/H2O of 60 s, then an oxygen pulse with the proportions O2He- Kr/H2O = 20/45/45, for 60 s and another intermediate pulse of He-Kr/H2O of 60 s. Then, there is another series of 10 cycles of 30 s of propane + 20 s of O2, with the proportions propane/O2/He-Kr/H2O of 30/30/45/45, with a flow of helium- krypton of 4.262 Nl/h. Then there is an intermediate pulse composed only of the flow 20 of carrier gas He-Kr/H2O of 60 s, then an oxygen pulse with the proportions 02/He- Kr/H2O of 20/45/45, for 60 s and another intermediate pulse of He-Kr/H2O of 60 s. As in the test TA2, the durations of the pulses which have just been given are theoretical. 2) Results 25 The results of the tests TA1, TA2 and TA3 are shown in the tables below. In these tables, the theoretical durations of the pulses are no longer shown as they were previously, but the corresponding real durations which were calculated . using a specific calibration. R:/Brevels/20200/20293US-22/02/05 25 Table 6-Test TA1 TA2 TA3 Conditions in the reactionpropane/He-Kr/H2O or propane+O2/He-Kr/H2O 10/45/45 10/45/45 30+30/45/45 Conditions in regeneration O2/He-Kr/H2O 20/45/45 20/45/45 20/45/45 Comments Standardtest Variation in the duration of theinjection of propane during the balance Variation in the duration of theinjection of d in the propanepulse. O2 injection at the startof the propane injection Summary Average Flask4 Flask3 Flask2 Flask5 Flask6 Flask1 Flask2 Flask3 Flask4 Number of CYCLES 60 15 15 3 8 7 10 10 10 10 Duration of the propane pulse 12,2 4.4 7.6 12.9 22.5 32-8 35 33.6 33.7 32.7 Duration of the oxygen pulse injected into thepropane - ■"- - - - - 5 10 15 20 Yields (%) Acetaldehyde 0.00 0,00 0.00 0-00 0.00 0.00 0.00 0.00 0,00 0.00 Propyladehyde 0.00 0.00 0.00 0.00 0.00 0,00 0.00 0.00 0.00 0.00 Acetone 0.17 0.17 0.16 0.16 0-16 0. 18 0.15 0.15 0.15 0.15 Acrolein 0.02 0.03 0.02 0.03 0,02 0.02 0.01 0.01 0001 0.02 Allyl alcohol 0.02 0.03 0.02 0.00 0.00 0.00 0.00 0,00 0.00 0.00 Allyl acrylate 0.00 0.00 0.00 0.00 0,00 0.00 0.00 0.00 0.00 0.00 Acetic acid 1.40 1.97 1.47 1.46 1.06 1.09 0.63 0.74 0.75 0.82 Propionic acid 0,11 0-15 0.12 0.13 0.08 0.09 0.05 0-06 0.06 0.07 Acrylic add 11.43 15.80 11-79 10.25 7.88 7.50 3.(SB 5.21 5.77 6.59 Carbon monoxide 1.66 2.26 1.80 1.68 1.24 1,07 0.64 0.70 0.80 0.90 Carbon dioxide 0.81 1.23 0-87 0.91 0.75 0-60 0.83 0.44 0.50 0.56 Propylene 3.56 3.56 3,70 3.05 3.57 3.44 3.34 3.57 3.16 3.37 Propane 79.60 75.02 80 .04 82.1I 85.21 35,74 90.58 89-26 87-76 87.01 Carbon balance (%) 98.8 100.2 100.0 100.4 100.0 99.7 59.9 100.1 | 99.6 100.0 R:/Brevels/20200/20293US-22/02/05 26 Table7-Test TA1 TA2 TA3 Conditions in the reactionpropan/He-Kr/H2O or propane-O2/He-Kr/H2O 10/45/45 10/45/45 30+30/45/45 Conditions in regenerationO2/He-Kr/H2O 20/45/45 20/45/45 20/45/45 Comments Standardtest Variation in the duration of the propane pulse during thebalance Variation in the duration of the injection ofO2in the propane pulse Summary Average Flask 4 Flask 8 Flask 2 Flask 5 Flask 6 Flask 1 Flask 2 Flask 3 Flask 4 Number of CYCLES 60 15 15 % % 7 10 10 10 10 Duration of the propane injection 12.2 4.4 7.6 12.9 22-5 328 33 33.6 33.7 32,7 Duration of the oxygen pulses injected into thepropane 5 10 15 20 Selectivities(%) Acctaldehyde 0.00 0.00 0.00 0.00 0.00 0.00 0.04 0.03 0.00 0,03 Propanaldehyde 0,00 0.00 0.00 0.00 0,00 0.00 0.00 0.00 0.00 0.00 Acetone 0.91 0.66 0.78 0.89 1,05 1.28 1.58 1.39 1.26 1.14 Acrolein 0.12 0.13 0.12 0.15 0.13 0,14 0.14 0.12 0.12 0.12 Allyl alcohol 0.10 0.13 0.08 0.00 0.00 0-00 0,04 0,03 0,03 0.03 Allyl acrylate 0.00 0.00 0,00 0.00 0.00 0-00 0-00 0-00 0.00 0.00 Acetic acid 7.31 7.81 7.38 8.00 7.17 7.82 6-71 6-77 6.33 6.30 Propionic acid 0.56 0.58 0.58 0.70 0,53 0.64 0.58 0.56 0 53 0.51 Acrylic acid 59.56 62.69 39.14 56.10 53.45 53.60 39.37 47.83 50,82 Carbon monoxide 8,64 8,98 9.01 9.22 3.41 7.64 6.88 6.39 6,78 6.93 Carbon dioxide 4.23 4.88 4.35 4.97 5.07 4.32 8.88 4.04 4,24 4.33 Propylene 18.56 14.13 18.56 19.96 24.19 24.57 35.78 32. S3 31.83 29.80 Quantity of O2 consumed (g 0/k|g catalyst) 0.32 0.158 0.207 0.321 0.436 0.589 116 1.30 143 1,56 µmole of pnopane for 1 cycle 131.8 47.5 339.4 243.1 354.4 1072 1091 1094 1062 _µmole of Oi added per cycle ■ - - - 158 317 475 634 µmole of O3 consumed (products fonnedVcycle - - - - - 363 405 449 438 Propane conversion ratio(kg/catalyst/kg converted propane) 4233 9584 6942 4565 3166 2253 1107 971 852 803 R:/Brevels/20200/20293US-22/02/05 27 In test TA3, where the operation takes place in the presence of molecular oxygen, it is noted that the yields of acid acrylic increase much more quickly, as a function of the addition of oxygen in the propane pulse, than the yields in COx and acetic acid. A substantial gain in acrylic acid selectivity results. A lowering of the 5 selectivity of hydration products is also observed (acetone, propionic acid). The addition of oxygen also leads to a gain in conversion ratio which thus changes from 1107 to 803 kg/kg. c) Tests of catalyst B 1) Operating process 10 The apparatus used is the one described in Example 11a). i) Tests TB t and TB2 Catalyst B is tested under the same conditions and in the same way as for test TA1. ii) Test TB3 15 Catalyst B is tested under the same conditions and in the same way as for test TA3 (presence of molecular oxygen). iii) Tests TB4 to TB6 In the case of test TB4, catalyst B is tested under the same conditions and in the same way as for test TA2, at 420 C. 20 In the case of tests TBS and TB6, there is simply modification of the content of propane during the oxidation and of oxygen during the regeneration. iv) Tests TB7 in this test, the oxidation of propane is carried out in the presence of molecular oxygen, at 420 C. 25 The duration of the injection of oxygen in the propane pulse is varied by keeping the pressures of propane and of oxygen constant. The oxygen is injected at the end of the propane pulse to see if there is an influence on the catalytic performances compared to an injection at the start of the pulse. 30 The balance of 40 cycles is broken down as follows: 10 cycles of 30 s of propane + 20 s of O2 (the oxygen being injected at the end of the propane pulse), with the proportions propane/O2/He-Kr/H2O of 30/30/45/45, with a flow of helium-krypton of 4.27 Nl/h. R:/Brevels/20200/20293US-22/02/05 Then there is an intermediate pulse composed only of the flow of carrier gas He- Kr/H2O of 60 s, then a pulse of O2 with the proportions O2/He-Kr/H2O = 20/45/45, for 60 s and another pulse of carrier gas of 60 s. Then, there is another series of 10 cycles of 30 s of propane + 15 s of oxygen, 5 with the proportions propane/Oj/He-Kr/H^0 of 30/30/45/45, with a flow of helium- krypton of 4.27 Nl/h. Then there is an intermediate pulse composed only of the flow of carrier gas He-Kr/H2O of 60 s, then an oxygen pulse with the proportions O2/He- Kr/H2O = 20/45/45, for 60 s and another intermediate pulse of carrier gas of 60 s. Then, there is another series of 10 cycles of 30 s of propane + 10 s of O2, with the 10 proportions propane/O2/He-Kr/H2Oof 30/30/45/45, with a flow of helium-krypton of 4.27 Nl/h. Then there is an intermediate pulse composed only of the flow of carrier gas He-Kr/H2O of 60 s, then a pulse of O2 with the proportions O2/He-Kr/H2O = 20/45/45, for 60 s and another intermediate pulse of carrier gas of 60 s. Then, there is another series of 10 cycles of 30 s of propane + 5 s of O2, with the 15 proportions propaneO2/He-Kr/H2O of 30/30/45/45, with a flow of helium-krypton of 4,27 Nl/h. Then there is an intermediate pulse composed only of the flow of carrier gas He-Kr/H2O of 60 s, then a pulse of O2 with the proportions O2/He-Kr/H2O= 20/45/45, for 60 s and another intermediate pulse of carrier gas of 60 s, V) Tests TB8 20 In this test, there is also oxidation of the propane in the presence of molecular oxygen. There is comparison of the effect of the injection of oxygen at the end and at the start of the propane pulse by keeping constant pressures of propane and of oxygen but also a constant duration of injection of oxygen in the propane pulse. 