Title of Invention

"METHOD FOR CYCLOHEXANOL, CYCLOHEXANONE PRODUCTION"

Abstract Method for cyclohexanol, cyclohexanone production by selective oxidation of cyclohexane to cyclohexanol, cyclohexanone and cyclohexyl hydroperoxide in liquid phase with gases containing oxygen, at the temperature 140 to 180 °C in a reaction flow system consisting of more than one reaction stage, containing circulation cells of the liquid phase as herein described, at the presence of catalyst being solution of salt of metal of the variable valence in cyclohexane, introduced into each or into the majority of reaction stages and next selective decomposition of cyclohexyl hydroperoxide in liquid phase at the temperature 80 to 180 °C run in the last one or in the last reaction stages of oxidation reactor not feed with gas containing oxygen and/or in a separate reactor or reactors of cyclohexyl hydroperoxide decomposition, at the presence of catalyst being solution of salt of metal of the variable valence in cyclohexane characterized in that there is used a catalyst previously diluted, directly before introduction to the reaction system, in oxygen free conditions with pure cyclohexane, not containing the products of its oxidation, from 25 to 1000 times, preferably from 50 to 200 times, from a concentrate having concentration from 0.1 to 2.5 % of metal in cyclohexane solution, that is up to the concentration from 0.0001 to 0.1 %, preferably from 0.0005 to 0.05 %, at the temperature from 10 to 150 °C, preferably from 20 to 100 °C, while before introduction into the separate reactor or 3 reactors of cyclohexyl hydroperoxide decomposition the diluted catalyst is & intensively mixed with the stream of oxidate leaving the oxidation reactor "-"". and introduce into those reactors.
Full Text Method for Selective Oxidation of Cyclohexane to Cyclohexanol, Cyclohexanone and Cyclohexyl Hydroperoxide and Method for Decomposition of Cyclohexyl Hydroperoxide to Cyclohexanol and Cyclohexanone and Equipment for Oxidation of Cyclohexane and Equipment for Decomposition of Cyclohexyl Hydroperoxide.
The object of the invention is a method for selective oxidation of cyclohexane to cyclohexanol, cyclohexanone and cyclohexyl hydroperoxide and a method for decomposition of cyclohexyl hydroperoxide to cyclohexanol and cyclohexanone and equipment for oxidation of cyclohexane and equipment for decomposition of cyclohexyl hydroperoxide.
.
Back ground the big-industrial process of clohexane
Oxidation is performed in a liquid phase with gases containing oxygen, usually at the temperature 140 up to 180°C in a reaction flow system, at the presence of a catalyst being metal salt of variable valence. This process still requires selectivity improvement. !n spite of its several improvements, it is still rare in the so
called classical process (that is proceeding without application of boron compounds) to obtain selectivity higher than being within the range 80-85%. That means that 15-20% of the raw material undergoes transforming into hardly useful or useless byproducts, in spite of keeping low conversion rate (about 3 - 6%), favourable for selectivity but expensive from the energy consumption point of view. This also concerns the Polish process of cyclopean oxidation known under the name...Cyclopes", the specific features of which are: a multistage system of oxidation reaction performing in one multistage reactor, described mainly in the Polish patent description no.64449, and preliminary distribution of the post reaction mixture (oxidant) without its previous neutralization, that is in acid medium, described mainly in the Polish patent description no.72621. A feature of this process is also introduction in one point to the reaction stage, of a catalyst, that is soluble salts of cobalt, iron, chromium and carboxylic acids such as naphthenic or alkyl carboxylic acids in mixtures or separately, of metal concentration from 0.2 up to 10%.
In order to improve the process selectivity there are usually applied the following means:
Change of the process course by dividing it into two stages. In the first stage there proceeds mainly synthesis of cyclohexyl hydroperoxide, while in the second one - its selective decomposition to cyclohexanol and cyclohexanone. An example of such division can be a solution according to the Polish patent no152538, in which decomposition of cyclohexyl hydroperoxide is performed outside the reactor of cyclohexane oxidation for instance in a separate non-aerated apparatus. This method meets difficulties in practical realization, although cyclohexyl hydroperoxide is really more resistant to oxidation than the products of its decomposition, namely cyclohexanol and cyclohexanone. They are mainly difficulties in providing appropriate selectivity of decomposition.
Application of more selective catalysts at the stage of oxidation as well as at the stage of cyclohexyl hydroperoxide decomposition.
At the stage of oxidation, for instance in the

Polish-patent descriptions no152388 and 152389 it is proposed to use two catalysts in mixture or separately (iron and chromium). In the first one the catalyst in the form of solution in cyclohexane of the concentration 10% is introduced into the first stage or
not only into the first reaction stage. It can be also introduced into a pipeline supplying cyclohexane to the oxidation reaction system or into any apparatus from which cyclohexane is taken through this pipeline. The catalyst concentrate is then introduced into the reaction liquid or into so called circulating cyclohexane distilled from the oxidation product, because such cyclohexane is supplied to the reaction system. In each case the catalyst concentrate is introduced into the medium in which there is present oxygen or the products of cyclohexane oxidation. The catalyst of cyclohexyl decomposition is carried to the cyclohexane oxidate, so also this catalyst in the form of concentrate of similar concentration contacts the products of cyclohexane oxidation. While in the Czechpslovakian patent description No. 244986 there is a proposal to use lithium as an promotor. In the Polish patent description no 52081 it is said that catalyst dissolving in cyclohexane is performed up to obtaining concentration at most 2.5% by weight of the catalyst calculated as active metal. However, such high concentrations appeared to be ineffective. In the US patent description nO.3923895 and in the
European patent description EP225731 there is described application of soluble transition metals and
alkyl phosphoric acid salts. Recently published information (for instance D.LVanoppen, D.E.De Vos, M.J.Genet, P.G.Rouxhet, P.A.Jacobs, Angew.Chem. Int.Ed.Engl. 34, no.5, 560-563, 1995) indicate a possibility to apply solid catalysis of the molecular sieve type, in which there proceeds activation of oxygen and cyclohexane leading to alkyl, while the products of oxidation cannot penetrate the interior of such catalyst. These authors' evidence confirm effectiveness of such catalysts evidently improving selectivity of cyclohexane oxidation to cyclohexyl hydroperoxide, however, an obstacle in application is very high cost of the catalyst and technical difficulties in realization of dosing and separation of solid catalyst added in the quantity of a few parts for a million parts of cyclohexane. In the industrial scale of the cyclohexane oxidation process the operations with solid are still very difficult due to a tendency to form

