Title of Invention

A PROCESS FOR THE PREPARATION OF NOVEL CATALYST USEFUL FOR DEHYDROGENATION REACTION

Abstract

The present invention provides to a process for the preparation of novel catalyst useful for dehydrogenation reactions. More particularly this invention provides the development of highly active and selective catalysts consisting of combinations of metals or their salts from group.VIII (Fe, Co, Ni families) and group IB (Cu, Ag, Au) along with promoters and initiators such as metals and salts of group VI and vllB like Cr, Mo, W, Mn, Tc and Re which are suitably used in the media either as such or in combination with alkali and alkaline metal salts and in varied phase transfer solvent media, supported upon inert, basic or acidic supports like alumina, silicagel, ceramic, kieselguhr, Bentonite, Askansk clay, Askonite etc. under optimum conditions of temperature and time.

Full Text

The present invention related to a process for the preparation of novel catalyst useful for dehydrogenation reactions. The invention particularly relates to a process for the production of new supported metal atom dispersed catalyst for the oxidation of cyclic ketones into corresponding phenols and related compounds. More particularl this invention relates to the development of highly active and selective catalysts consisting of combinations of metals or their salts from group VIII (Fe, Co, Ni families) and group IB (Cu, Ag, Au) along with promoters and initiators such as metals and salts of group VI and VIIB like Cr, Mo, W, Mn, Tc and Re which are suitably used in the media either as such or in combination with alkali and alkaline metal salts and in varied phase transfer solvent media supported upon inert, basic or acidic supports like alumina, silicagel, ceramic, kieselguhr, Bentonite, Askansk clay, Askonite etc. under optimum conditions of temperature, pressure, pH and time. Numerous terpene ketones like menthone, isomenthone, piperitone, piperitenone and pulegone etc. are available as low cost industrial bye products and finds little use as such, but can be utilized as raw materials for the production of other useful chemicals like thymol. In such cases, the oils and bye product containing these chemicals can be rectified by distillation to obtain concentrates of individual terpenes such as menthone-isomenthone, piperitone and pulegone. Menthone, C10H20O , M+ 156.25, bp. 207° C, d25 0.895 and isomenthone, C10H20O, M+ 156.25, bp. 210° C, d25 0.896; occur naturally in various essential oils, particularly of Mentha species. In inventing the present process, the advantage has been taken of the fact that in recent years, India has emerged as a major producer of Mentha arvensis oil (15,000-20,000 tones/year) containing 15-20% of menthone-isomenthone in addition to menthol (70-80%) and other compounds. After separation of menthol by crystallization, the dementholised oil rich in menthone/ isomenthone is available in large amounts as a low cost industrial bye product, from which menthone -isomenthone (2200-3000 tones/annum) can be separated for the production of other useful chemicals. The additional quantities of menthone-isomenthone are also available world over. Small amount of menthone and dementholised oil is used as such in flavour industry. In such cases dementholised oils are usually rectified by distillation to obtain concentrates of individual terpenes or group of terpenes such as terpene hydrocarbons, menthone-isomenthone mixture, menthol isomers and high boilers. Catalytic dehydrogenation of terpene ketones in liquid phase has been attempted by several workers by using sulphur, selenium dioxide, ferric chloride, halogens, copper, nickel, noble metals and other catalysts [RRL, News Lett. (1989), 16(2) 8; Agarwal et al, (1982) Ind. J. Chem., 2IB, 545; J. March, (1992), Aromatization of Six membered rings. In: Advanced Organic Chemistry (4th ed.) Academic Press; House et al. (1989) J.A.C.S.lll, 5970; A. Jenson et al. (1957) Compt. Rend. 245, 183; Chopra et al. (1973) Ind. Perf. 17(2), 69; Croft et al. (1981) Tetrahedron. 37(2), 383]. In these process cyclic terpene ketones are treated with one or more of the above mentioned reagents usually in liquid phase and rarely in vapour phase. Most of these dehydrogenation procedure suffers from one or other drawback for want of yield and side reactions. It is especially true when reactions are carried out in vapour phase. No concrete information is available in the literature about any catalyst which could bring about the quantitative conversion of cyclic ketones without any side reactions into corresponding phenols and related compounds. Moreover, there is no mention of using the supported metal atom dispersed catalyst for the oxidation of cyclic ketones into corresponding phenols, hence the necessity for development of such