25 The balance of 40 cycles is broken down as follows: 10 cycles of 30 s of propane + 20 s of O2 (the oxygen being injected at the end of the propane pulse), with the proportions propane/O2/He-Kr/H2O of 30/30/45/45, with a flow of helium-krypton of 4.27 Nl/h. Then there is an intermediate pulse composed only of the flow of carrier gas He-Kr/H2O of 60 s, then an intermediate pulse of O2 30 with the proportions O2/He-Kr/H2O = 20/45/45, for 60 s and another intermediate pulse of carrier gas of 60 s. Then, there is another series of 10 cycles of 30 s of propane + 20 s of oxygen (O2 being injected at the end of the propane pulse), with the proportions propane/O2/He- Kr/H2O of 30/30/45/45, with a flow of helium-krypton of 4.27 Nl/h. Then there is an R:/Brevels/20200/20293US-22/02/05 29 intermediate pulse composed only of the flow of carrier gas He-Kr/H2O of 60 sf then an intermediate pulse of oxygen with the proportions O2/He-Kr/H2O =20/45/45, for 60 s and another intermediate pulse of carrier gas of 60 s. 10 cycles of 30 s of propane + 20 s of 0; (the oxygen being injected at the start of 5 the propane pulse), with the proportions propane/O2/He-Kr/H2O of 30/30/45/45, with a flow of helium-krypton of 4.27 Nl/h. Then, there is an intermediate pulse composed only of the flow of carrier gas He-Kr/H2O of 60 s, then, an intermediate pulse of O2 with the proportions O2/He-Kr/H2O = 20/45/45, for 60 s and another intermediate pulse of carrier gas of 60 s. 10 Then, there is another series of 10 cycles of 30 s of propane + 20 s of O2 (the oxygen being injected at the start of the propane pulse), with the proportions propane/O2/He-Kr/H2O of 30/30/45/45, with a flow of helium-krypton of 4.27 Nl/h. Then, there is an intermediate pulse composed only of the flow of carrier gas He- Kr/H2O of 60 s, then an intermediate pulse of O2 with the proportions O2/He-Kr/H2O 15 =20/45/45, for 60 s and another intermediate pulse of carrier gas of 60 s. 2) Results of the tests a) Tests TB1 and TB2 Table 8-Test TB1 TB2 Conditions in the reaction propane/He-Kr/H2O 10/45/45 10/45/45 Conditions in regeneration O2/He-Kr/H2O 2Q/45M5 20/45/45 Temperature ( C) 400 420 Summary Average Average Number of CYCLES 60 60 Duration of the injection of propane 12.06 12.06 Yields (%) Acetaldehyde 0.00 0,00 Propanaldehyde 0.00 0.00 Acetone 0,22 0.17 Acrolein 0.00 0,01 Allyl alcohol 0.00 0.00 Allyl acrylate 0,00 0.00 Acetic acid 2.04 2.72 Propionic acid 0.08 0.04 Acrylic acid 13.0 15.3 Carbon monoxide 2.48 4.47 Conditions in the reaction. propane/He-Kr/H2O 10/45/45 10/45/45 Conditions in regeneration O2/He-Kr/H2O 20/45/45 20/45/45 Temperature ( C) 400 420 Summary Average Average Number of CYCLES 60 60 Duration of the injection of propane 12,06 12.06 Carbon dioxide 1.44 2.92 Propylenc . 3.42 3,69 Propane 74.7 71.2 R:/Brevels/20200/20293US-22/02/05 Carbon balance (%) 97,4 100.5 Selectivity (%) Acetaldebyde 0.00 0,00 Propanaldehyde 0.00 000 Acetone 0.99 0.59 Acrolein 0.00 0,03 Allyll alcohol 0.00 0.00 Allyl acrylate 0.00 000 Acetic acid 5.99 9.25 Propianic acid 0.33 0.15 Acrylic acid 57.4 522 Carbon monooxide 10.9 \52 Carbon dioxide 6.3 10.0 Propylene 15.1 126 Quantity of O2 consumed (g 0/kg catalyst) 0.42 0.59 µmole of propane for 1 cycle 135.9 135.9 Propane conversion ratio(kg catalyst/kg converted propane) 3309 2904 A better conversion is observed at 420 C than at 400 C. The acrylic acid selectivity changes from 57.4% to 52.2% when the temperature is modified. A clear decrease (division by two) of the selectivityes of acetone and propionic acid is 5 observed. The fact of increasing the temperature allows the conversion to be increased and the formation of hydration products as well as the conversion ratio to be decreased. The conversion ratio changes from 3300 to 2900 kg/kg by changing from 400 to 420 C 10 b) Tests TB4 to TB6 The results appear in the two tables below. It is observed that the increase in the partiai pressure of propane and/or of the duration of the injection of propane leads to a decrease in the yield of acrylic acid, but to the same yield of hydration products. The selectivities of hydration products therefore 15 increase with the reduction of the catalyst. The selectivities of acrolein and propylene also increase with the reduction of the catalyst. The reduced catalyst becomes less active. R:/Brevels/20200/20293US-22/02/05 20 31 Table 9 -Test TB4 TBS TB6 Conditions in the reaction propane/He-Kr/H2O 10/45/45 20/45/45 __, 30/45/45 Conditions in regeneration O2/He-Kr/H2O 20/45/45 20/45/45 30W5/45 Summary Flask4 Flask3 Flask2 FJask5 Flask6 Flask4 Flask3 Flask2 ■ Flask5 Flask6 Flask4 Flask3 Flask2 Flask5 Flask6 Number of CYCLES ]5 15 8 8 7 15 15 8 8 15 15 8 8 7 Duration of the injection of propane 4.5 7.4 12.35 21.4 30.6 4.4 7.5 12,6 22.7 31.8 4.35 6.85 12.3 21.8 29.09 Yields (%) Acetaldehyde 0.00 0.00 0.00 0.00 0-00 0.00 0.00 0,00 0.00 0.00 0.00 0.00 0.00 0.01 0.0J Propanaldehyde 0-00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0,00 0.00 Acetone 015 0.16 0.20 0.22 0,24 0.20 0.21 0.23 0.25 0-25 0.21 0.20 0.24 0.24 0.23 Acrolein 0.00 0.00 0.00 0.00 0.02 0.00 0.02 0.02 0.02 0.02 0.02 0.02 0.03 0.02 0.02 Allyl alcohol 0.00 0.00 0.00 0.00 0.00" 0.00 0.00 0.00 0.00 0,00 0.00 0.00 0,00 0.00 0.00 Allyl acrylate 0.00 0,00 0,00 0.00 0,00 0.00 0.00 0,00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Acetic acid 3.56 2.(7 2.71 2.53 2.28 2.84 2.62 2.30 1.74 1.56 2.67 2.0O 1.89 1.37 1.21 Prcpionic acid 005 0.05 0.05 0.04 004 0.05 0.05 0,04 0.04 0.04 0.05 0.04 0.04 0.04 0.03 Acrylic acid 24.00 15.96 11.34 9.81 15.61 13.39 10.03 6.84 5,80 13.60 8.88 8.00 5,28 4.44 Carbon monoxide 5.75 4.73 3.97 3-20 2,74 3.S6 3.28 2.56 1.67 ]-46 3.32 2,5 8 1.38 1,21 1.07 Carbon dioxide 3.40 2.48 2.51 2.J5 2-00 2.3$ 2,16 2.05 1,40 1.29 2.34 2.07 1.59 1.10 0.96 Propylene 126 3.57 3.62 3-7 1 3.67 3.S2 3.76 3.81 3.77 1.55 3.88 3.85 3.84 3.65 3.42 Propane 60,36 67.20 70,96 76.34 79.25 71.46 74.03 79.25 84.20 85.95 74.10 80,27 82.75 87.11 88.50 Carbon balance (%) 100.5 99.9 100.0 100.0 100.0 100.2 99.5 100.3 90-9 99.9 100.2 99.9 100.3 100.0 99,9 R:/Brevels/20200/20293US-22/02/05 Table10- Test TB4 TB8 Conditions in the reactionPropane/He-Kr/H2O 20/45/45 30/45/45 Conditions in regenerationO2/He-Kr/H2O 20/45/45 20/45/45 30/45/45 Summary Flask4 Flask Flask2 Flask5 Flask6 Flask4 Flask3 Flask2 Flask5 Flask6 Flask4 Flask3 Flask2 Flask5 Flask6 Number of cycles 15 15 6 8 7 15 15 8 8 6 15 15 8 8 7 Duration of the injection of propane 4.5 7.4 12.35 21.4 30.6 4.4 7.5 12.6 22.7 31.8 4,35 6-85 12.3 21.8 29.9 Yields (%) Acetaldehyde 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.05 0.06 Propanaldehyde 0.00 0.00 0.00 0-00 0-00 0.00 0.00 0.00 0.00 0.00 0,00 0.00 0^00 0.00 0.00 Acetone 0.37 0.48 0.68 0.94 1.13 0.70 0.83 1.11 1.58 1.80 0.79 1.02 1.37 1.87 2.00 Acrotein 0.00 0.00 0-00 0-00 0.11 0.00 0.08 0.12 0.14 0.16 0.08 0,10 ,0.14 0.18 017 Allyl alcohol 0.00 0.00 0.00 0.0~0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Allyl acrylate 0.00 0.00 0.00 0.00 0.00 0.00 0,00 0.00 0.00 0.00 0.00 0,00 0.00 0.00 000 Acetic acid 8.56 8.17 9.34 10.66 10.97 9.89 10.27 10 91 11.04 11.19 10.22 10.18 10.51 10.59 10.66 Propionice acid 0.11 0.15 0.18 0.19 0.21 0.19 0.20 0.21 0.26 0,26 0.20 0.21 0,24 0.29 0.28 Acrylic acid 59.77 58.26 54,99 49.96 47.15 ,54.27 52,54 47.64 43.5I 41.51 52.14 45,22 45.69 40.89 36,95 Carbon monoxide 14.31 14.45 13.89 13-52 13,16 13,41 12.86 12,17 10.62 10.48 12-72 13.12 10.72 9-36 9.40 Carbon dioxide 5.47 7.58 8.66 9.08 9.60 8.26 8.46 , 9.74 8.88 9.20 8.97 10.55 9.09 8.53 8,46 Propylene |_8.11 10 .91 12-47 15,.66 17.67 13.29 14.76 18.11 23.97 125.39 14.87 19.60 2194 28.24 29.99 Quantity of oxygen consumed(gO/kg catalysts) 0.305 0.397 0,586 0.8.15 1.012 0.387 0,575 0.793 0.998 1.232 0.525 0.617 0.934 1.14! 