sediments. In the US patent description no.4326084 there was presented a phenomenon of deactivation of the cyclohexane oxidation catalyst consisting in complete decay of activity in the reaction of propagation of free-radical transformation chain and catalyst falling out from the solution measured by decrease of its concentration in the filtrate from 10
below detectable by the authors - 0.1 ppm of metal remaining in the solution in the case of cobaltous 2-ethylcapronate. In the above mentioned description in order to prevent this deactivation there are proposed as a catalyst component, expensive compounds complexing metals cations.
As far as the cyclohexyl hydroperoxide
decomposition stage (hereinafter also called WNCH)
is concerned, it is known that it can be run more
selectively at low temperature in contact with water
alkali solution of transition metal complex. For
instance in the solution according to the German
patent no.3601218 the reaction of decomposition is
run with good efficiency at 80°C for an hour at the
presence of cobalt
ethylenediaminotetramethylenephosphonic complex. However, long reaction time and especially a necessity of diaphragm cooling of large quantity of post-reaction mixture are significant obstacles in application of this method. Besides, this method would not be applied in solutions according to the Polish process ,,Cyclopol" where as above mentioned the preliminary oxidate separation in acid medium takes place. A solution similar to the one described in the German patent was claimed in the European

patent EP 4105 in which there is also used cobalt salt, but without stabilizing complex, in less alkaline water solution, providing that alkylation is performed in two stages. The patent description EP 270468 indicates application of ruthenium complexes in the quantity of a few ppm for WNCH decomposition preferably at the temperature 80-100°C, that is
similarly after .oxidate cooling. In the patent

description EP367326 there is proposed application of complex catalysts containing phthalocyanine or porfirine and metals of the group: cobalt, manganese, chromium, iron, immobilized on carriers so that it is possible to use them again and to separate more easily. However, the price of such catalysts is high and besides, in this case there will also appear problems which in industrial realization create operation with solids.
Summing up, all the catalytic solutions according to the known stage of technology are either too expensive (the cost of catalyst is higher than savings resulting from improvement of the selectivity) or too complicated and troublesome in industrial use or the achieved advantages are insignificant.
Engineering and construction solutions aiming at getting closer to the piston reactor which is