catalysts. Some of the catalysts mentioned above are even employed on a commercial scale but are nonspecific due to side reactions and are accompanied by undesirable side products above tolerable limits, which are difficult to separate economically. These processes are also time consuming and are quite complicated. The present invention provides a specific catalyst to convert cyclic ketones into phenols such as menthone, isomenthone, menthone-isomenthone mixture, piperitone and pulegone etc. into thymol and related compounds in quantitative yield without side reactions along with the separation of catalyst of high purity from starting materials for recycling. No prior art is available in the literature concerning the present invention. Therefore, invention of a direct, economical and stereospecific isomerization catalyst for the conversion of cyclic ketones into phenols in a single step without side reactions is advantageous. Further, the starting components being the easily available salts and support materials the final catalyst is of high value for dehydrogenation and oxidation of substituted cyclic ketones into phenols. The main objective of the present invention is to provide a process for the production of novel catalyst useful for dehydrogenation reaction which obviates the drawbacks as detailed above. Another objective of the present invention is to develop the direct process for the production of highly active and selective supported metal atom dispersed catalysts for oxidation/dehydrogenation/aromatization of such cyclic terpene ketones into phenols in a single step under continuous vapour phase and liquid phase without any side reactions, in varied solvent media under optimum conditions of temperature, pressure, pH and time. Yet another objective of the invention is to develop novel basic supported metal catalyst in such a way which will only oxidize and aromatize the cyclohexane ring without affecting the other part of the molecule so as to give the maximum yield of the product. Yet still another objective is that by employing the catalyst and conditions mentioned in the invention, the formation of undesired side products is minimized and catalyst recovered for reprocessing. Accordingly the present invention provides a process for the preparation of novel catalyst useful for dehydrogenation reactions which comprises; reacting metals from group VIII selected from Fe, Co, Ni and group IB metals selected from Cu, Ag, Au in presence of promoters or initiators selected from group VI and VII B metals comprising Cr, Mo, W, Mn, Tc and Re or their salt either as such or in combination with, alkali and alkaline metal salts selected from calcium carbonate, sodium carbonate, sodium bicarbonate, sodium hydroxide, in an organic solvent such as herein described, at a temperature in the range of 0 - 100°C, for a period in the range of 0.5 - 2.5 hrs. and mixing the resultant with a solid support such as herein described, removing the solvent by conventional methods, heating the obtained residue, at a temperature in the range of 160-600°C, for a period in the range of 8 - 16 hrs, to get the desired catalyst. In an embodiment of the present invention the group VIII metals may be such as Fe, Co, Ni families and group IB metals may be such as Cu, Ag, Au and alkali and alkaline metal salts may be such as calcium carbonate, sodium carbonate, sodium bicarbonate, sodium hydroxide.. In an embodiment of the present invention the solvent used may be such as pyridine, decane, dodecane, hexadecane, alcohols like isopropanol, ethanol, ethylene glycol, acetone and water. In another embodiment of the invention the support used may be such as inert, basic or acidic alumina, silicagel, ceramic, kieselguhr, Bentonite, Askansk clay, Askonite etc. In yet another embodiment the promoters and initiators used may be such as metals and salts of group VI and VIIB like Cr, Mo, W, Mn, Tc and Re. The first class of catalysts comprises materials which are essentially simple or complex platinum group metal (Ru, Rh, Pd, Pt) salts and supported noble metals which are suitably used in the media either as such or in combination with alkali and alkaline metal hydroxides and oxides and phase transfer medium. The second class of catalysts comprises metal atom dispersed catalyst consisting of metals or salts from group VIII (Fe, Co, Ni) and group IB (Cu, Ag, Au). In some cases combination of metals reacts readily with above type of organic compounds. In other cases the reaction is so sluggish that it is desirable to use a promoter or initiator to speed up the reaction between catalyst and ketone. Metals or their salts of group VI and VIIB like Cr, Mo, W, Mn, Tc and Re may act as promoters. Nickel and cobalt are important hydrogenation and dehydrogenation catalysts because of their ability to chemisorb hydrogen. Raney