1,360 µmole of propane/1 cycle 50.7 83.4 139.2 241.2 344.9 94.0 160.2 269.1 484,7 679.1 141.3 222.5 399.5" 708.0 971.1 propane conversion ratioKg catalyst/Kg converted propane 5659 4159 2815 1994 1590 4243 2736 2038 1486 1193 3110 2593 1652 7247 1019 32 R:/Brevels/20200/20293US-22/02/05 33 C) Tests TB3.TB7 and TB8 The results appear in the three tables below. It is observed that the addition of molecular oxygen allows a clear decrease in the conversion ratio while maintaining a good selectivity. There is a change from 5 2904 kg of catalyst/kg of converted propane for a standard test to 1019 kg of catalyst/kg of converted propane for a test with variation of pulse duration (30 s of propane with propane or oxygen/He-Kr/H2O: 30 or 30/45/45). With the addition of oxygen it is from 460 to 500 kg of catalyst/kg of converted propane- It is advantageous to add oxygen which allows not only a further decrease of the 10 conversion ratio, but also an increase in the acrylic acid selectivities. It is observed that the catalyst, even reduced, can remain dehydrogenating. R:/Brevels/20200/20293US-22/02/05 34 Table-Test TB3 TB7 TBS Conditions in the reactionpropane-O2/He-Kr/H2O 30+30/45/45 30+30/45/45 Conditions in regenerationO2/He-Kr/H2O 20/45/45 20/45/45 20/45/45 Comments Variation in the duration of theinjection of O2 in the propanepulse Variation in the duration of theinjection of O2 in the propanepulse. Injection of O2 at the endof the pulse Duration of O2 injection into theconstant propane pulse. Injectionof O2 at the end of the pulse thenat the start of the pulse Summary Flask1 Flask2 Flask3 Flask4 Flask1 Flask2 Flask3 Flask4 Flask1 Flask2 Flask3 Flask4 Number of CYCLES 10 10 10 10 10 10 10 10 10 10 10 10 Duration of the injection of propane 33-3 34.4 34.2 34.6 34.4 36.5 34.2 33.6 34.4 34.3 34.6 35 Duration of the oxygen pulse injected into thepropane pilse 5 10 15 20 20 15 10 5 20 20 20 20 Yields (%) Acetaldehyde 0.01 001 0.01 0-00 0.01 001 0.01 0.00 0.00 0.00 0.00 Propanaldehyde 0.00 0-00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 000 0.00 Acetone 0.20 0.20 0.19 0.16 0.06 0.08 0.05 0-15 0.15 0.17 0.17 Acrolein 0.02 0.02 0.02 0.02 0.02 0-02 0.01 0-02 0.02 0.02 0.02 Allyl alcohol 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Allyl acrylate 0.00 0.00 0.00 0.00 0.00 0.00 0.00 000 0.00 0.00 0.00 Acetic acid US 1.55 1.68 1.76 1.76 1-51 1.42 1-77 1.69 1.89 1.87 Propionic acid 0.03 0.04 0.04 0.04 0.04 0.04 0.03 0.04 0.04 0.04 0.04 Acrylic acid 6.86 8.30 9.86 11.04 10.33 6.98 5.57 10.64 10.21 11.54 11.40 Carbon monoxide 1.61 1.73 2.02 2-34 2.42 1.79 1.50 2.69 2.54 2.53 2.47 Carbon dioxide 1.37 1.41 1.52 1.77 1.95 1.59 1.36 2.08 1.98 2.02 2.00 Propylene 3.70 3.99 4.17 4.27 4.09 3.70 3.49 4.06 4.08 4.20 4.22 Propane 84.96 82.92 80.65 78.78 79.61 84.51 86.81 78.74 79.35 77.79 77.7S Carbon balance (%) 100.2 100.2 100-1 100.2 100.3 IO0.2 100.2 100.2 100.1 10O.2 100.0 AN analysis problem was detected on Flask 2. for this reason the results obtained are not shown. R:/Brevels/20200/20293US-22/02/05 35 Table 11 - Test TB3 TB7 TB8 Conditions in the reactionpropane-O2/He-Kr/H2O 30+30/45/45 30+30/45/45 30+30/45/45 Conditions in regenerationO2/He-Kr/H2O 20/45/45 20/45/45 20/45/45 Comments Variation in the duration of theinjection of O2 in fhe propane ■pulse Variation in the duration of theinjection of O2 in the propane pulse.Injection of O2 at the end of the pulse Duration of O2 injection into the constantpropane pulse. injection of O2 at the endof the pulse then at the start of the pulse Summary Flask1 Flask2 Flask3 Flask4 Flask1 Flask2 Flask3 Flask 4 Flask1 Flask2 Flask3 Flask 4 Number of CYCLES 10 10 10 10 10 10 10 10 10 10 10 10 Duration of the injection of propane 33.3 34.4 34.2 34.6 34.4 26.5 34.2 33.6 34.4 34.3 34.6 35 Duration of the O2 pulsesinjected into the propane pulse 5 10 15 20 20 15 10 5 20 20 20 20 Selectivities (%) Acetaldthyde 0.05 0.03 0.03 0.02 0.02 I 0.04 0.05 0.02 0.02 0.02 0.02 Propanaldehyde 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.0 Acetone 1.33 115 0-96 0.77 0.31 0.49 0.38 0.71 0.74 0.77 0.78 Acrolein 0.12 0.13 0.11 0.10 0.09 0.11 0.11 0.07 0.07 0.07 0.07 Allyll alcohol 0.00 0.00 0.00 0.00 0.00 0.00 0.0 0.00 0.00 0.00 0-00 Allyl acrylate 0.00 0.00 0.00 0.00 0.00 0.00 0.0 0.00 0.00 0.00 0.00 Acetic acid 9.69 8.98 8.60 8.2I 8.52 9.59 10.56 8.24 8018 8-42 8.44 Propionic acid 0.21 0.22 0.21 0-19 0.20 0.23 0.25 0.15 0-21 0.19 0.19 Acrylic acid 44.85 48.11 50-59 31.56 49.94 44.48 41.42 49.59 49-2 5 5\AS 51.34 Carbon monoxide 10.56 10.06 10.34 10.95 11.69 11.41 11.15 12.52 12.27 11.30 11.11 Carbon dioxide 8.99 8.20 7.8O 8.27 9.42 10.11 10.15 9.72 9.54 8.99 9.03 Propylene 24.21 23.12 21.37 19.93 19.80 23-53 25.94 18.34 19.68 18.75 19.02 R:/Brevels/20200/20293US-22/02/05 d) Tests of catalyst C 1) Operating process The apparatus used is that described in Example 11 a). i) Test TC1 5 Catalyst C is tested in the same way as for test TA1. The conditions are the same with the exception of the flow rate of He-Kr which is 4.27 Nl/h and the temperature of the test which is 420 C. ii) Tests TC2 to TC4 In the case of test TC2. the catalyst C is tested under the same conditions and in the same 10 way as for test TA2. In the case of tests TC 3 and TC4. there is simply modification of the content of propane during the oxidation and of oxygen during the regeneration. These three tests were carried out at 420 C and with a flow rate of He-Kr of 4.27 Nl/h. iii) Test TC5 Catalyst C is tested in the same way as for test TA3 (presence of molecular oxygen). 15 The conditions are also identical except for the flow rate of He-Kr which is now 4.27 Nl/h. The temperature is 420 G iv) Test TC6 Catalyst C is tested in the same way as for test TB7. The conditions are identical. v) Test TC7 20 Catalyst C is tested in the same way as for test TBS. The conditions are identical except Ibr the flow rate of He-Kr which is 4.27 Nl/h and the temperature of the test which is 420 C. 2) Results a) Tests TC1 to TC4 The results are shown in the two tables below. 25 It is observed. as for catalyst B, that the selectivity of propionic acid and acetone increases with the partial pressure of propane. i.e. the more the catalyst is reduced the less selective it is. The Knetics of initial oxygen consumption is very fast. then appears to develop as a function of the time. R:/Brevels/20200/20293US-22/02/05 37 Table 12-Test TC1 TC2 TC3 TC4 Conditions in the reactionpropane-O2/He-Kr/H2O 10/45/45 10/45/45 20/45/45 30/45/45 Conditions in regenerationO2/He-Kr/H2O 20/45/45 20/45/45 20/45/45 30/45/45 Comments Standardtest Variation of the duration of thepropane pulse in the mixture Variation of the duration of thepropane pulse in the mixture Variation of the duration of thepropane pulse in the mixture Summary Average Flask4 Flask3 Flask2 Flask6 Flask4 Flask3 Flask2 Flask5 Flask6 Flask4 Flask3 Flask2 Flask5 Flask6 Number of CYCLES 60 15 15 8 8 7 15 15 8 8 6 15 15 £ 8 7 Duration of the injection of propane 12.2 4.45 7.7 12.5 22.2 31.18 4.45 7. IS 12.65 22-5 32.5 4.25 7.4 12.3 21.8 30.4 Yields (%) Acetaldehyde 0.03 0.00 0.00 0.00 0.00 0.01 0.00 0.01 0.01 001 0.01 0.01 0.01 0.01 0.01 0.01 Propanaldehyde 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Acetone 0.16 0.11 0.13 0.15 0.19 0.20 0.17 0.19 0.21 0.23 0.25 0.18 021 0.21 0.21 0-20 Acrolein 0.02 0.00 0.00 0.00 0-00 0.01 0.00 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.01 0-02 Allyll alcohol 0.00 0.00 0.00 0.00 0-00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Allyl acryate 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0-00 Acetic acid 2.74 3.42 2.77 2.80 2-52 2.19 3.10 2.75 2.42 1.86 1.86 2.75 2.48 1.99 1.49 1.31 Propionic acid 0.04 0.04 0.04 0.04 0.04 0.04 0.05 0.04 0.04 004 0.04 0.04 0.04 0.04 0.03 0.03 Acrylic acid 16-06 24.30 19.19 15.15 11.46 9.12 16.65 13.41 9.91 6.69 6.31 13.29 10.33 7.66 5.11 4.12 Carbon monoxide 4.71 6.30 5.31 4.77 3-27 2.82 4.22 3.54 2.73 1.77 1.52 3.81 2.93 2.12 1.39 1.23 Carton dioxide 3.25 3.79 3.01 3.24 2.32 2. 