theoretically most favourable for this type of reaction. We can quote here for instance the above mentioned Polish patent no.64449 the object of which is a horizontal flow reactor of cyclohexane oxidation making possible mutistage running of the jrpcess in
~ ~~">.
one apparatus, and the Polish patent no. 152429, the
idea of which consists in forming within the range of one reaction section of such a reactor several zones of circulation around the axis perpendicular to the direction of fluid flow through it. In this case within the range of one zone there appear a few cells of circulating fluid, that is as if a few reaction stages, which additionally brings the reactor closer to the piston type reactor. However, this type of engineering interference into the process, although it gave a positive effect, did not make essential improvement of selectivity possible.
As far as the engineering solutions of the hydroperoxide decomposition process are concerned, there are known applications of additional WNCH decomposition reactors connected directly to the oxidation reactors and working with the same parameters of pressure and temperature as during oxidation, to which there are dosed catalysts, however, hydroperoxide conversion is in such case
usually low. The Polish patent description No. 152388 mentions cyclohexyl hydroperoxide decomposition running in the last section of the oxidation reactor, to which oxidation gases are not added yet, or outside the oxidation reactor in a separate apparatus.
The present invention relates to a method for cyclohexaol, cyclohexanone production by selective oxidation of cyclohexane to cyclohexanol, cyclohexanone and cyclohexyl hydroperoxide in liquid phase with gases containing oxygen, at the temperature 140 to 180 °C in a reaction flow system consisting of more than one reaction stage, containing circulation cells of the liquid phase as herein described, at the presence of catalyst being solution of salt of metal of the variable valence in cyclohexane, introduced into each or into the majority of reaction stages and next selective decomposition of cyclohexyl hydroperoxide in liquid phase at the temperature 80 to 180 °C run in the last one or in the last reaction stages of oxidation reactor not feed with gas containing oxygen and/or in a separate reactor or reactors of cyclohexyl hydroperoxide decomposition, at the presence of catalyst being solution of salt of metal of the variable valence in cyclohexane characterized in that there is used a catalyst previously diluted, directly before introduction to the reaction system, in oxygen free conditions with pure cyclohexane, not containing the products of its oxidation, from 25 to 1000 times, preferably from 50 to 200 times, from a concentrate having concentration from 0.1 to 2.5 % of metal in cyclohexane solution, that is up to the concentration from 0.0001 to 0.1 %, preferably from 0.0005 to 0.05 %, at the temperature from 10 to 150 °C, preferably from 20 to 100 °C, while before introduction into the separate reactor or reactors of cyclohexyl hydroperoxide decomposition the diluted catalyst is intensively mixed with the stream of oxidate leaving the oxidation reactor and introduce into those reactors.
Unexpectedly it was found out that it was possible to achieve considerable
improvement of selectivity of the cyclohexane oxidation process as well as cyclohexyl
hydroperoxide decomposition even without change of the applied catalysts type, and
especially using too expensive catalysts and while using solutions of simplicity
corresponding to the industrial use requirements and while keeping the above
mentioned basic process solutions characteristic for the "Cyclopol" process as well as
the basic geometric and construction solutions of the oxidation reactor according to
the above mentioned Polish patents, that is without significant investment costs in the
installations working according to this process. The method according to the invention
also makes possible reduction of catalysts consumption due to reduction of the
phenomenon of their deactivation as well as reduction to higher
and lower degree the phenomenon of forming and deposition of
sediments in the apparatus, always occurring in the process of oxidation.
According to the invention the method for selective oxidation of cyclohexane to cyclohexanol, cyclohexanone and cyclohexyl hydroperoxide consists in the fact that there is used a catalyst previously diluted directly before introducing into the reaction system, in oxygen-free conditions, by means of pure cyclohexane not containing products of its oxidation, and not by so called circulating cyclohexane distilled from the reaction products. There is used a catalyst diluted from 25 to 1000 times, preferably from 50 to 200 times, from the concentrate of the concentration from 0.1 to 2.5% of metal in cyclohexane solution, that is up to the concentration from 0.0001 to 0.1%, preferably from 0.0005 to 0.05%, at temperature lower from the temperature of the cyclohexane oxidation reaction, that is from 10 to 150°C, preferably from 20 to 100°C in the conditions of intensive mixing. Directly after the operation of dilution the diluted catalyst is introduced into each or the majority of the reaction stages in several points in every reaction stage with pipe distribution elements in 2 up to 100, preferably in 3 up to 10, points of introduction in order to keep appropriate concentration of the catalyst active form
in the reaction fluid. The catalyst is introduced into the reaction stages, most preferably into the zone of gassing with oxidizing gas containing oxygen (for instance with air or air enriched with oxygen) into circulating cells of oxidized fluid in countercurrent to the direction of oxidizing gas bubbles lifting, with the velocity allowing to achieve intensively turbulent flow in the outflow of the distributing elements of catalyst solution and intensive mixing of this solution with the reaction fluid, that is with linear velocity of outflow of distributing elements pipe ends from 0.01 up to 0.5 m/s, preferably from 0.1 up to 0.2 m/s.
Catalyst dilution is performed in a flow mixer in which the catalyst concentrate is introduced radially into a ring-shaped stream of flowing cyclohexane coaxially surrounding its feed, perpendicular to the direction of its flow, and both mixed components are set into rotational motion in a swirl element. There are used catalysts being salts consisting of metal of variable valence chosen among: cobalt, manganese, iron, chromium, molybdenum, and acid radical chosen among: alkyl carboxylic, naphthenic, alkyl phosphoric, alkyl sulfonic and aryl sulfonic acids. Also according to the invention the method for selective decomposition of cyclohexyl hydroperoxide
in cyclohexane oxidate to cyclohexanol and cyclohexanone consists in the fact that there is used a catalyst previously diluted directly before introduction into the reaction system, in oxygen-free conditions with pure cyclohexane not containing products of oxidation from 25 to 1000 times, preferably from 50 to 200 times, from the concentrate of the concentration from 0.1 to 2.5% of metal in cyclohexane solution, that is up to the concentration from 0.0001 to 0.1%, preferably from 0.0005 to 0.05%, at the temperature from 10 to 150°C, preferably from 20 to 100°C. This diluted catalyst is introduced into the reaction stages of the oxidation reactor not fed with oxidizing gas containing oxygen and/or to a separate reactor or reactors of cyclohexyl hydroperoxide decomposition. Introduction to the reaction stages of the oxidation reactor proceeds with intensive mixing of liquid phase contained in it in order to provide turbulence favourable for good mixing of the catalyst in the reaction volume, in several points in every reaction stage with pipe distribution elements in 2 up to 100, preferably in 3 up to 10 points of introduction, with linear velocity of catalyst solution outflow from the distribution elements pipe ends from 0.01 to 0.5 m/s, preferably
from 0.1 to 0.2 m/s. Turbulence can be achieved by known methods, for instance by means of mechanical mixers, external circulation pumps, jet pump systems or pneumatic mixing. While before introduction into a separate reactor or reactors of cyclohexyl hydroperoxide decomposition the diluted catalyst is joint and mixed intensively with the stream of oxidate leaving the oxidation reactor and it is introduced into these reactors preferably through a swirling element.
Catalyst dilution is performed in a flow mixer in which the catalyst concentrate is introduced radially into a ring stream of flowing cyclohexane coaxially surrounding its inflow, perpendicular to the direction of its flow, and both mixed components are set into rotational motion on the swirling element. Joining and mixing the diluted catalyst with oxidate is performed in a flow mixer in which the diluted catalyst is introduced into a swirled stream of oxidate, and the mixture of both components is turbulized on turbulizing blades. There are used catalysts being salts consisting of a metal of variable valence chosen among: cobalt, manganese, iron, chromium, molybdenum, and an acid radical chosen among: alkyl carboxylic, naphthenic, alkyl phosphoric, alkyl sulfonic and aryl sulfonic acids.The equipment for cyclohexane oxidation according to the invention is specific by the fact that a flow mixer for catalyst diluting consisting of catalyst concentrate pipe inflow, the end of which provided with outflow holes of the concentrate is coaxially introduced into pipe inflow of cyclohexane of larger diameter provided with a swirl plate at its outflow, joined to the pipe distribution elements of the catalyst solution, which in the sections fed with oxygen containing oxidizing gas have from 2 to 100, preferably from 3 to 10, catalyst outflow ends.
The equipment for cyclohexyl hydroperoxide decomposition also according to the invention includes a flow mixer for catalyst diluting consisting of catalyst concentrate pipe inflow, the end of which provided with concentrate outflow holes is introduced coaxially into cyclohexane pipe inflow of larger diameter provided at its outflow with a swirl plate, connected to the catalyst solution distributing elements, which in sections not-fed with oxygen containing oxidizing gas, have from 2 to 100, preferable from 3 to 10, catalyst outflow ends. The equipment also contains flow mixer of catalyst introduction into cyclohexane oxidate directed from the oxidation reactor to a separate reactor or reactors