Nickel is one of the most important catalysts of nickel and is used widely in laboratory and industrial hydrogenation and dehydrogenation processes. It is the most active and the least specific nickel catalyst and also has been used in continuous hydrogenation processes but is not suitable for continuous dehydrogenation processes. The activity and specificity of nickel catalyst is also very much dependent upon its method of preparation and other parameters of temperature, time and mode of addition. A variety of nickel catalysts are available which are used for specific purposes. The dehydrogenation of cyclic terpene ketones in the presence of Raney Nickel is a complex process and mixture of atleast three products viz, aromatic alcohols, unsaturated alcohols and saturated alcohols, may well be obtained. In general, mild conditions lead to a predominance of saturated alcohols whilst more forcing conditions favour the aromatic alcohols. Raney Nickel in general, cannot be used directly for the dehydrogenation of ketonic functions in presence of isolated olefinic centers because of its activity to hydrogenate such centers which acts as hydrogen acceptors. It is therefore, required to modify the catalyst in such a way that restricts its hydrogen acceptor activity and disproportionation reactions. It is, therefore, the purpose of this invention to devise a suitable modified Nickel catalyst which could dehydrogenate the cyclic terpene ketones without hydrogenating the olefinic portion of side chain in the molecule. We have found that although noble metal and metal atom dispersed catalyst (Fe, CO, Ni) give dehydrogenated products more or less in good amounts but the selectivity and yields were more pronounced when the catalysts were supported on inert, basic and neutral supports like, alumina, silica gel, ceramics, kieselguhr, bentonite, Askansk clay, Askonite etc. We have found that the most suitable catalyst for the present inventions comprises a class consisting of highly active and selective supported modified metal atom dispersed catalyst at suitable temperature applied under conditions of dehydrogenation in the presence of hydrogen above atmospheric pressure. In some cases mineral acids, inorganic and organic bases and salts of Group VI and Group VII metals are used as modifiers to retard or check the hydrogenation of isolated olefinic centers. Nickel catalyst suitable for the present operation is prepared from nickel salts in the presence of modifiers like organic and inorganic bases and/or in the presence of salts of Group I and Group VII metals and by leaching of salts with alkali and alkaline metal salts at a temperature of 0°-600°C. The catalysts comprises of combination of highly active and selective bimetallic nickel type supported metal atom dispersed catalysts (Ni-Fe-Co-Cu-support), prepared from group VIII metals (Fe, Co, Ni families) and/ or their salts either alone or in combination with metals of group 1B (Cu, Ag, Au ) along with or without promoters in different proportions. In some cases combination of metals so selected react, readily with above type of organic compounds. In other cases the reaction is so sluggish that it is desirable to use promoters or initiators to speed up the reaction between catalyst and ketones. Such promoters and initiators may be the metals or their salts of group VI B and VII B like Cr, Mo, W, Mn, Tc and Re. We have found that although metal atom dispersed catalyst described above afford dehydrogenation products more or less in good amounts; the selectivity and yields were more pronounced in favour of phenols, when the catalysts were supported upon inert, basic or acidic supports like alumina, silica gel, ceramic, kieselguhr, Bentonite, Askansk clay, Askonite etc. Depending on the system the catalysts can be prepared and utilized directly or can be stored as per requirements. The catalysts so invented are suitable for operations under continuous vapour phase systems and batch processes at elevated temperature and pressure and various pH range. In some instances the combination was found to be the best when generated in situ. In general the usual relationship of time, temperature activity of catalyst, ratio of activity to volume of catalyst etc. apply in the present case. In vapour phase systems by adjustment of flow rate of ketones to catalyst ratio (ml of ketone/g. of catalyst/ hour) and diameter to height ratio etc., conversion of upto 65% has been achieved in a single run without any side reactions; theoretically means 90-100% selectivity. The invention is described further with reference to the examples given below . These examples should not be construed as to restrict the scope of the invention. Example 1 Nickel sulphate (50 g), copper sulphate (20 g), sodium carbonate (50 g), sodium bicarbonate (50 g ), and distilled water (350 ml), were mixed gently at 0° C and later temperature raised to 100° C, The reaction mixture so obtained was mixed with manganese sulphate (7.4 g) and alumina (100 g) and solvent distilled off. The dry residue was pelted into pellet of 0.4 g each and heated at 600°C for 6 hours. Example 2 Cobalt nitrate (75 g), Nickel nitrate (75 g), silver nitrate (5 g), sodium carbonate (65 g ), silicagel (500 g) and distilled water (550 ml ) were mixed together at 20° C and later raised to 47° C for 2 hrs and solvent distilled off. The dry residue was pelted into pellet and heated at 360°C for 12 hours to dark grey to black coloured catalyst. Example 3 Nickel chloride (150 g), copper sulphate (60 g), sodium hydroxide (16 g), kiselghur (200 g) and distilled water (440 ml ) were allowed to react together to provide light green blue coloured reaction mixture. The reaction mixture so obtained was mixed with basic alumina (200 g) and solvent distilled off. The dry residue was pelted into pellet of 0.50 g. and heated at 290°C for 12 hours and 490° C for 2 hrs. Further the catalyst was kept in stream of nitrogen at 230° C under reducing atmosphere to provide highly active dark grey to black coloured catalyst suitable for dehydrogenation of cyclic ketones into phenols. Example 4 Nickel sulphate (90.0 g), ferrous sulphate (50 g), copper sulphate (25.0 g), cuprous chloride (3.0 g ), aluminum isopropoxide (220 g ), manganese sulphate (2.4 g ), isopropanol (1.5 lit), sodium carbonate (65 g) and distilled water (500 ml) were brought together to react gently. Solvent was distilled off. The dry residue was pelted into 0.25 g of each pellet and activated at 310°C to black coloured catalyst suitable for dehydrogenation of cyclic ketones into phenols. Example 5 Nickel sulphate (90.0 g), ferrous sulphate (50 g), copper sulphate (25.0 g), cuprous chloride (3.0 g ), aluminum isopropoxide (220 g), manganese sulphate (2.4 g), isopropanol (1.5 lit), sodium carbonate (65 g) and distilled water (500 ml) were brought together to react gently with slow addition of Bentonite (230 g). Solvent was distilled off. The dry residue was pelted into 0.25 g of each pellet and activated at 200°C to black coloured catalyst suitable for dehydrogenation of cyclic ketones into phenols. Example 6 Nickel sulphate (50 g), copper sulphate (20 g), calcium carbonate (50 g), sodium bicarbonate (50 g ), and distilled water (350 ml ), were mixed gently at 0° C and later temperature raised to 100° C, The reaction mixture so obtained was mixed with manganese sulphate (7.4 g) and alumina (100 g) and solvent distilled off. The dry residue was pelted into pellet of 0.4 g each and heated at 560°C for 6 hours. Advantages: 1. The invented bimetallic supported catalysts are highly selective and suitable for dehydrogenation of cyclic ketones into phenols in high yields. 2. The bimetallic Nickel catalysts are suitable for operation in both continuous vapour phase systems and batch processes under elevated conditions of temperature and pressure. 3. Depending on the system the catalysts can be prepared and utilized directly or can be stored as per requirements. We Claim: 1. A process for the preparation of novel catalyst useful for dehydrogenation reactions which comprises; reacting metals from group VIII selected from Fe, Co, Ni and group IB metals selected from Cu, Ag, Au in presence of promoters or initiators selected from group VI and VII B metals comprising Cr, Mo, W, Mn, Tc and Re or their salt either as such or in combination with alkali and alkaline metal salts selected from calcium carbonate, sodium carbonate, sodium bicarbonate, sodium hydroxide, in an organic solvent such as herein described, at a temperature in the range of 0 - 100°C, for a period in the range of 0.5 - 2.5 hrs. and mixing the resultant with a solid support such as herein described, removing the solvent by conventional methods, heating the obtained residue, at a temperature in the range of 160-600°C, for a period in the range of 8 - 16 hrs, to get the desired catalyst. 2. A process as claimed in claim 1, wherein the organic solvent used is selected from pyridine, decane, dodecane, hexadecane, isopropanol, ethanol, ethylene glycol, acetone and water. 3. A process as claimed in claims 1 and 2, wherein the solid support used is selected from basic or acidic alumina, silicagel, ceramic, kieselguhr, Bentonite, Askansk clay, Askonite. 4. A process for the preparation of novel catalyst substantially as herein described with reference to examples.

Documents:

636-del-1999-abstract.pdf

636-del-1999-claims.pdf

636-del-1999-complete specification (granted).pdf

636-del-1999-correspondence-others.pdf

636-del-1999-correspondence-po.pdf

636-del-1999-description (complete).pdf

636-del-1999-form-1.pdf

636-del-1999-form-19.pdf

636-del-1999-form-2.pdf

636-DEL-1999-Form-3.pdf