11 2.81 2.67 2.28 1.64 1-39 2.90 2.49 2.00 1.36 1018 Propylene 3.60 3.20 3.50 3.59 3.70 3.67 3.70 3.75 3.76 3.69 3-47 3.82 3.74 3.78 3.56 3.36 Propane 69.81 59.24 65.71 70.26 76.66 79.99 68.93 73.96 78.60 34.11 85-42 73.47 78-08 82.48 86.82 88.72 Carton balance (%) 100.4 [00-4 99.(5 100.0 100.2 100.2 99.6 100.3 100.0 100.0 100.3 100.3 100.3 100.3 100.0 100.2 R:/Brevels/20200/20293US-22/02/05 Table 12-Test | TC1 TC2 TC3 TC4 TC4 Conditions in the reactionpropane-O2/He-Kr/H2O 10/45/45 10/45/45 20/45/4: 30/45/45 Conditions in regenerationO2/He-Kr/H2O 20/45/45 20/45/45 20/45/4. 30/4545 Comments Standardtest Variation of the duration of thepropane pulse in the mixture Variation of the duration of thepropane pulse in the mixture Variation of the duration of thepropane pulse in the mixture Summary Average Flask4 Flask3 Flask2 Flask5 Flask6 Flask4 Flask3 Flasfc2 Flask5 Flask6 Flask4 Flask3 Flask2 Flask5 Flask6 Number of CYCLES 60 15 15 8 8 7 15 15 8 8 6 15 15 8 8 7 Duration of the injection of propane 12.2 4.45 7-7 12.5 22.2 31.8 4.45 7.6 12.65 22.5 32.5 4.25 7.4 12.3 21,5 30.4 Selectivitles(%) Acetaldebyde 0.09 0.00 0.00 0,00 0.00 0,06 0,00 0.06 0.06 0.08 0-07 0,05 0-06 0.06 0.06 0.08 propaneldebyde 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0,00 0.00 0.00 0.00 0.00 0.00 0.00 Acetone 0.53 0.27 0.37 0.52 0-82 1.01 0,56 0.74 1.01 1.42 1.70 0.67 0,96 1.19 1.56 1.77 Acrolein 0.06 0.00 0.00 0.00 0.00 0.07 0.00 0.07 0.09 0.10 0.12 0-06 0.09 0.10 0.10 0.13 Allyl alcohol 0.00 0,00 0.00 0.00 0.00 0.00 0,00 0.00 0.00 0.00 0.00 0.00 0,00 0.00 000 0.00 Allyl acrylate 0.00 0.00 0,00 0.00 0-00 0.00 0.00 0,00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Acetic acid 8.97 8..30 8-15 9.40 10.71 10.87 10.11 10.42 11.31 11 .65 12.48 10,25 11.14 11.17 11.34 11.44 Propionic acid 0.14 0.09 0.11 0.13 0.18 0.89 0.15 0-16 0.19 0.23 0.25 0.17 0.13 0,20 0.24 0.22 Acrylic acid 52.46 59.03 56.53 50.95 48-76 45.19 54.23 50.83 46.36 42,00 42,43 49.54 46.43 42,99 38.75 Carbon monoxide 15,38 15.31 15.65 16.03 13.92 13.98 13.73 13.41 12.75 11.10 10.23 14.21 13.15 11.88 10,56 10.74 Carbon dioxide 10.63 9.21 8.S6 10.91 9-67 10.46 9.16 10.11 10.67 10.29 9.37 10.80 11, 18 11.20 10.34 10.34 Propylene 11.76 7.78 10.32 12,06 15.73 18.16 12,06 14-21 17.57 23.15 23,34 14,25 16,81 21.21 27.05 29.33 Quantity of O2 consumedKgO/kg catalyst) 0.627 0.310 0.434 0,628 0.836 1.019 0.428 0625 0.825 1.033 1.363 0.548 0.776 0,993 1.220 1.454 µmole propane for 1 cycle 135.3 49.3 85.4 138.6 246.1 352.5 95,0 162.3 270.1 480.5 694.0 138.0 240.3 399-5 708.0 987.3 propane conversion ratioKg catalyst/kg converted propane) 2783 5655 3884 2759 1980 1612 3854 2693 1969 1490 1125 3108 2160 1626 3220 1022 39 b)Tests TC5 to TC7 The results are shown in the three tables below. It is observed that the addition of oxygen at the start of the propane pulse. rather than 5 at the end of the pulse. leads to a small gain in acrylic acid selectivity. which appears to result from a lower COX selectivity. R:/Brevels/20200/20293US-22/02/05 ■40 Table 13 - Test TCS TC6 TC7 Conditions in the reactionpropane-O2/He-Kr/H2O 30+30/45/45 3O+30/45/45 30+30/45/45 Conditions in regeneration O2/He-Kr/H2O 20/45/45 20/45/45 20/45/45 Comments Variation in the duration of the O2injection in the propane pulse - O2injection at the start of the pulse Variation in the duration of the O2injection in the propane pulse - O2injection at the end of the pulse Duration of the O2 injection in theconstant propane pulse - O2 injectionat the end of the pulse tben at thestart of the pulse Summary Flask1 Flask2 Flask3 Flask4 Flask1 Flask2 Flask3 Flask4 Flask1 Flask2 Flask3 Flask4 Number of CYCLES 10 10 10 10 10 10 10 10 10 10 10 10 Duration of the injection of propane 32.6 33 32.' 34 34.9 35.4 34.7 33.6 33.9 34.5 33.9 34 Duration of the O2 pulses injected into thepropane 5 10 15 20 20 15 10 5 20 20 20 20 Yields (%) Acetaldehyde 0.0 0.0 0.0 0.0 0-0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Propanaldehyde 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Acetone 0.3 0.2 0-2 0.2 0.1 0.I 0.2 0.2 0.i 0.1 0.2 0.2 Acrolein 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Allyl alcohol 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 00 0.0 Allyl acryiate 0-0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Acetic acid 1.6 1.5 2.0 2.0 l.8 1.6 l.6 1.5 1.9 1.9 2.0 2.0 Pripionic acid 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Acrylic acid 6.7 8.6 10.2 11.6 10.5 7.9 611 5.1 11.4 11.1 li.y 12.0 Carton monoxide. 1.8 2.1 2.4 2.7 2.3 2.4 2.0 1.7 3.1 2 .9 2-8 2.9 Carbon dioxide 1-6 1.8 2.0 2.1 2.3 2.0 1.7 1.5 2.5 2.3 2.4 2.3 Propylene 3.6 3.9 4.1 4.2 4.1 3.9 3.7 3.4 4.1 4.2 4.2 4.3 Propane 84.4 81.5 79.0 77.3 78.2 82.2 84.1 86.6 76.5 77.6 76.4 76.1 Carbon balance. (%) 100.1 100.0 99.9 100.2 100.1 100.2 100.0 100.1 99.8 100.1 100.0 99.8 R:/Brevels/20200/20293US-22/02/05 41 Table 13- Test TCS TC6 TC7 Conditions in the reactionpropane-O2/He-Kr/H2O 30+30/45/45 30+30/45/45 30+30/45/45 Conditions in regeneration O2/He-Kr/H2O 20/45/45 20/45/45 20/45/45 Comments Variation in the duration of the O2injection in the- propane pulse - O2injection at the start of the pulse Variation in the duration of the O2injection in the propane pulse -O2injection at the end of the pulse Duration of the O2 injection in the:onstant propane pulse - O2 injectionat the end of the pulse then at the starof the pulse Summury Flask 1 Flask 2 Flask 3 Flask 4 Flask 1 Flask 2 Flask 3 Flask 4 Flask 1 Flask 2 Flask 3 Flask 4 Number of CYCLES 10 10 10 10 10 10 10 10 10 10 10 10 Duration of the injection of propane 32.6 33 32.9 34 34.9 35-4 34.7 33.6 33.9 34.5 33.9 34 Duration of the oxygen pulses injected into thepropane (s) 5 10 15 20 20 15 10 5 20 20 20 20 Selectivities(%) Acetaldehyde 0.08 0.06 0.05 0.05 0.05 0.05 0.07 0.09 0.05 0.04 0.04 0.04 Propanaldehyde 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Acetone 1.36 1.09 0.88 0.73 0.64 0.81 1.13 1.53 0.60 0.64 066 0.67 Acrolein 0.13 0.11 0.10 0.10 0.10 0.10 0.13 0.14 0.11 0.11 010 0.10 Allyl alcohol 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Allyl acryiate 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 000 0.00 Acetic acid 10.50 9.81 9.35 8.90 8.45 8.78 9.85 11.20 8.21 8.34 8.57 5.58 Propionic acid 0-20 0.19 0.19 0.18 0.17 0.18 0.21 0.22 0.16 0.17 0.16 0.17 Acrylic acid 42.8 46.5 49.0 50.7 48.1 43.9 41.8 37.7 48.9 49.1 50.7 50.5 Carbon monoxide 11.5 11.16 11.7 11.7 13.4 13.3 12.7 123 13.3 12.8 11. 8 12.0 Carbon dioxide 10.2 9.6 9.4 9.3 10.4 11.1 11.0 11.4 10.9 10.4 10.0 9.9 Propylene 23.1 21.0 19.4 13.