of cyclohexyl hydroperoxide decomposition consisting of a pipe section of this oxidate conduit, which is provided at its inflow with a set of swirling blades, while at its outflow with a set of turbulence blades and introduced into it at the rightangle between these sets of blades, pipe section of a conduit of smaller diameter holes for catalyst outflow drilled on it. While at the inflow of the oxidate mixture with the catalyst to a separate reactor or reactors of cyclohexyl hydroperoxide decomposition the equipment has a swirling element being of section of the conduit consisting of a narrowing inflow part, increasing flow velocity, and a spreading outflow part, in which there is located a head of the streamlined shape, reducing flow resistance, and swirling blades.
Confirmation of the solution efficiency was searched by exposing to deep analysis the reaction of cyclohexane oxidation from the point of view of its mechanism, macrokinetic model, dynamic phenomenon (first of all mixing) as well as properties and behaviour of the catalysts, performing several experiments and tests, as well.
The starting point for the considerations it was the Polish process, Cyclopol".
The first doubts concerning correctness of the solution used up to now appeared due to examination of circulation cells in the industrial reactor by a radiomarker method while using isotope La-140 of high energy of emitted gamma quantum. The isotope was located in a wooden ball and introduced into the reactor. The measurements in the operating conditions of the reactor (temperature 160°C, pressure 9 bars) allowed to localize the fluid circulation cells and to specify the gas zone and the zone of fluid falling in this cells. This research allowed to specify the fluid circulation velocity in the reactor, one of more important parameters indispensable for reactor work simulation calculation. Further research concerned intensity of mixing in several sections of the reactor. The measurements were also performed by a radio marker method using isotope Br-82 introduced into the reactor in the liquid form with cyclopean. The experiments showed that there is no excellent mixing in the direction perpendicular to the direction of fluid flow. There were observed fluid stagnation areas and the volume share of these stagnation zones, depending upon the reaction section, remained within the range 11 to 37% (on the average 20%).
The above mentioned experiments also showed unexpectedly some contradiction occurring for one section of the reactor in its solution according to the Polish patents 64449 and 152429. It consists in the fact that application of additional circulation buffle located crosswise to the direction of post reaction mixture flow through the reactor (according to the patent 152429) reduces reverse mixing within the range of one reaction stage, due to which it increases favorable in such reactions (and realized according to the patent 64449) multistage effect of reaction running (allowing for approaching to the piston type reactor), however, from the point of view of catalyst introduction there appears a new problem consisting in difficult in this conditions quick and uniform spreading of the catalyst in the section.
Examination of behavior of catalyst, especially cobalt and chromium naphthenate, confirmed the observations concerning the phenomenon of deactivation of the cyclopean oxidation catalyst. In detailed experiments it was found out that activity time of cobalt and chromium catalyst in the cyclopean oxidation reaction conditions was very short, equal to a few minutes, while in the conditions of WNCH decomposition reaction run without
aeration, the time of the cobalt catalyst life remains on the same level, while the time of the chromium catalyst activity elongated slightly. It was also observed that it was very noxious for the catalysts to have water present (in lower degree but also organic acids C1-C4 present) and that agglomerated deactivated catalysts are an important deposit-forming factor.
The reasons for such behaviour of the catalyst were explained among others by performing during the experiments described below in examples 1 to 5 an analysis of cobalt remaining in the solution after 10 minutes of oxidation reaction depending upon the degree of dilution in which it was supplied to the reaction, and in examples 6 and 7 - similar analysis of hromium content.
Example 1 - 7There was used laboratory equipment of the volume 1dm3 consisting of a reactor (made by Parr) with a paddle mixer, a reflux condenser connected to a phase separator, device for gas dosing, devices for catalyst dosing (adapted pump for preparative liquid chromatograph made by Shimadzu) and a cooler for samples taking. The analysis of oxidation products
included chromatographic analysis (in two capillary columns SPB-1 and Supelcovax) of liquid samples allowing for determination of cyclohexanone, cyclohexanol and cyclohexyl hydroperoxide as well as 165 volatile products up to cyclohexyl adipinate including with the accuracy up to 10-5 mole/dm3 (majority of the products were identified by means of mass spectrometry, for the rest molecular weight was determined). Additionally titrimetric analysis through analysis of acid number and comparing with chromatographic determination allowed for determination of dicarboxylic acids and formic acid with accuracy for this acids sum 10-4mole/dm3. In total with analysis of gas products (carbon dioxide and carbon oxide) determinated concentrations allowed to calculate selectivity of cyclohexane conversion for each sample taken during the test.
In the atmosphere of nitrogen the reactor was filled with 600 cm3 of cyclohexane and heated to the temperature of 158°C. The reaction of oxidation was started by dosing air in the quantity 2.5 dm3/min. (calculated for normal conditions) and the catalyst in the form of solution of 2-ethylcapronate salt of transition metal of the concentration given in Tables 1-2 prepared directly before use by diluting with pure
cyclohexane the concentrate containing 0.5% of metal. This solution was dosed continuously at the velocity allowing to obtain after 10 minutes the estimated quantity of introduced metal (column 3 in Tables 1-2), which was equal to 18 microliters/min up to 18 mililiters/min. At the same time there was kept a constant level of fluid in the reactor by additional refilling of evaporated cyclohexane with pure cyclohexane. The sample for metal analysis were taken after 10 minutes of reaction through a filter of 0.5 micrometers and after weighing they were mineralized. Conversion was calculated on the basis of carbon balance as a quotient of moles sum of carbon contained in determined oxidation products to the quantity of carbon moles contained in cyclohexane. The selectivity was calculated as a quotient of the determined sum of moles quantity of carbon contained in cyclohexanol, cyclohexane and cyclohexyl hydroperoxide to the sum of moles quantity of carbon contained in all determined products.
Table 1(Table Removed)Table 2. (Table Removed)
The results of the cobalt analyses of Examples 1 and 2 were plotted on the diagram of catalyst concentration simulated for the deactivation reaction of the first and second order towards cobalt, presented on the diagram of Figure no.1. On the diagram there was presented concentration of theSelectivity to the sum of cyclohexanol, cyclohexanone and cyclohexyl hydroperoxide % by mole
catalyst dissolved near the place of dosing in time
function. The denotation on the diagram is as follows:
-time units - relative (on the axis X),
-concentration expressed in a mole fraction
metal/cyclohexane (on the axis Y),
-broken line - deactivation according to the first order
reactions,
-full line - deactivation according to the second order
reactions,
-line with a single dot - concentration of solved
catalyst from Example No.6,
-line with a double dot - concentration of the solved
catalyst from Example 7,
In a logarithmic scale of this diagram the changes proceeding according to first degree kinetics are presented by straight lines, while the second degree kinetics of vanishing of the catalyst active form is non-linear in this scale. Only non-linear kinetics of the catalyst deactivation can explain final concentration of the catalyst observed in the examples. In the result of the catalyst deactivation there were achieved 0.015 ppm of cobalt remaining after the reaction in solution in Example 1, while 0.021 ppm in Example 2, in spite of introduction of houndred-times larger quantity of cobalt (the
determined concentrations are lower than the limiting ones mentioned in the above cited American patent no.4326084 due to the development of analytical methods). This means that deactivation of the catalyst proceeding during dosing and the reaction at the presence of oxygen is a reaction of the degree higher than one in relation to the catalyst, or that in catalyst deactivation oxidizers present in the environment participate. This unexpectedly indicates a possibility of higher losses of the catalyst supplied in more concentrated solution. On the diagram the lines of simulated concentrations indicate that after some sufficient dilution of the catalyst, it is actually possible to elimiminate deactivation; for instalce on the diagram it is hundred-times dilution with deactivation according to the second degree. The experimental data of the above examples 3-7 confirm that together with increase of dilution of the catalyst supplied in the same quantity, the selectivity of cyclohexane oxidation increases.
Similar experiments were performed in the view of the process of cyclohexyl hydroperoxide decomposition. Their results were included into Examples 8-13. They indicate that selectivity of
NCH decomposition increases together with increase of supplied catalyst dilution. Example 8-13
There was used laboratorty equipment described in Examples 1-7. Analysis of oxidation products included chromatographic analysis of liquid samples in a capillary Column SPB1, allowing determination of cyclohexanone, cyclohexanol and cyclohexyl hydroperoxide with the accuracy up to 10-5 mole/dm3. The determined concentrations allowed to calculate selectivity of WNCH conversion to cyclohexanol and cyclohexanone for each sample taken during the experiment.
The reactor was pssivated with 3% water solution of sodium pyrophosphate at the temperature of 100°C. In the atmosphere of nitrogen the reactor was filled with 600 cm3 of cyclohexane and heated to the temperature 158°C. The reaction of oxidation was started by dosing air in the quantity 2.5 dm3/min (in normal conditions). During oxidation there was observed composition of products by taking samples of liquid from the reactor and analysing concentration of the sum of cyclohexanol and cyclohexanone as well as WNCH by quick chromatographic analysis. The moment WNCH concentration in the taken sample