-3 18.6 21.7 23.1 25.4 17.8 18.5 18.0 18.0 R:/Brevels/20200/20293US-22/02/05 42 Table !3-Test TC5 TC6 TC7 Conditions in the reactionpropane-O2/He-Kr/H2O 30+3O/45/45 3Q+3W45/45 30+30/45/45 Conditions in regenerationO2/He-Kr/H2O 20/45/45 10/45/45 20/45/45 Comments Variation in the duration of theO2injection in the propane pulse - O2injection at the start of the pulse Variation in the duration of the O2injection in the propane pulse - O2injection at the end of the pulse Duration of the O2 injection in theconstant propane pulse - O2 injectionat the end of the pulse then at thestart of the pulse Summary Flask 1 Flask 2 Flask 3 Flask A Flask 1 Flask2 Flask 3 Flask 4 Flask 1 Flask 2 Flask 3 Flask 4 Number of CYCLES 10 10 10 10 10 10 10 10 10 10 10 10 Duration of the injection of propane 32.6 33 32.9 34 34.9 35.4 34.7 33.6 33-9 34.5 339 34 Duration of the 02 pulses injectedinto the propane (s) 5 10 15 20 20 15 10 5 20 20 20 20 Quantity of oxygen consumedKg O/Kg catalyst) 2.25 2.69 3.08 3.52 353 2.91 2.4-7 2.00 3.67 3.56 3.62 3.66 µmoles of propane for 1 cycle 1059 1072 1104 1133 1150 1127 1091 1101 1120 1101 1104 µmoles of O2 added per cycle 158 317 475 634 634 475 317 158 634 634 634 634 µmoles of oxygen consumed(products formed) /cycle 704 843 963 1101 1104 911 773 625 1153 1119 1140 1152 Propane conversion ratio(kg catalyst/kg converted propane) 681 504 467 454 556 740 435 457 433 427 [ R:/Brevels/20200/20293US-22/02/05 43 Example 12 Preparation of the precursor of a catalyst of formula: Mo1V0.3Sb0.15Nb0.1Si0,. 76Ox Stage 1: dissolution-precipitation Solution A 5 The assembly illustrated in Figure 2 is used which comprises a 1 litre reactor of the SVL type equipped with a stiner connected to a motor and a water cooler containing Raschig rings. A nitrogen supply is installed on the reactor and a gas washing bottle is placed at the outlet of the cooler. The heating is ensured by a thermostatically controlled oil bath. 10 12.3 g of ammonium metavanade (AMV) (i.e. 0.1052 mole of vanadium) are placed in solution in 260ml of demineralised water. in the reactor. under stirring. A yellow solution is obtained. 7.7g of Sb2O3 (i.e. 0.0528 mole of antimony) are added to the limpid solution. then 61.8 g of ammonium heptamolybdate (AHM) (i.e. 0.3501 mole of molybdenum) are added. After the addition of AHM. the reactor is placed under 15 nitrogen flow. the reaction is maintained under stilting. at reflux. for 4 hours. A black solution is gradually obtained; the reaction is considered lo be complete after 1 hour. The solution obtained is called solution A. Solution B 6.1g (0.0532 mole) of an aqueous solution of H2O2 at 30% by weight is dissolved in 20 98 g of water. and are then added to solution A over 2 to 3 minutes. The solution becomes limpid orange in 4-5 minutes. Then 40 g of Ludox silica (0.2663 mole of Si) are added in one go and the solution becomes cloudy. The solution formed is called solution B. Solution C 25 Solution C is prepared at the same time as solution A: 13.2 g (0.1047 mole) of oxalic acid and 5.9 g of niobic acid (i.e. 0.0351 mole of Nb) are dissolved under stirring at 80 C. in 100 g of water. over 2 hours. This solution is then centrifuged at 6200 r.p.in. for 12 minutes. in order to obtain a limpid solution C Then. solution C is added to solution Bf in one go. A fluid gel is obtained which is 30 orange then yellow. Stirring is continued for 30 minutes under nitrogen flow. under reflux. 2) Stage 2: drying R:/Brevels/20200/20293US-22/02/05 The gel obtained previously is dried in a ventilated oven. on Teflon-covered plates. overnight. at 130 C 104.2 g of dry precursor are recovered. This precursor. hereafter called PI, is in the form of sheets. black on the top with a green film underneath Example 13 5 Preparation of the precursors P2 to PI 5 The process is carried out as indicated in Example 12. except for the conditions shown in the following Table 14. in which the appearances of the precursors obtained are also shown. R:/Brevels/20200/20293US-22/02/05 45 TABLE 14 Summary of the precursor synthesis Solution A Solution B; addition of oxygenated water Solution C Precursor Mounting Sb/Mc Duration of stirringof Solution (Mo.V1Sb) in hours H2O2/Mn Time ofintroductionOf H2O2 Colourchange Limpidity Remark Si/Mo Remark Appearance ofprecutsor P2 Three necked flaskwith magnetic stirrer 0.15 5 0-15diluted 5h orange No yellow precipitate 0.76 black, greenunderneath P3 SVL 0. 15 5 0.15diluted 2mn orange Yes transferred to a heated three-necked flask before introductionof H2O3. still limpid 0.76 black with sornetrace of green P4 SVL 0.15 3 0-15diluted 2-3mn orangeiin 5 mn Yes transferred to a heated three-necked flask before introductionof H2O3 0.76 Ox/Mo: 0.2S black P5 SVL 0.15 2 0.15diluted 2-3mn orangein 5-7mn Yes transferred to a heated three-necked flask before introductionof H2O3 0-7' Ox/Mo: 0.28 black PI SVL 0.15 4 0.15diluted 2-3mn orangein 2-3mn Yes no transfer 0.76 blajtk P6 SVL 0.15 0.15diluted 2-3mn orangein 4-5mn Yes 0.7(5 Heated for 1 hW P7 SVL 0.15 4 0.15diluted orangein 2-3mn Yes 0.76 black. greenundemeatli P8 SVL 0.23 4 0.23diluted In two gnes cloudyorange no + a few drops of H2O2 0.76 black. greenunderneath P9 SVL 0-23 4 0.23diluted 1 -2 minutes browngreen no 0.76 black. greenunderneath P10 SVL 0.23 5 0.23diluted NA blackdarkpurple no addition of H2O2 in solution C 0.76 solution CatMwj directlyitforetbe siliti black. finerthan usual P11 SVL 0.15 4 0.15diluted orangein 5minutes yes 0.7' no niobium.heated to 50 C black. darkkhaki greenunderneath R:/Brevels/20200/20293US-22/02/05 46 TABLE 14 (continued) Solution A Solution D: Addition of oxygenated water Solutuion C i Precursor Mounting Sb/Mo Duration of stirriingof the solution(Mo.V1 Sb) in hours H2O2/Mo Time ofintroductionof H2O2 Colourchange Limpidity Remarks Remark Appearance ofprecursor SVL 0.15 4 0.15diluted Orange Yes +a few drops of H2O2 0.76 P13 SVL 0. 15 4 0.15diluted orang e yes, thencloudy new bottle, same batch + 20drops H2O2 0.76 heated for1hl5 black, greenunderneath.entirely greenarea PI4 SVL 0.23 4 0.23diluted slow. orang e yes +20 drops of H2O2 0.76 fine black.greenunderneath P15 SVL 0.15 4 0.15diluted slow oran ge yes +2drops of H2O2 0.93 new batch ofoxalic acid black withyellow parts R:/Brevels/20200/20293US-22/02/05 Ex ample .14 Precalcination and calcination of the precursors PJ to P15 The precalcinations and the calcinations are carried out in combustion boats under flow of air and of nitrogen respectively. in steel capacitors. These capacitors are 5 directly installed in muffle furnaces and the air or nitrogen is supplied via the flue. An internal thermometer well allows precise monitoring of the temperature. The cover prevents air returning towards the catalyst (see Figure 3)- The precursors P1 to P15 obtained in Examples 12 and 13 arc prccalcinated at 300 C. for 4 hours. under air flow. then calcinated at 600 C, for 2 hours under nitrogen flow 10 of 50 ml/mn/g in a muffle furnace. The calcinations The following conditions for heat treatment of the precursors are studied: - calciner; - flow rate of precalcination air in ml/min/g; - calcination temperature variation gradient in C/min. 15 These conditions are shown in Table 15 below. R:/Brevels/20200/20293US-22/02/05 48 TABLE 15 Heat treatment of the precursors (for weights of 25 to 30g) Catalyst Precursor Precalcination flow rate | Calcination slopes under N2 ( C/min) (ml/min/g) 1 2 5 10 C2 P2 50.4 C3 P3 47 C4 P4 47 C5 P5 47 Cl PI 48.5 C6 P6 45.8 | C7 P7 44.9 C8 P7 45 C9 P7 47.2 C10 P7 47 C11 P7 0 C12 P7 10 C13 P7 20.1 C14 P7 5l.6 C15 P8 46.9 C16 P8 47.1 CI7 P8 45.5 C18 P8 48 C19 P8 22.15 C20 P8 10.55 C21 P8 20.9 C22 P8 10.5 C23 P9 45.2 C24 P10 47-2 C25 P11 46 C26 P12 45.7 C27 P13 47.5 C28 P14 47 C29 P15 50-7 C30 P15 50.3 C31 P15 34.5 C32 P15 18.7 10 Example 15 Tests of the catalysts obtained a) Apparatus In order to simulate the process according to the invention. simulations were carried out in the laboratory in a laboratory fixed bed reactor. The following are therefore loaded from the bottom to the top of a vertical reactor with cylindrical shape and made of pyrex: R:/Brevels/20200/20293US-22/02/05 49 - a first height of 1 ml of silicon carbide in the form of particles of 0.125 mm in diameter. - a second height of 8 g of catalyst in the form of particles of 0.02 to 1 mm diluted with 10 ml of silicon carbide in the form of particles of 0.125 mm in 5 diameter. a third height of 1 ml of silicon carbide in the form of particles of 0.125 mm in diameter. and - a fourth height of silicon carbide in the form of particles of 1.19 mm in diameter. so as to fill all of the reactor. 10 b) Test conditions The catalyst is simultaneously supplied with propane and with oxygen. The helium acts as diluent gas and water is vaporized in the gaseous flow. The catalysts are tested at 380 C, 390 C and 400 C with a ratio propane/O2/He- 15 Kr/H20 of 10/10/45/45. The total flow rate of the gaseous flow rises to 8.65 Nl/h. The reactor is placed in an isothermal furnace. It is supplied with propane. oxygen and helium by mass flow meters. An HPLC pump and a vaporizer ensure the production of vapour. Thermocouples are placed in the furnace to allow their regulation. and in the reactor 20 to measure the '"hot spot". i.e. the highest temperature in the catalyst bed. c) Results of the tests Only the results of the tests carried out at 400 C are given. It is at this temperature that it was observed that the best results were generally obtained. The results of the tests are recorded in Tables 16 and 17 below in which the yields are 25 only calculated on the basis of the routine chromatographic analyses. The selectivities are calcuiated as being the yield of a given product over the sum of the yields of products. The carbon balances are used to ensure the homogeneity of the data. They are considered to be acceptable for values comprises between 95 and 105 %. 30 The yield calculations are based on the krypton content of the gas. Measurement of the flow rate of dry gas at the outlet of the reactor allows calculations to he made based on this flow rate of gas. The yield calculations can thus be validated. R:/Brevels/20200/20293US-22/02/05 50 The yields and selectivities of each of the products assayed are given. as well as the yield of acid. obtained by assay with 0.1N soda. This is a pseudo-yield obtained supposing that all the acids formed have 3 carbon atoms. R:/Brevels/20200/20293US-22/02/05 TABLE 16 Summary table of the yields produced by the catalysts Yields . TTUc (%) Catalyst Reaction temp.(C) Hotspottemp.(C) TTG(ΣTTU) TTG O2(ΣTTU) Carbon balance Oxygen balance Acetaldehyde Propanaldehyde Acetone Acrolien Allyl alcohol Allyl acryiate Acetic acid Propionic acid Acrylic acid CO CO2 Propylene Propane CO+CO2 Acid perassay C5 400 413 19.5 42.8 100.9 101.6 0.0 0.0 0.1 0.0 0.0 0.0 2.4 0.1 7.3 2.3 2.2 4.6 81.4 5.0 10.1 C4 400 417 18.2 41.4 97.2 99.1 0.0 0.0 0.1 0.0 0.0 0.0 2.3 0.1 6.5 3.0 2.1 4.0 78.9 5.2 10.2 C1 400 413.6 16.9 36.4 100 3 00.3 0.0 0.0 0.1 0.0 0.0 0.0 1.7 0.1 6.1 2.5 l.8 4.4 83.4 4.3 9.1 C3 400 411.9 18.3 38.9 101.0 100.3 0.0 0.0 0.1 0.0 0.0 0.0 2.0 0.1 7.4 2.4 1.8 4.6 82.7 4.2 9.9 C2 400 410 16.0 32.5 99.3 99.1 0.0 0.0 0.2 0.1 .0 0.0 1.5 0.1 6.6 1.9 1.4 4.2 83.3 3.3 8.7 C6 400 424 20.4 47.6 102.5 99.7 0.0 0.0 0.1 0.0 0.0 0.0 2.3 0.1 7.0 3.6 2.7 4.5 32.1 6.4 10.6 C7 400 411 17.3 35.5 100.2 100.4 0.0 0.0 0.1 0.0 0.0 0.0 1.7 0.0 7.3 2.1 1.5 4.5 82.9 36 9.7 C8 400 409.3 16.1 33.0 99.2 94.1 0.0 0.0 0.1 0.0 0.0 0.0 1.6 0.! 6.1 2.1 1.5 4.5 83.1 3.6 8.7 C9 400 416 16.1 34.0 104.3 99.9 0.0 0.0 0.2 0.0 0.0 0.0 1.7 0.1 5.9 2.2 1.7 4.3 88.2 3.9 8.8 C10 400 420 19.1 41.6 103.3 00.0 0.0 0.0 0.2 0.0 0.0 0.0 2.0 0.1 7.7 2.8 2.0 4.3 84.7 4.8 10.6 C12 400 410.7 15.7 32.2 97.3 97.5 0.0 0.0 0.1 0.0 0.0 0.0 1.6 0.1 5.6 2.1 1.5 4.7 81.6 3.6 8.2 C14 400 405.2 17.7 36.5 99.3 99.6 0.0 0.0 0.3 0.0 0.0 0.0 1.9 0.2 7.7 2.1 1.5 4.1 81.5 3.6 10.1 C26 400 411 17.0 361 99.4 99. 8 0.0 0.0 0.1 0.0 0.0 0.0 1.9 0.1 6.3 2.3 1.6 4.1 82.5 3.9 9.9 C30 400 409.5 13.5 25.5 99.4 99.8 0.0 0.0 0.1 0.0 0.0 0.0 1.1 0.0 6.1 1.3 0.9 4.0 85.9 2.2 7.9 C32 400 410 17.0 32.3 99.9 99.8 0.0 0.0 o.1 0.1 0.0 0.0 1.1 0.1 9.0 1.4 0.9 4.3 82.9 2.3 10.8 C23 400 410 15.6 29.6 100.6 100.9 0.0 0.0 0.1 0.0 0.0 0.0 1.2 0.1 7.5 1.4 1.0 4.4 85.0 2.4 8.9 C16 400 408.8 13.3 25.3 101.0 98.7 0.0 0.0 0.1 0.1 0.0 0.0 1.0 0.1 5.6 1.4 0.9 4.0 87.8 2.4 7.5 C17 400 411.1 20.3 42.9 99.2 98.9 0.0 0.0 0.2 0.1 0.0 0.0 1.8 0.1 9.7 2.4 l.8 4.2 78.9 4.2 12.3 C18 400 411.1 20.1 42.5 99.0 98.5 0.0 0.0 0.2 0.0 0.0 0.0 1.8 0.1 9.6 2.4 9.3 4.2 78.9 4.2 12.3 C28 400 410 16.6 33.5 102.9 99.8 0.0 0.0 0.1 0.0 0.0 0.0 1.4 0.1 7.4 1.9 1.4 4.4 86.4 3.2 9.4 C25 400 405 3.9 4.9 98.9 99.8 0.0 0.0 0.0 0.0 0.0 0.0 0.2 0.0 0.6 0.3 0.2 2.3 95.0 0.4 1.0 C24 400 40 .8 12.3 21.1 106.4 104.3 0.0 0.0 1.2 0.1 0.0 0.0 0.6 0.1 5.9 0.7 0.5 3.3 54.1 1.2 7.4 C27 400 410.4 16.0 31.1 99.6 99.8 0.0 0.0 0.1 0.0 0.0 0.0 .4 0.1 7.4 1.6 1.1 4.3 83.6 2.7 9.6 R:/Brevels/20200/20293US.22/02/05 52 TABLE 17 Summary table of the selectivities of the catalysts Selectivities (%) Catalyst Reaction temp.(C) Hotspottemp.(C) TTG(ΣTTU) TTG O2(ΣTTU) Carbon balance Oxygen balance Acetaldehyde Propanaldehyde Acetone Acrolien Allyl alcohol Allyl acryiate Acetic acid Propionic acid. Acrylic acid CO CO2 Propylene C5 400 413 19.5 42.8 100.9 101.6 0.0 0.0 0.6 0.1 0.0 0.0 12.5 0.5 37.2 14.4 11.0 23.6 C4 400 417 18..2 11.4 97.2 99.1 0.I 0.0 0.8 0.2 0.0 0.0 12.6 0.4 35.6 16.7 11.7 21.8. C1 400 413.6 16.9 36.4 100.3 100.2 0.0 0.0 0.7 0.1 0.0 0.0 10.4 10.4 10.4 10.4 10.4 10.4 C3 400 411.9 18.3 38.9 101.0 100.8 0.0 0.0 0.7 0.1 0.0 0.0 10.7 0.3 40.3 L3.3 9.8 24.9 C2 400 410 16.0 32.5 99.3 99.1 0.3 0.0 1.0 0.5 0.0 0.0 9.2 0.8. 41.2 12.1 8.6 26.3 C6 400 434 20.4 47.6 102.8 99.7 0.0 0.0 0.1 0.2 0.0 0.0 11.3 0.3 34.4 17.8 13.3 21.8 C7 400 411 17.3 35.5 100.2 100.4 0.0 0.0 0.8 0.1 0.0 0.0 0.6 0.3 42.1 12.2 8.8 26.2 C8 400 409.3 16.1 33.0 99.2 94.1 0.0 0.0__| 0.9 0.2 0.1 0.1 10.0 0.4 37.3 13.2 9.3 28.0 C9 400 416 16.1 34.0 104.3 99.9 0.0 0.0 1.2 0.1 0.0 0.0 10.4 0.5 37.0 13.5 10.7 26.5 C10 400 430 19.1 41.5 103.3 100.0 0.0 0.0 0.8 0.1 0.0 0.0 10.6 0.4 40.6 14.5 10.5 22.5 C12 400 410.7 15.7 32.2 97.3 91.5 0.0 0.0 0.9 0.2 0.0 0.0 10.3 0.4 35.4 13.4 9.8 29.7 C14 400 405.2 17.7 36.5 59.3 99.15 0.0 0.0 1.6 0.0 0.0 0.0 10.7 1.0 43.2 11.6 8.5 214 C26 400 411 17.0 36.1 99.4 9?.8 0.0 0.0 0.7 0.1 0.0 0.0 11.2 0.3 40.9 13.6 9.4 23.9 C30 400 409.5 13.5 25.5 99.4 99.8 0.1 0.0 0.6 0.1 0.0 0.0 8.2 0.3 45.0 9.6 6.3 29.8 C32 400 410 17.0 32.2. 99.9 99.8 0.0 0.0 0.8 0.1 0.0 0.0 6.7 0.4 52.8 8.1 5.5 216 C23 400 410 15.6 29.6 100.6 100.9 0.0 0.0 0.6 0.1 0.0 0.0 7.4 0.3 43.0 9.0 6.3 28.2 C16 400 408.8 13.1 25.3 101.0 93.7 0.0 0.0 0.7 0.4 0.0 0.0 7.7 0.0 42.4 lO.d 7.1 30.5 CI7 400 411.1 20.3 42.9 99.2 9S.9 0.0 0.0 0.9 0.4 0.0 0.0 3.7 0.7 47.8 11.9 8. 8 20.3 C18 400 411.1 20.1 12.5 99.0 93.5 0.0 0.0 0.9 0.0 0.0 0.0 8.8 0.7 47.6 12.1 8.9 21.0 C28 400 410 16.6 33 5 102.9 98 .8 0.0 0.0 0.7 0.1 0.0 0.0 8.2 0.4 44.9 11.2 8.2 26.3 C25 400 405 3.9 4.9 98.9 0.1 0.1 1.0 0.4 0.1 0.0 5.9 0.6 16.6 7.0 4.0 64.1 C24 400 401 .8 12.3 21.1 106.4 104.3 0.0 0.0 9.9 0.4 0.0 0.0 4.9 0.5 47.9 55 4.3 26.6 C27 400 410.4 16.0 31.1 99.6 99.8 0.0 0.0 0.8 0.2 0.0 0.0 8.5 0.4 46.1 10.0 27.2 R:/Brevels/20200/20293US.22/02/05 53 Example 16 Precursors P16 of the catalyst of formula Mo1V0.3Sb0.15Nb0.1Si0.76Ox are prepared according to the operating process given in Example 12. 5 From these precursors P16. a series of catalysts is prepared which are tested. The precalculation and calcination conditions of the precursor PI 6 are shown in Tables 18 and 19 below. 1) Stage 1: dissolution.precipitation Solution A 10 The assembly illustrated in Figure 2 is used which comprises a 1 litre reactor of the SVL type equipped with a stirrer connected to a motor and a water cooler containing Raschig rings. A nitrogen supply is installed on the reactor and a gas washing bottle is placed at the outlet of the cooler. The healing is ensured by a thermostatically controlled oil bath. 15 30.75g of ammonium metavanade (AMV) (i.e. 0.2629 mole of vanadium) is placed in solution in 650 ml of dematerialized water. in the reactor. under stirring. A yellow solution is obtained. 