exceeded 1% by weight, with the delay of 3 minutes necessary for analysis, air dosing was stopped, the rector system was washed with 10 dm3 of nitrogen and there was dosed catalyst solution in the form of solution of cobaltous 2-ethylcapronate or chromium (III) naphenate of the concentrations given in Tables 3-4. The solution was dosed in such a way so as to obtain the concentration of 0.5 ppm of metal in the reaction mixture, which lasted for 20 seconds. Because the quantities of introduced catalyst solution were different, there was additionally introduced into the reactor through the second hole some quantity of cyclohexane, so as the summary quantity of introduced cyclohexane was always 10 cm3. Stable temperature of the reactor equal to 158°C was kept. The first sample for analysis was taken before introduction of the catalyst, the next ones every 2.5 min. The selectivity of WNCH decomposition was calculated as a quotient of the sum of moles quantity of cyclohexanol and cyclohexanone formed in several time sections between samples taking and the quantity of WNCH decomposed with this time. There was calculated constant of WNCH decomposition in the first order reaction for the initial stage up to 2.5 min. of the reaction and for the final stage after 5 min.of the reaction when the catalyst was already partially deactivated.
Table 3. (Table Removed)Comparison of Examples 8-10 and 11-13 shows that suppling the catalyst of active component lower concentration improves velocity of the WNCH decomposition reaction as well as selectivity of decomposition. Observed differences of calculated constants of velocity of pseudo-first-order WNCH decomposition reaction for the initial and final stage of this reaction indicate smaller deactivation of catalysts introduced into the reactor in lower concentration. Lower selectivities observed for WNCH decomposition towards chromium catalyst are connected with other mechanism of this catalyst activity. The cobalt catalyst decomposes WNCH with oxygen evolving, which causes observed selectivity higher than 100%, caused by oxidation of additional cyclohexane quantity; chromium catalyst decomposes WNCH with water evolving. Howver, it is necessary to stress that this additional cyclohexane oxidation proceeds with considerably lower selectivity, which in the effect can bring to lower entire selectivity of the cyclohexane oxidation process.
In other considerations expected to confirm correctness of the solutions according to the invention there were taken into consideration macrokinetic research as well as generating of mathematical model
of the process considering mixing models
(A.Krzysztoforski, Z.Wojcik, R.Pohorecki, J.Batdyga, I&EC Process Design & Development, 25, 894-896, 1986; R.Pohorecki, J.Baldyga, W.Moniuk, A.Krzysztoforski, Z.Wojcik, Chem.Eng. Sci., 47, 2559-2564, 1992; J.Bakiyga, R.Pohorecki, Chem.Eng.J., 58, 183-195, 1995).
As it is known, oxidation of cyclohexane in liquid phase proceeds according to a radical, chain mechanism with degenerate branches. The kinetic diagram corresponds to the system of series-simultaneous reactions. For the process of non-catalytic oxidation, Charkowa and others (T.W.Charkowa, I.L.Arest-Jakubowicz, W.W.Lipies, Kinetika i Kataliz, 30, no.4, 954-958, 1989) present 19 simple reactions being elements of the kinetic diagram. Using the information given by Charkowa and others and basing on our own macrokinetic research, there was elaborated a new kinetic diagram of the cyclohexane oxidation catalytic process considering the stages of forming and decomposition of cyclohexyl hydroperoxide. In further simulation works there was used the kinetic diagram of cyclohexane oxidation presented on Fig.2.
Analising the problem of mixing of the catalyst solution with the reaction mixture, there was considered that mixing of two solutions at the molecular scale proceeds according to the sequence: macromixing, mesomixing and micromixing.
Macromixing consists in mixing of both fluids in macro scale (that is in the scale near to the reactor scale, and rather one of its sections). The process of macromixing is strongly connected with the method and place of substrates supplying and it concerns those large scale flows, which cause realization of distribution of large scale values parameteres such as distribution of average catalyst concentration in the reactor or distribution of residence time of fluid containing the catalyst in the reactor.
Mesomixing consists in turbulent dispersion of large fluid elements (for instance in this case containing fresh catalyst) in the reaction mixture. The elements of fluid have dimensions similar to the diameter of element introducing fluid (in this case of the diameter of the pipe through which in one point the catalyst is introduced). The second aspect of the mesomixing process consists in inertial-convective reduction of those fluid elements size. Mesomixing
determinates structures of environment for the process of micromixing.
Micromixing - the last stage of turbulent mixing - consists in viscous-convective deformation of fluid elements, which is followed by molecular diffusion. An important feature of micromixing is acceleration of molecular diffusion through a process of viscous-convective deformation. This happans because competition beteen micromixing and chemical reaction determines influence of mixing on the chemical reaction or on sediment precipitation. Non-homogeneity connected with occuring of imperfect meso- and micromixing has indirect, although often very strong, influence on the chemical reaction.
Using mathematical model of the process based on macrokinetic basis and on the above presented principles of turbulent mixing, there was performed simulation of influence of preliminary catalyst dilution with fresh cyclohexane in the industrial reactor work conditions, providing ideal piston flow in the direction of fluid flow. In several simulation calculations there were asumed the same quantities of the catalyst supplied in solutions of various dilution degrees.
Below in Table 5-9 there were presented results of numerical simulation of the process course.
There were presented results of simulation
calculations relating to a nominal option, that is for
«
the hitherto method of catalyst introduction, it means without diluting and in one point. In all the examples the ratio of flow of gas and fluid is the same.
In the description of the examples there were given the following ratios:
- conversion a / a „, selectivity  n ααn/αn n
efficiency (expressed as a product of conversion and
selectivity ααn n.
The index n stands for a nominal option. Table 5 concerns the case in which there is supplied catalyst ten times more concentrated in relation to the nominal option.
There were considered one-point or four-points variants of catalyst dosing to the reactor section.
Table 5
Feeding with the catalyst of the concentration 10-times larger than the nominal one, one point supply of the catalyst.
α/αn  n ααn/αn n
1-order kinetics of
catalyst deactivation 0.993 0.965 0.959
2-orders kinetics of
catalyst deactivation 0.992 0.965 0.958
Table 6.
Feeding with the catalyst of the concentration 10-times smaller than the nominal one, one point supply of the catalyst.
α /αn  n ααn/αn n
1-order kinetics of
catalyst deactivation 1.001 1.034 1.035
2-orders kinetics of
catalyst deactivation 1.047 1.037 1.086
Table 7
Feeding with the catalyst of the concentration 100-times lower than the nominal one, one point supply of the catalyst.
α/αn  n ααn/αn n
1-oder kinetics of
catalyst deactivation 1.002 1.064 1.066
2-oreders kinetics of
catalyst deactivation 1.052 1,068 1.124
Table 8
Feeding with the catalyst of the concentration 10-times lower than the nominal one, four-points supply of the catalyst.
one-order kinetics of
catalyst deactivation 1.003 1.039 1.042
2-orders kinetics of
catalyst deactivation 1.049 1.040 1.091
Table 9
Feeding with the catalyst of the concentration 100-time lower than the nominal one, four-points supply of the catalyst,
α/αn  n ααn/αn n
1-order kinetics of
catalyst deactivation 1.008 1.065 1.074
2-orders kinetics of
catalyst deactivation 1.054 1.077 1.135
In the following table 10 and 11 there was illustrated influence of dilution degree of the cyclohexyl hydroperoxide decomposition catalyst on selectivity of decomposition. In calculations there was used the same kinetic diagram. In several calculations there were asumed the same quantities of the catalyst supplied in solutions of various dilution degrees. Taking into consideration the above presented influence of multipoints catalyst introduction, the calculations were performed only for the variant of one-point dosing.
In the below tables a stands for the degree of
cyclohexyl hydroperoxide decomposition, while
for selectivity of cyclohexyl hydroperoxide decomposition. Analogically as in Tables 5-9 the index n stands for the nominal option.
Table 10
Feeding with the catalyst of the concentration 10-
times lower than the nominal one.
α/αn  n ααn/αn n
1 -order kinetics of
catalyst deactivation 1.006 1.012 1.018
2-orders kinetics of
catalyst deactivation 1.013 1.050 1.064
Table 11
Feeding with the catalyst of the concentration 100-
times lower than the nominal one.
α/αn  n ααn/αn n
1-order kinetics of
catalyst deactivation 1.007 1.049 1.056
2-orders kinetics of
catalyst deactivation 1.016 1.079 1.096
As it can be seen from the above tables, there is definite dependence of selectivity upon the degree of dilution and the way of the catalyst introduction. In Table 9, referring to 100-times dilution of the catalyst and its introduction in four points, there is obtained selectivity of 6-8% of (relative) higher than the nominal option.
The above results confirmed that it is favourable to supply catalyst in the strongly diluted form and to introduce it in numerous points in possibly large area of the reactor so as to avoid its high local concentrations. The above results also determined to increase the hitherto kinetic research, which brought to the following further conclusions confirming correctness of the solutions according to the invention:
Deactivation of the catalyst is connected with its precipitation in the form of sediment, which is possible among others due to high catalyst concentration, high concentration of oxygen and radicals containg chemically bound oxygen. Therefore, there is an essential difference between
dilution of the catalyst before its introduction to the reactor and dilution with the reaction mixture in the very reactor. Unexpecteddly it was found out that catalyst dilution should be run with fresh cyclohexane containing neither oxidizers nor water nor organic acids. As it results from the presented kinetic diagram, the main reaction causing catalyst deactivation is the reaction of order higher than one in relation to the catalyst, in which there participate oxygen or the process products of the oxidizers type. Therefore, dilution of the catalyst and its storage in pure conditions (pure solvent) protects it from deactivation. While dilution of the catalyst in working conditions of oxidizing reactor or with cyclohexane containing oxidation products is not favourable and it causes deactivation.
The equipment for cyclohexane oxidation according to the invention have been shown on a figure, on which Fig.3 presents in a diagrammic view, Fig.4 presents a mixer for catalyst dilution and Fig.5 illustrates a catalyst distribution system in the oxidation reactor. The equipment consists of a six-sections oxidation reactor 1 and a flow mixer 2 for catalyst concentrate dilution with cyclohexane. The
mixer 2 consists of two coaxial pipes 3. and 4 and a swirl plate 5. The pipe 3 of smaller diameter, introduced coaxilly into the pipe 4of lager diameter, being supply of the catalyst concentrate has outflow holes 6. The pipe 4 of larger diameter being supply of diluting cyclohexane has near to the end of the pipe 3, but before introduction of the mixture, a swirl plate 5. The mixer 2 is joined with its outflow conduit to pipe distributing elements 7 to the catalyst solution. In each section of the oxidation reactor the distribution element 7 has three outflow ends 8 of the catalyst solution located in the sections spaces divided with baffle piers 9.
The equipment for cyclohexyl hydroperoxide decomposition according to the invention has been shown on the example presented on a figure, on which Fig.6 presents it on a diagrammatic view, Fig. 7 presents a mixer for catalyst dilution to cyclohexane oxidate, Fig.8 - its section with A-A plane, Fig.9 - its section with B-B plane, Fig.10 presents a swirl element, while Fig 11 a section of this element with C-C plane. The equipment consists of two joined in series apparatus 10 and 11 being empty flow vessels. The equipment is provided with a separate flow mixer for catalyst dilution presented on Fig.4. This separate
mixer connected to a conduit 12 of the diluted catalyst with two mixers 13. and 14 for introducing and mixing the diluted catalyst of decomposition of WNCH with cyclohexane oxidate leaving the oxidation reactor. The mixers 13 and 14 are located correspondingly at the inflows into the apparatus 10. and 11. To the mixers 13 and 14 there is supplied a cyclohexane oxidate conduit. The mixer 13 or 14 consists of two sections 15 and 16 of the pipe conduit joined with each other at the right angle. The section 15 of the large diameter is a part of the conduit supplying cyclohexane oxidate to the apparatus of WNCH decomposition. In the section 15 there are located two sets of blades, the swirling blades 17 located at the inflow to the mixer and the turbulizing blades 18 located at its outflow. The section 16 of small diameter is an end of the conduit supplying diluted catalyst, introduced into the section 15 at the right angle, between those sets of blades. It has outflow holes 19 for the diluted catalyst drilled in its walls. At the inflow to the apparatus 10 and 11 there are located swirling elements 20. and 21. the inflows of which are connected to the outflows of the mixers 13 and 14 The swirling element 20 or 21 is a section of the conduit, an inflow part 22. of which narrowing
towards the direction of the oxidate mixture flow with the catalyst is for increase of velocity of the reaction mixture flow, and the outflow part 23. spreading towards the same direction is for setting the mixture into rotational motion. In the outflow part 23 there is located a head 24 of the streamline shape used for reduction of resistance of flow and swirling blades 25.