19.25 g of Sb2Os (i.e. 0.1321 mole of antimony) are added. with 154.5 g of ammonium heptamolybdate (AHM) (i.e. 0.8753 mole of molybdenum) are added. After the addition. the reactor is placed under nitrogen flow. 20 the reaction is maintained under stirring. al reflux. for 4 hours. A black solution is gradually obtained; the reaction is considered to be complete after 1 hour. The solution obtained is called solution A. Solution B 15.25 g (0.1346 mole) of an aqueous solution of H2O2 30% by weight is dissolved 25 in 90 g of water. and is then added to solution A over 5 minutes. The solution becomes limpid orange in 4.5 minutes. Then 100 g of Ludox AS 40® silica (0.6667 mole of Si) is added in one go and the solution becomes slightly cloudy. The solution formed iscalledsolution B. Solution C 30 Solution C is prepared at the same time as solution A: 33.0 g (0.261 8 mole) of oxalic acid and 14.75 g of niobic acid (i.e. 0.0877 mole of Mb) are dissolved under Stirring at 66 C. in 250 g of water. Over 2 hours. This solution is then centrifuged at 6200 r.p.m. for 12 minutes. in order to obtain a limpid solution C. R:/Brevels/20200/20293US.22/02/05 54 Then. solution C is added to solution B, in one go. A fluid gel is obtained which is orange then yellow. Stirring is continued for 30 minutes under nitrogen flow. under reflux. 21 Stage 2: drying 5 The gel obtained previously is dried in a ventilated oven. on Teflon.covered plates. overnight. at 130 C 259 g of dry precursor are recovered. This precursor is in the form of sheets. black on the top with a green film underneath. Thus the precursor is obtained which is hereafter called P16. Table 18 shows the yields of carbon (TTUc). with TTGC =ΣTTUC and TTG02 . 10 ΣTTU02. the acidities measured by assay with soda. the carbon and oxygen balances. Table 19 shows the carbon selectivities. R:/Brevels/20200/20293US.22/02/05 55 TABLE 18 Yields of the products obtained during the catalyst tests Yeilds.TTUc (%) Catalyst Cancination temp(C) Flow rate of air(ml/mn/gca) cn temperature(C) ol temperature(C) TTG=total TTU TGO1total TTU C balance O balance Acetaldehyde Propanaldehyde Acentene Acrolien Allyl alcohol Allyl acrylate 'Accitic acid Propionic acid Acrylic acid CO CO2 Propane Propane CO+CO2 Acid per assay C33 2 80 0 400 412 16.5 35.0 98.4 02.1 0.0 0.0 0.1 0.0 0.0 0.0 1.9 0.1 5.3 2.6 1.9 1.6 81.9 4.5 8.3 C34 280 10.6 400 411 15.6 31.6 98.8 03.2 0.0 0.0 0.1 0.0 0.0 0.0 1.5 0.1 5.E 2.0 1.5 4.5 83.2 3.6 8.1 C35 390 0 400 412 16.5 34.5 99.3 03.0 0.0 0.0 0.! 0.0 0.0 0.0 1.7 0.1 5.7 2.4 1.6 4.6 82.7 4.2 8.3 C36 290 10.6 400 411 15.5 30.9 98.2 02.1 0.0 0.0 0.1 0.0 0.0 0.0 1.5 0.1 6.0 2.0 1.4 4.5 82.7 3.4 8.2 C37 300 0 400 410 14.4 28.1 99.6 98.1 0.0 0.0 0.l 0.L 0.0 0.0 1.2 0.1 5.5 1.7 1.3 1.5 85.2 2.9 7.9 C38 300 10 400 411 15.7 32.2 97.3 37.5 0.0 0.0 0.1 0.0 0.0 0.0 1.6 0.1 5.0 2.L 1.5 4.7 81.6 3.6 8.2 C39 300 20.1 400 413 16.7 34.4 98.1 01.6 0.0 0.0 0.1 (i.0 0.0 0.0 1.6 0.1 6.7 2.1 1.6 1.5 41.4 3.7 9.2 C40 300 51.6 400 405 17.7 36.5 99.3 99.6 0.0 0.0 0.3 0.0 0.0 0.0 1.9 0.2 7.7 2.1 1.5 4.1 81.5 3.6 10.1 C41 320 0 400 414 23.5 48.7 99.5 03.1 0.0 0.0 0.2 0.0 0.0 0.0 2.1 0.1 12.8 2.4 1.7 4.2 76.0 4.2. 15.5 C42 320 0 400 438 29.6 67.3 98.7 01.6 0.0 0.0 0.1 0.0 0.0 0.0 2.6 0.0 15.0 4.3 3.1 4.5 69.0 7.4 18.5 C43 310 10 400 414 20.5 44.2 0.00 02.5 0.0 0.0 0.2 0.0 0.0 0.0 1.8 0.1 11.3 2.3 1.7 4.3 78.4 .9 13.8 C44 280 21.1 400 413 20.5 45.6 99.5 01.8 0.0 0.0 0.2 0.0 0.0 0.0 2.0 0.1 9.5 2.5 1.9 4.3 79.1 1.4 12.9 C45 290 19.1 400 414 16.9 35.7 96.3 95.8 0.0 0.0 0.0 0.0 0.0 0.0 [.6 0.1 7.2 2.1 1.6 4.2 79.4 3.7 9.7 C46 320 19.2 400 413 8.1 39.4 99.2 55.7 0.0 0.0 0.0 0.0 0.0 0.0 1.7 0.0 8.8 2.1 1.5 3.9 81.2 3.6 11.2 C47 280 49.2 400 415 18.3 39.8 01.1 99.9 0.0 0.0 0.1 0.0 0.0 0.0 1.6 0.1 8.6 2.2 1.6 1.2 82.8 8.8 11.0 C48 290 52.9 400 414 20.9 46.7 99.1 01.8 0.0 0.0 0.1 0.0 0.0 0.0 2.0 0.1 10.1 2.5 1.9 4.2 78.2 1.4 12.9 C49 320 51.6 400 412 16.1 36.2 98.0 99.1 0.0 0.0 0.0 0.0 0.0 0.0 1.8 0.0 6.4 1.3 1.6 8.8 81.9 .9 9.0 R:/Brevels/20200/20293US.22/02/05 56 TABLE 19 Selectivities of the products obtained in the catalyst tests Selectivities (%) Catalyst Cancination temp(C) Flow rate of air(ml/mn/gca) cn temperature(C) on temperature(C) TTG=total TTU TTO2=total TTU C balance O balance Acetaldehyde Propanaldehyde Acentene Allyl alcohol Allyl acrylate Accitic acid Acrylic acid CO CO2 C33 280 0 400 412 16.5 35.0 98.4 102.1 0.0 0.0 0.7 0.I 0.0 0.0 11.5 0.3 32.2 15.7 11.6 27.8 C34 280 10.6 400 411 15.6 31.6 98.B 103.2 0.1 0.0 0.9 0.1 0.0 0.0 9.7 0.3 37.2 13.1 9.8 25.8 C35 290 0 400 412 16.5 34.5 95.3 103.0 0.1 0.0 0.7 0.1 0.0 0.0 10.5 0.3 34.8 14.6 11.0 27.9 C36 290 10.6 400 411 15.5 309 98.2 102.1 0.0 0.0 0.9 0.1 0.0 0.0 9.6 0.3 38.6 12.8 8.9 2S.9 C37 300 0 400 410 14.4 28.1 99.6 98. 1 0.0 0.0 0.8 0.4 0.0 0.0 8.5 0.7 38.0 11.7 8.7 31.1 C38 300 10 400 411 15.7 32.2 97.3 97.5 0.0 0.0 0.9 0.2 0.0 0.0 10.3 0.4 35.4 13.4 8.8 29.7 C39 300 20.1 400 413 16.7 34.4 98.1 101.6 0.0 0.0 0.9 0.1 0.0 0.0 9.7 0.4 39.9 12 6 9.3 27.0 C40 300 51.6 400 405 17.7 36.5 99.3 99.6 0.0 0.0 1.6 0.0 0.0 0.0 10.7 1.0 43.2 11.6 8.5 23.4 C41 320 0 400 414 23.5 48.7 99.5 103.1 0.0 0.0 0.8 0.1 0.0 0.0 8.8 0.3 54.5 10.4 7.3 17.9 C42 320 0 420 438 29.6 67.3 98.7 101.6 0.0 0.0 0.4 0.1 0.0 0.0 8.7 0.1 50.6 14.5 10.6 15.1 C43 320 10 400 414 21.6 44.2. 100.0 102.5 0.0 0.0 0.7 0.1 0.0 0.0 8. 5 0.3 52.3 10.5 7.7 20.0 C44 280 21.2 400 413 20.5 45.6 99.5 101.3 0.0 0.0 0.8 0.1 0.0 0.0 9.7 0.3 46.6 12.4 9.2 20.9 C45 290 19.1 400 414 16.9 35.7 96.3 95. 8 0.1 0.0 0.2 0.1 0.0 0.0 9.7 0.3 42.8 12.5 9.6 24.7 C46 320 19.2 400 413 18.1 39. 4 99.2 95.7 0.0 0.0 0.3 0.1 0.0 0.0 9.5 0.3 48.4 11.5 8.3 21.7 047 280 49.2 400 415 18.3 39.8 101.1 99.9 0.0 0.0 0.3 0.1 0.0 0.0 9.0 0.3 46.9 11.9 8.7 22.9 C48 290 52.9 400 414 20.9 46.7 99.1 101.8 0.0 0.0 0.3 0.1 0.0 0.0 9.5 0.3 45.3 11.9 9.3 20.3 C49 320 51.6 400 412 16.1 36.2 98.0 99.1 0.1 0.0 0.2 0.1 0.0 0.0 11.5 0.2 39.9 14.4 10.1 23.6 R:/Brevels/20200/20293US.22/02/05 57 It is therefore seen that the best results are obtained with a precalcination at 320 C and under a zero flow rate of air, followed by a calcination at 600 C for 2 hours under a flow rate of nitrogen of 50m/mn/g. 5 58 CLAIMS 1. Process for the production of acrylic acid from propane. characterized in that a gaseous mixture comprising propane. water vapour. and optionally an inert gas 5 and/or molecular oxygen. is passed over a catalyst of formula (I): Mo1VaSbbNbcSic.Ox (I) in which: . a is comprised between 0.006 and 1. inclusive; . b is comprised between 0.006 and 1. inclusive; 10 . c is comprised between 0.006 and 1. inclusive; . d is comprised between 0 and 3.5. inclusive; and . x is the quantity of oxygen bound to the other elements and depends on their oxidation state. in order to oxidize the propane to acrylic acid. and when operating in the presence of 15 molecular oxygen the molar ratio propane/molecular oxygen in the initial gaseous mixture is greater than or equal to 0.5. 2. Process according to claim 1. in which the molar proportions of the constituents of the initial gaseous mixture are as follows: 20 propane/O2/inert gas/H2O (vapour) = 1/0.05.2/1-10/1.10; and preferably 1/0.1.1/1.5/1.5. 3. Process according to claim 1 or claim 2. in which. in the catalyst of formula (I): . a is comprised between 0.09 and 0.8. inclusive; 25 . b is comprised between 0.04 and 0.6. inclusive; . c is comprised between 0.01 and 0.4. inclusive; and. d is comprised between 0.4 and 1.6. inclusive. 4. Process according to one of claims 1 to 3. characterized in that the oxidation 30 reactions are carried out at a temperature of 200 to 500X. 5. Process according to claim 4. characterized in that the oxidation reaction is carried out at a temperature of 250 to 450°C. R:/Brevels/20200/20293US.22/02/05 +59 6. Process according to one of claims 1 to 5. characterized in that the oxidation reactions are carried out at a pressure of l.0lxl04 to 1.01x10' Pa (0.1 to 10 atmospheres). 5 7. Process according to claim 6. characterized in that the oxidation reactions are carried out at a pressure of 5.05x104 to 5.05x10s Pa (0.5.5 atmospheres). 8. Process according to one of claims 1 to 7. characterized in that it is used until there is a reduction ratio of the catalyst comprised between 0.1 and 10 g of oxygen per 10 kg of catalyst. 9. Process according to one of claims 1 to 8. characterized in that once the catalyst has at least partially changed to the reduced state. its regeneration is carried out according to reaction (C): 15 SOLIDreduced + O2 → SOLIDoxidized (C) by heating in the presence of oxygen or a gas containing oxygen at a temperature of 250 to 500 C. for a period necessary for the reoxidation of the catalyst. 20 10. Process according to claim 9. characterized in that the oxidation and the regeneration (C) reactions are carried out in a device with two stages. namely a reactor and a regenerator which operate simultaneously and in which two catalyst loads alternate periodically. 25 11. Process according to claim 9. characterized in that the oxidation and the regeneration (C) reactions are carried out in the same reactor alternating the periods of reaction and regeneration. 12. Process according to claim 9. characterized in that the oxidation and the 30 regeneration (C) reactions are carried out in a reactor with a moving bed. 13. Process according to one of claims 1 to 7. in which: a) the initial gaseous mixture is introduced into a first reactor with a moving catalyst bed. R:/Brevels/20200/20293US.22/02/05 60 b) at the outlet of the first reactor. the gases are separated from the catalyst; c) the catalyst is returned into a regenerator; d) optionally. the gases are introduced into a second reactor with a moving catalyst bed; 5 e) if appropriate. at the outlet of the second reactor. the gases are separated from the catalyst and the acrylic acid contained in the separated gases is recovered; f) if appropriate. the catalyst is returned into the regenerator; and g) the regenerated catalyst from the regenerator is reintroduced into the first 10 reactor and. if appropriate. into the second reactors. 14. Process according to claim 13. in which the first and second reactors are vertical and the catalyst is moved upwards by the gas flow. 15 15. Process according to one of claims 1 to 14. characterized in that the oxidation reactions are carried out with a residence time of 0.01 to 90 seconds in each reactor. 16. Process according to claim 15. characterized in that the oxidation reactions are carried out with a residence time of 0.1 to 30 seconds. 20 17. Process according to one of claims I to 16. characterized in that the propylene produced and/or the propane which has not reacted are recycled to the inlet of the reactor. or if there are several reactors. to the inlet of the first reactor. 25 18. Process according to one of claims 1 to 17. in which the reactor. or when there are several reactors. at least one of the reactors. also comprises a cocatalyst corresponding to the following formula (II): Mo1Bi2FebCocNid'KeSbfTig.SihCaiNbj.TekPbrWmCun. (II) in which: 30 . a' is comprised between 0.006 and 1. inclusive . b' is comprised between 0 and 35. inclusive; . c' is comprised between 0 and 3.5. inclusive; . d' is comprised between 0 and 3.5. inclusive; . e' is comprised between 0 and 1. inclusive; R:/Brevels/20200/20293US.22/02/05 +61 . f is comprised between 0 and 1. inclusive; . g' is comprised between 0 and !„ inclusive; . h' is comprised between 0 and 3.5. inclusive; . i' is comprised between 0 and 1. inclusive; 5 . j' is comprised between 0 and 1. inclusive; . k' is comprised between 0 and !. inclusive; . f is comprised between 0 and 1. inclusive; . m1 is comprised between 0 and 1. inclusive; and . n' is comprised between 0 and 1. inclusive. 10 19. Process according to claim 18. in which the cocalalyst is regenerated and circulates. if appropriate. in the same way as the catalyst. 20. Process according to claim IS or claim 19. in which. in the cocatalyst of 15 formula (II): . a' is comprised between 0.01 and 0.4. inclusive; . b' is comprised between 0.2 and 1.6. inclusive; . c' is comprised between 0.3 and 1.6. inclusive; . d* is comprised between 0.1 and 0.6. inclusive; 20 . e' is comprised between 0.006 and 0.01. inclusive; . f is comprised between 0 and 0.4. inclusive. . g' is comprised between 0 and 0.4. inclusive; . h1 is comprised between 0.01 and 1.6. inclusive . i' is comprised between 0 and 0.4. inclusive; 25 . j1 is comprised between 0 and 0.4. inclusive; . k* is comprised between 0 and 0.4. inclusive; . T is comprised between 0 and 0.4. inclusive; . m' is comprised between 0 and 0.4. inclusive; and . n' is comprised between 0 and 0.4. inclusive. 30 21. Process according to one of claims 18 to 20. in which. a weight ratio of the catalyst to the cocatalyst greater than 0.5 and preferably of at least 1 is used. R:/Brevels/20200/20293US.22/02/05 62 22. Process according to one of claims 18 to 21. in which the catalyst and the cocatalyst are mixed. 23. Process according to one of claims 18 to 21. in which the catalyst and the 5 cocatalyst are present in the form of pellets. each pellet comprising both the catalyst and the cocatalyst. 24. Process according to one of claims 1 to 23. comprising the repetition. in a reactor provided with the catalyst of formula (I) defined in claim 1. and. if 10 appropriate. the cocatalyst of formula (II) defined in claim 18. of the cycle comprising the following successive stages: 1) a stage of injection of the gaseous mixture as defined in claims 1 to 3; 2) a stage of injection of water vapour and. if appropriate. inert gas; 3) a stage of injection of a mixture of molecular oxygen. water vapour and. if 15 appropriate. inert gas; and 4) a stage of injection of water vapour and. if appropriate. inert gas. 25. Process according to claim 24. characterized in that the cycle comprises an additional stage which precedes or follows stage 1) and during which a gaseous 20 mixture corresponding to that of stage 1) but without molecular oxygen is injected. the molar ratio propane/molecular oxygen then being calculated globally for stage 1) and this additional stage. 26. Process according to claim 25. characterized in that the additional stage 25 precedes stage I) in the cycle. 27. Process according to one of claims 24 to 26. characterized in that the reactor is a reactor with a moving bed. R:/Brevels/20200/20293US.22/02/05 |
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| Patent Number | 217470 | ||||||||||||||||||
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| Indian Patent Application Number | 00585/KOLNP/2005 | ||||||||||||||||||
| PG Journal Number | 13/2008 | ||||||||||||||||||
| Publication Date | 28-Mar-2008 | ||||||||||||||||||
| Grant Date | 26-Mar-2008 | ||||||||||||||||||
| Date of Filing | 06-Apr-2005 | ||||||||||||||||||
| Name of Patentee | ARKEMA | ||||||||||||||||||
| Applicant Address | 4/8, COURS MICHELET, F-92800 PUTEAUX, FRANCE. | ||||||||||||||||||
Inventors:
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| PCT International Classification Number | C07C 57/05 | ||||||||||||||||||
| PCT International Application Number | PCT/FR2003/002673 | ||||||||||||||||||
| PCT International Filing date | 2003-09-09 | ||||||||||||||||||
PCT Conventions:
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