We claim:
1. Method for cyclohexanol, cyclohexanone production by selective oxidation of cyclohexane to cyclohexanol, cyclohexanone and cyclohexyl hydroperoxide in liquid phase with gases containing oxygen, at the temperature 140 to 180 °C in a reaction flow system consisting of more than one reaction stage, containing circulation cells of the liquid phase as herein described, at the presence of catalyst being solution of salt of metal of the variable valence in cyclohexane, introduced into each or into the majority of reaction stages and next selective decomposition of cyclohexyl hydroperoxide in liquid phase at the temperature 80 to 180 °C run in the last one or in the last reaction stages of oxidation reactor not feed with gas containing oxygen and/or in a separate reactor or reactors of cyclohexyl hydroperoxide decomposition, at the presence of catalyst being solution of salt of metal of the variable valence in cyclohexane characterized in that there is used a catalyst previously diluted, directly before introduction to the reaction system, in oxygen free conditions with pure cyclohexane, not containing the products of its oxidation, from 25 to 1000 times, preferably from 50 to 200 times, from a concentrate having concentration from 0.1 to 2.5 % of metal in cyclohexane solution, that is up to the concentration from 0.0001 to 0.1 %, preferably from 0.0005 to 0.05 %, at the temperature from 10 to 150 °C, preferably from 20 to 100 °C, while before introduction into the separate reactor or reactors of cyclohexyl hydroperoxide decomposition the diluted catalyst is intensively mixed with the stream of oxidate leaving the oxidation reactor and introduce into those reactors.
2. The method as claimed in claim 1 wherein the diluted catalyst is introduced into the
reaction stages at intensive mixing of liquid phase in several points through pipe
distribution elements and the number of points of introduction to each section is from 2 to
200, preferably from 3 to 10.
3. The method as claimed in claim 1 wherein the diluted catalyst is introduced into the
reaction stage gassed with oxidizing gas containing oxygen, into the liquid circulation cells
in counter current to the direction of gas bubbles going up.
4. The method as claimed in claim 1 wherein the diluted catalyst is introduced with the
linear velocity at the outflow from the pipe distribution elements from 0.01 to 0.5 m/s

preferably from 0.1 to 0.2 m/s.
5 The method as claimed in claim 1 wherein the mixture of the diluted catalyst with the oxidate is introduced into the separate reactor or reactors of cyclohexyl hydroperoxide decomposition through a swirling element.
6. The method as claimed in claim 1 wherein the diluted catalyst is joined and intensively
mixed with cyclohexane oxidate in a flow mixer in which the diluted catalyst is introduced
into a swirled oxidate stream and the mixture of both components is turbulize on
turbulizing blades.
7. The method as claimed in claim 1 wherein the catalyst dilution is run in a flow mixer
into which the catalyst concentrate is introduced radially into surrounding it coaxially a
ring stream of flowing cyclohexane perpendicularly to the direction of its flow and both
mixed components are set into rotational motion on a swirling element.
8. The method as claimed in claim 1 wherein there are used catalysts being solution of
salts consisting of a metal with variable valence chosen among cobalt, manganese, iron,
chromium, molybdenum and acid radical chosen among alkyl carboxylic, napthenic, alkyl
phosphoric, alkyl sulfonic and aryl sulfonic acids.
9. Apparatus for producing cyclohexanone and cyclohexanol, by the method as claimed in
claim 1, being a horizontal flow- through multi sectional reactor of cyclohexane oxidation
equipped with distribution elements of catalyst solution and this reactor and vessel type
reactor or reactors of cyclohexyl hydroperoxide decomposition, characterized in that it
contains the flow mixer (2) of catalyst dillution consisting of a pipe inflow element (3) of the
catalyst concentrate, the end of which having concentrate outflow holes (6) is introduced
coaxially into a pipe inlet (4) of cyclohexane having bigger diameter, equipped at its outflow
with a swirl plate (5) joined to pipe distribution elements (7) of catalyst solution, having
from 2 to 200, preferably from 3 to 10, catalyst outflow ends (8) and mixer (13) or mixers
(13) and (14) for feeding catalyst to cyclohexane oxidate directed from oxidation reactor to
separate reactor (10) or reactors (10) and (11) of cyclohexyl hydro peroxide decomposition,
consisting of pipe element (15) of these oxidate equipped at its inflow with a set of swirling
blades (17) and at its outlet with a set of turbulising blades (18) and introduced into it
perpendicularly between the sets of these blades pipe inlet (16) with drilled holes (19) of
catalyst outlet, while at the inlet of the mixture the oxidate and the catalyst into the
separate reactor or reactors of cyclohexyl hydroperoxide decomposition the equipment has

a swirling element (20) or swirling elements (20) and (21) being a part of pipe consisting of a narrowing inlet part (22 increasing the outflow velocity and with a spreading outlet part (23) in which there is located a head (24) of streamline shape reducing the flow resistance, and swirling blades (25).

Documents:

108-del-1997-abstract.pdf

108-del-1997-claims.pdf

108-DEL-1997-Correspondence Others-(22-03-2011).pdf

108-del-1997-correspondence-others.pdf

108-del-1997-correspondence-po.pdf

108-del-1997-description (complete).pdf

108-del-1997-drawings.pdf

108-del-1997-form-1.pdf

108-del-1997-form-13.pdf

108-del-1997-form-19.pdf

108-del-1997-form-2.pdf

108-DEL-1997-Form-27-(22-03-2011).pdf

108-del-1997-form-3.pdf

108-del-1997-form-4.pdf

108-del-1997-gpa.pdf

108-del-1997-petition-137.pdf

108-del-1997-petition-138.pdf

108-del-1997-petition-others.pdf


Patent Number 214796
Indian Patent Application Number 108/DEL/1997
PG Journal Number 09/2008
Publication Date 29-Feb-2008
Grant Date 15-Feb-2008
Date of Filing 14-Jan-1997
Name of Patentee ZAKLADY AZOTOWE W TARNOWIE-MASCIACH, SPOLKA AXCYJINA UL.
Applicant Address KWIATKOWSKIEGO 8, 33-101 TARNOW, POLAND
Inventors:
# Inventor's Name Inventor's Address
1 LEON WIESLAW ZATORSKI 05-800 PRUSZKOW UL. CHOPINA 2/4 M. 28, POLAND;
2 MAREK ZYLINSKI, 33-101 TARNOW, UL. BRONIEWSKIEGO 5.POLAND;
3 ANDRZEJ KRZYTOFORSKI 33-100 TARNOW, UL. TOWAROWA 5, POLAND
4 WITOLD MIJAL 33-100 TARNOW, POWSTANCOW WARSZAWY 6/45, POLAND;
5 ZBIGNIEW TUMILOWICZ 33-100 TARNOW, UL. POWSTANCOW WARSZAWY 6/8, POLAND;
6 MARIAN PACIOREK 33-101 TARNOW, UL. CZARNA DROGA 39, POLAND;
7 STANISLAW OCZKOWICZ 33-100 TARNOW, UL. SKOWRONKOW 6/30, POLAND
8 JAN MACZUGA 33-100 TARNOW, UL. KIEPURY 24, POLAND
9 JAN REDZI 33-100 TARNOW, UL. REYMONTA 29/41, POLAND;
10 ZBIGNIEW WOJCIK 33-100 TARNOW, UL. BITWY POD STUDZIANKAMI 1/7, POLAND;
11 ANTONI JANUSZ GUCWA 33-100 TARNOW, UL. ROLNICZA 5A/14, POLAND
12 RYSZARD POHORECKI 02-922 WARSZAWA. UL., NALECZOWSKA 47/68, POLAND;
13 WLADYSLAW MONIUK 02-904 WARSZAWA, BERNARDYNSKA 5/11, POLAND
14 PIOTR WIERZCHOWSKI, 04-743 WARSZAWA, UL CZELADNICZA 6A, POLAND
15 JERZY ROBERT BALDYGA 05-400 OTWOCK, KARCZEWSKA 57/52 POLAND;
16 STANISLAW RYGIEL 33-100 TARNOW, UL.REYMONTA 31, POLAND;
17 JAN WAIS 33-100 TARNOW,UL. ROLNICZA 5A, POLAND
PCT International Classification Number C07C 27/14
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA