Title of Invention

"A PROCESS FOR THE PREPARATION OF HETEROAROMATIC NITRILES"

Abstract

The present invention discloses preparation of heteroaromatic nitriles by the ammoxidation of the corresponding alkyl substituted pyridine using ammonia and an oxygen source, the use of the catalyst of the invention results in avoiding formation of undesirable by-products, use of low reaction temperatures, good yield and selectivity for the desired nitriles, and simpler reaction protocols. The invention provides a process for the preparation of a heteroaromatic nitrile comprising reacting the corresponding alkyl substituted pyridine with ammonia and an oxygen source in presence of a catalyst comprising, as the active components, vanadium, antimony and phosphorous containing compounds supported on a carrier.

Full Text

PROCESS FOR THE PRODUCTION OF HETEROAROMATIC NTTRILES, IMPROVED CATALYST THEREFOR AND A PROCESS FOR THE PRODUCTION OF SATO IMPROVED CATALYST Field of the invention The present invention relates to a process for the preparation of heteroaromatic nitriles by the selective ammoxidation of the corresponding alkyl substituted pyridine. More particularly, the present invention relates to a process for the preparation of a heteroaromatic nitrile by reacting the corresponding alkyl substituted pyridine with ammonia and molecular oxygen and/or air in gas phase over an improved catalyst. The present invention also relates to such improved catalyst useful in the preparation of heteroaromatic nitriles and to a process for the preparation thereof. Background of the invention Heteroaromatic nitriles are valuable Intermediates used in the preparation of a wide range of medicines and agro-chemicals. Several processes are known in the art for the production of heteroaromatic nitrile from the corresponding alkyl substituted pyridine by reacting the alkyl substituted pyridine with ammonia and oxygen and/or air at elevated temperature in the gas phase. The prior art processes differ from each other in respect of the reaction conditions and/or the catalyst used. Generally, only those catalysts, which show good selectivity and high space time yield are suitable for use on an industrial scale. A significant problem in prior art ammoxidation processes used for the preparation of heteroaromatic nitriles is that they require reaction gases, which are greatly diluted with air. As a result, the space time yield is very low resulting in lower production of the desired nitriles. Another problem faced in processes where excess oxygen is used is the formation of undesirable byproducts rather than the desired nitriles due to the combustion of organic reactant and ammonia. This adds to process cost as more raw materials are required to produce a given amount of nitrile and also larger capital investment is required for a plant for a given capacity. It is therefore important and essential to develop a catalyst and a process for the ammoxidation of alkyl substituted pyridine to the corresponding heteroaromatic nitrile, which provides an improved selectivity as well as productivity for the desired heteroaromatic nitriles. Description of prior art Several processes for the preparation of heteroaromatic nitriles by catalytic ammoxidation of corresponding alkyl substituted pyridines with ammonia and oxygen and/or air in gas phase are reported in the art. US Patent No. 2592123 discloses a molybdenum oxide catalyst for the preparation of cyanopyridine at a temperature of over 410°C. The disadvantages of this process are the high reaction temperature which is not suitable for industrial production and also low yield of cyanopyridine. Another disadvantage of this process is that the catalyst gets deactivated in the course of time during reaction necessitating periodic regeneration resulting in higher production costs. US Patent No. 2839535 discloses a vanadium oxide catalyst applied to pretreated alumina for the preparation of cyanopyridines. In the process of this patent the treatment of Alumina is done at a temperature of 1100° to 1350°C, which makes the process of catalyst preparation unsuitable. European Patent No. 0037123 uses a catalyst comprised of vanadium, antimony and uranium or chromium oxides mixed with alumina. The required calcination temperature for the catalyst is 1300°C, which is again not suitable for industrial operatioa The process of this patent also requires that the reaction gases be diluted with air, thereby resulting in lower productivity and very high uncondensable gaseous effluent. US Patent No. 3,927,007 discloses a catalyst produced by pre-treating mixtures containing antimony and vanadium and at least one of the elements iron, copper, titanium, cobalt, manganese and nickel and optionally a carrier substance by heating to a temperatures of 600 to 1100°C in the presence of oxygen. While the process of this patent results in high space time yields, the selectivity is unsatisfactory. US Patent No. 3,297,587 discloses in borophosphate catalysts activated with molybdenum, bismuth, vanadium, iron or cobalt. The catalyst of this process are unsuitable since it is partly split into boric acid and phosphoric acid. US Patent No. 2510605 discloses a catalyst containing vanadium, molybdenum and phosphorous with alumina as a carrier. While the yield is reported to be good at 450°C, the high reaction temperature and high dilution of feed with air makes this process industrially undesirable. European Patent No. 0253360 discloses vanadium, phosphorous and antimony oxides in combination as catalyst for the ammoxidation at a reaction temperature in the range of 420 -430°C. Again, the high operating temperature is a serious limitation in terms of industrial operation. US Patent No. 5,910,465 discloses the ammoxidation of picolines over a multi-component catalyst comprising of vanadium, phosphorous, titanium or aluminium oxide with or without bismuth oxide. The catalyst is reduced at 450°C before the reactants are passed over the catalyst. US Patent No. 3,970,657 discloses the use of V2O5 + MoO3 + P2O5 + MnSO4 with titanium dioxide. The conversion level of 3-picoline claimed in this disclosure is in the range of 52% and selectivity of upto 83%. The low conversion and selectivity levels render this process unattractive. US Patent No. 5,658,844 discloses the use of vanadium, antimony, silica and titanium dioxide with one or more alkali metals. US Patent No, 4057552 discloses the use of a fluidlzed bed reactor. In this disclosure, a part of the spent catalyst is withdrawn from the ronetor niul volnillc components are removed from the catalyst by stripping. The spent catalyst is then oxidized by molecular oxygen through regeneration and the regenerated catalyst is re-circulated into the reactor. The reaction protocol of this process is complicated and the selectivity of 3-cyanopyridine is as low as 15%. Some of the problems associated with the prior art are overcome by the process disclosed in the applicants copending patent application No. 936/DEL/2001. The process of this application discloses the preparation of a heteroaromatic nitrile from the corresponding alkyl pyridine by contacting the alkyl pyridine with ammonia and an oxygen source in the presence of a catalyst comprising an active component consisting of oxides of vanadium and antimony and at least one promoter selected from chromium, molybdenum, cobalt and manganese oxides and any mixture thereof provided on a support. The oxygen source is preferably air. However, this process requires reaction gases to be highly diluted with air which results in lower productivity and high uncondensable gaseous effluents. As can be seen, prior art processes suffer from several problems such as high reaction temperature, low yield and selectivity for the desired heteroaromatic nitrile, requirement of excess air, catalyst deactivation and other operational difficulties. Another significant problem of vanadium oxide catalysts is their strong catalytic activity resulting in the dealkylation or cleavage of the heteroaromatic ring thereby reducing the yield and selectivity of the desired nitriles. Objects of the invention It is therefore an object of the present invention to provide a process for the production of heteroaromatic nitriles by the amnioxidation of the corresponding alkyl substituted pyridines with ammonia and oxygen and/or air which ensures higher selectivity of the desired product at low temperature. It is another object of the present invention to provide a process for the production of heteroaromatic nitriles by the amnioxidation of the corresponding alkyl substituted pyridines with ammonia and oxygen and/or air in the presence of an improved catalyst, thereby ensuring higher selectivity of the desired product at low temperature. Another object of the present invention is to provide a process for the production of heteroaromatic nitriles by the amnioxidation of the corresponding alkyl substituted pyridines with ammonia where the amount of oxygen and/or air hi the feed is kept at a minimum in order to improve the productivity at industrial scale. Another object of the present invention is to provide a process for making an improved catalyst used in the manufacture of heteroaromatic nitriles whose preparation is comparatively simple and which provides high selectivities of the desired products. It is another object of the present invention to provide a process for the preparation of an improved catalyst for the ammoxidation of an alkyl substituted pyridine to the corresponding heteroaromatic nitrile, in which catalyst can be used nl lower reaction temperature and does not require frequent regeneratioa Summary of the invention After extensive research and analysis, the applicants have found that in the preparation of heteroaromatic nitriles by the ammoxidation of the corresponding alkyl substituted pyridine using ammonia and an oxygen source, the use of the catalyst of the invention results in avoiding formation of undesirable by-products, use of low reaction temperatures, good yield and selectivity for the desired nitriles, and simpler reaction protocols. Accordingly, the present invention provides a process for the preparation of a heteroaromatic nitrile comprising reacting the corresponding alkyl substituted pyridine with ammonia and an oxygen source in presence of a catalyst comprising, as the active components, vanadium, antimony and phosphorous containing compounds supported on a carrier. In one embodiment of the invention, the vanadium containing compounds are selected from V205, V204, V2O3 and vanadates. In another embodiment of the invention, the vanadate comprises ammonium vanadate. In another embodiment of the invention, the antimony containing compounds are selected from Sb2O3, Sb2O4 and Sb2O5. In another embodiment of the invention, the phosphorous containing compound is selected from the group consisting of orthophosphoric acid, metaphosphor'c acid and phosphorous acid. In yet another embodiment of the invention, the catalyst support is selected from the group consisting of silica, alumina and preferably, titanium dioxide with surface area In another embodiment of the invention, the ratio of vanadium containing compound, antimony containing compound and phosphorous containing compound in the final catalyst composition is per atom of vanadium, 0.1 to 5 of phosphorous, preferably 0.5 to 3, most preferably 0.8 to 2.0 and 0.5 to 10 of antimony, preferably 1 to 5 and most preferably 1.5 to 3. In another embodiment of the invention, the amount of the active component of the catalyst on the support is not less than 5 wt% preferably not less than 10 wt%. In another embodiment of the invention, the oxygen source is selected from air or pure oxygen or a mixture of pure oxygen and air or nitrogen. In a further embodiment of the invention, the gaseous reaction mixture containing the alkyl pyridine, air and ammonia is diluted with steam. In yet another embodiment of the invention, the molar ratio of alkyl pyridine to steam is in the range of 1:2 to 14 moles preferably 1:2 to 12 moles and most preferably 1:4 to 10 moles. In another embodiment of the invention, for every mole of alkyl pyridine, 1 to 12 moles, preferably 2 to 8 moles and most preferably 2 to 4 moles of ammonia, 5 to 25 moles, preferably 8 to 20 moles and most preferably 10 to 16 moles of air and 2 to 14 moles, preferably 2 to 12 moles and most preferably 4 to 10 moles of steam are used. In yet another embodiment of the invention, the catalyst is provided hi the form of a fixed bed. In a further embodiment of the invention, the alkyl substituted pyridines comprise 2-methyl pyridine, 3-methyl pyridine, 4- methyl pyridine, a mixture of picolines and various lutidines. In a further embodiment of the invention, the alkyl substituted pyridine comprises 3-methyl pyridine to get 3-cyanopyridine. In a further embodiment of the invention, the alkyl substituted pyridino comprises 4-methyl pyridine to get 4-cyanopyridine. In a further embodiment of the invention, the alky] substituted pyridine comprises 2-methyl pyridine to get 2-cyano pyridine. In a further embodiment of the invention, the alkyl substituted pyridine comprises a mixture of picolines to get a mixture of cyanopyridines. In a further embodiment of the invention, the alkyl substituted pyridine comprises lutidine to obtain corresponding mono or dinitrile. In another embodiment of the invention, the reaction is carried out at a temperature in the range of 320-390°C, preferably at a temperature between 340°C and 390°C and most preferably about 340 to 375°C. In a further embodiment of the invention, the reaction is carried out under atmospheric pressure, or slightly positive pressure. In a further embodiment of the invention, wherein the space velocity (at STP) maintained is 300 - 2000 hr"1, preferably 500 to 1800 hr"1 and most preferably 800 to 1500 hr"1. In a further embodiment of the invention, the alkyl substituted pyridine is contacted with the catalyst in the form of vapour. In a further embodiment of the invention, the molar ratio of alkyl substituted pyridine to air is in the range of 1:5-25, preferably 1:8-20 and most preferably 1:10-16. In a further embodiment of the invention, the molar ratio of alkyl substituted pyridine to ammonia is in the range of 1:1-12 preferably 1:2-8 and most preferably 1:2-4. The invention has a specific preferred advantage that use of steam in the process helps in controlling the reaction temperature, therefore, minimising the temperature difference across the catalyst bed. Another advantage in the present invention is that the unreacted alkyl susbtituted pyridine can be recovered and recycled back in the process and hence, improving the overall yield of the desired product. The invention also provides a process for the preparation of a novel catalyst useful in the catalytic ammoxidation of alkyl substituted pyridine to the corresponding heteroaromatic nitrile, said process comprising dissolving a vanadium source, antimony source and a phosphorous source being the active components, in a solvent, said vanadium source, antimony source and phosphorous sources being converted into the corresponding oxides in the said solvent, and then loading the active components of the catalyst from said solution into a carrier. In one embodiment of the invention, the process for the preparation of the said catalyst comprises: (a) preparing a homogenous solution of vanadium source in water; (b) adding an antimony and phosphorous source to the said solution at prescribed bed temperature to form a homogeneous solution; (c) adding a catalyst support, preferably titanium dioxide of low surface area and then evaporating the water to form a paste like material; (d) extruding and sizing the paste like material to desired dimensions; (e) calcining the extruded and sized material under desired temperature conditions to obtain the said catalyst. In one embodiment of the invention, the loading of the active components onto the support is carried out by impregnation or by precipitation and then calcining at 400-800°C. In another embodiment of the catalyst preparation process, the vanadium source is selected from the group consisting of V2O5, V204, V2O3 and vanadates. In another embodiment of the invention, the vanadate comprises ammonium vanadate. In another embodiment of the invention, the solution of vanadium source in step (a) above is prepared by heating vanadium pentoxide and oxalic acid to obtain vanadyl oxalate in DM water. In another embodiment of .the invention, the antimony containing compounds are selected from the group consisting of Sb2O3, Sb2O4 and Sb2O5, preferably antimony trioxide. In another embodiment of the invention, the phosphorous containing compound is selected from the group consisting of orthophosphoric acid, metaphosphoric acid and phosphorous acid, preferably O-Phosphoric acid. In yet another embodiment of the invention, the catalyst support is selected from the group consisting of silica, alumina and preferably, titanium dioxide with surface area In another embodiment of the invention, the ratio of vanadium containing compound, antimony containing compound and phosphorous containing compound in the final catalyst composition is per atom of vanadium, 0.1 to 5 of phosphorous, preferably 0.5 to 3, most preferably 0.8 to 2.0 and 0.5 to 10 of antimony, preferably 1 to 5 most preferably 1.5 to 3. In another embodiment of the invention, the amount of the active component of the catalyst on the support is not less than 5 wt% preferably not less than 10 wt%. In another embodiment of the invention, the catalyst contains oxides of vanadium, antimony and phosphorous in the atomic ratio of 1:0.5-10:0.1-5.0. Detailed description of the invention The preparation of heteroaromatic nitriles by the catalytic ammoxidation of the corresponding alkyl substituted pyridine using ammonia and an oxygen source over a catalyst comprising as active components vanadium, antimony and phosphorous oxides results in avoiding formation of undesirable by-products, use of low reaction temperatures, good yield and selectivity for the desired nitriles, and simpler reaction protocols. The reaction of the alkyl substituted pyridines with NHs and oxygen and/or air to form corresponding heteroaromatic nitriles takes place in a conventional manner in gas phase. The reaction condition can vary widely. The reaction is preferably carried out at atmospheric pressure or under slight positive pressure at a temperature between about 320°C and 390°C, preferably at a temperature between 340°C and 390°C and moat preferably about 340 to 375"C. It is advantageous besides to mix steam into feed. The presence of steam renders the reaction easier rather than the use of dehydrated reactants. The ratio of alkyl pyridines to ammonia, air and water can be chosen within wide limits. It is generally preferred to use per mole of alkyl pyridines, about 1 to 12 moles preferably 2 to 8 motes and most preferably 2 to 4 moles of ammonia, about 5 to 25 moles, preferably 8 to 20 motes and most preferably 10 to 16 moles of air and about 2 to 14 moles, preferably 2 to 12 motes and most preferably 4 to 10 moles of steam. The space velocity (at STP), in the process of present invention is maintained between 300 to 2000 hr-1, preferably 500 to 1800 Inland most preferably 800 to 1500 hr'1. Heteroaromatic nitrites are produced by reacting corresponding alkyl substituted pyridine with molecular oxygen and/or air and ammonia in gaseous phase in a fixed bed reactor system contain a catalyst comprised of V-Sb-P. The catalyst of the present invention is prepared by dissolving a vanadium containing compound, antimony containing compound and phosphorous containing compound being convertible into oxides through chemical reaction or heating in a suitable solvent preferably water and then impregnating them into or precipitating them on a carrier and then calcining at 400-800°C temperature. The vanadium containing compounds include various vanadium oxides eg. V2O5, V2O4, V2O3 etc. and vanadates eg. Ammonium vanadate. The antimony containing compounds include various oxides of antimony eg. Sb2O3, Sb2O4, Sb2O5, etc. The phosphorous containing compound includes orthophosphoric acid, metaphosphoric acid and phosphorous acid. The catalyst used according to the present invention may be carried out on a carrier/support such as silica, alumina and preferably titanium dioxide of surface area A formulating ratio for these vanadium containing compound, antimony containing compound and phosphorous containing compound in the final catalyst composition is per atom of vanadium, 0.1 to 5 of phosphorous, preferably 0.5 to 3, most preferably 0.8 to 2.0 and 0.5 to 10 of antimony, preferably 1 to 5 and most preferably 1.5 to 3. The amount of the active components of the catalyst to be supported varies with type of carriers used, method of preparing the catalyst, atomic ratio of the active compound and, normally is not less than 5 wt% preferably not less than 10 wt%. The alkyl substituted pyridine used includes 2-methyl pyridine, 3-methyl pyridine, 4-methyl pyridine, a mixture of picolines and various lutidines to produce corresponding heteroaromatic nitrites. The molar ratio of the alkyl pyridine to ammonia is 1:1-12 preferably 1:2-8 and most preferably 1:2-4. Air is preferably used as molecular oxygen although pure oxygen or a mixture of pure oxygen and air or nitrogen may also be used. The molar ratio of the alkyl pyridine to air is in the range of 1:5-25 preferably 1:8-20 and most preferably 1:10-16. The gaseous reaction mixture containing the alkyl pyridine, air and ammonia is diluted with steam. The molar ratio of the alkyl pyridine to steam is in the range of 1:2 to 14 moles preferably 1:2 to 12 moles and most preferably 1:4 to 10 moles. The catalyst bed temperature in the process of present invention is maintained from about 320 to 390°C, preferably 340 to 390°C and most preferably 340 to 375 °C. In the process of the present invention, space velocity (at STP) is maintained from 300 to 2000 hr-1, preferably 500 to 1800 hr-1 and most preferably 800 to 1500 hr-1. The reaction according to the present invention is carried out under atmospheric pressure or slightly positive pressure and in a fixed bed tuber reactor system. The alkyl substituted pyridine is preferably in the form of vapours when contacted with the catalyst bed. The present invention is illustrated below with reference to the following examples, which are not to be construed as limiting the scope of the invention. It must be understood that variations are possible without departing from the spirit and scope of the embodiments described below. Preparation of Catalyst Example 1 320 gm of oxalic acid was charged in 3600 ml DM water in a three neck round bottom flask fitted with thermowell and a mechanical stirrer. The temperature was slowly raised to 70°C with the help of water bath. 134 gm of V2O5 was added while maintaining the mass temperature below SOT. 400 gm SbzOs was then added at a temperature of 75-80°C. The mass was maintained at this temperature for 15-30 minutes. 180 gm of orthophosphoric acid was then added while maintaining the same temperature. This mixture was then held for approximately 1 hr. 710 gm TiO2 (anatase) (S.A. The extruded caUtlynt wan Initially calcined In air tit IOO"(J lor M hour*. The temperature was then slowly raised at the rate of 50°C/hr till a temperature of 250°C was attained. The temperature was then raised at the rate of 100°C/hr till a temperature of 530°C was attained. The temperature level was maintained for 2 hours, and then raised at the rate of 100°C/hr till a temperature of 710°C temperature was reached. The extrudate was maintained at this temperature for 3 hours. The catalyst was then discharged by cooling below 60°C. The final catalyst has a surface area 3-5 m2/gm. Experimental Set-up The above prepared catalyst was mixed with/without inert and packed in a 1 meter/5 meter long, 31 mm ID stainless steel reactor mounted on a tubular electrical furnace. A jacket with cooling arrangement device was provided in the reactor to control the catalyst bed temperature. Measured amount of feeds were separately pre-heated and mixed In a preheating zone before entering into the catalyst bed. Some inert was packed in the preheating zone to ensure the proper mixing of the feed. The temperature of the pre-mixing zone was kept at approximately 250-310°C. The product vapour were scrubbed through a series of water scrubbers connected at the reactor's outlet to avoid any loss of condensable product. The reaction product samples were analyzed periodically. Example 2 A gaseous mixture of 3-methyl pyridine, ammonia, steam and air (Mole ratio = 1:3:8:15) was fed in the reactor following the procedure described above at a space velocity (At NTP) of 1000 hr"1 at 360±10°C temperature. The water scrubbed reaction product was analysed by Gas Chromatography under stabilized process conditions. 72.0% conversion of 3-methyl pyridine with 65.0% yield and 90.28% selectivity of 3-cyano pyridine was achieved. Example 3 A gaseous mixture of 4-methyl pyridine, ammonia, steam and air (Molar ratio 1:3.5:9:14) was fed in the reactor following the procedure described above at a space velocity of 1000 hr"1 at 360+10°C temperature. The water scrubbed reaction product was analyzed by GC under stabilized process conditions. 80.0% conversion of 4-methyl pyridine with 73.0% yield & 91.25% selectivity of 4-cyanopyridine was achieved. Example 4 The same procedure as in Example 3 was carried out. Mix picoline containing (85% beta pic, 9% gnmmn pic mid rout higher pyridine hases) was used ( instend of 1-molhyl pyrlclliip) at 360+10°C. 77.0% average conversion of mix picoline .vith 64% yield and 90.14% combined selectivity of 3-cyano pyridine and 4-cyano pyridine was achieved. Example 5 A gaseous mixture of 2-methyl pyridine, ammonia, steam and air (Molar ratio 1:2.5:5:16) was fed in the reactor following the procedure described as above at space velocity 1500 hr"1 at 360+10°C temperature. The water scrubbed reaction product was analyzed by G.C. under stabilized process conditions. 72.6% conversion of 2-methyl pyridine with 48.2% yield and 66.39% selectivity of 2-cyanopyridine was achieved, Yield and selectivity of 2-cyanopyridine was comparatively low because of the formation of pyridine. Example 6 To test the viability of the process on industrial scale, experiments were carried out for longer duration in a reactor 5 times longer than the reactor used in Example 2 with similar ID. Other process conditions were kept same as in Example 2. Reaction was performed upto 800 hrs. Reaction samples were monitored periodically. The conversion of beta picoline at initial hours was 75.0% with 66.0% yield and 88.0% selectivity of 3-cyano pyridine whereas after 800 hrs of reaction, 73.1% conversion with 66.1% yield and 90.42% selectivity of 3-cyanopyridine was achieved. The experimental results above show there is no deterioration in yield and selectivity of the desired product with time end that after stubilization, performance of the catalyst Improves. Based on the above facts, it is evident that the catalyst of the present invention has a very high life and is suitable for the commercial production of heteroamutle nitrills, We claim: 1. A process for the preparation of a heteroaromatic nitrile comprising reacting the corresponding alkyl substituted pyridine of the kind such as hereinbefore described with ammonia and an oxygen source characterised in that said reaction is carried out in the presence of a catalyst comprising, as the active components, vanadium, antimony and phosphorous derived from respective sources, the ratio of phosphorus per atom of vanadium being 0.1 to 5 and the ratio of antimony per atom of vanadium being 0.5 to 10 and said reaction is carried out at a temperature of 320°C to 390°C. 2. A process as claimed on claim 1 wherein said active components are supported on a conventional catalyst support. 3. A process as claimed in claim 1 or 2 wherein the vanadium source is selected from V2O4, V2O3, and vanadates. 4. A process as claimed in claim 3 wherein the vanadate comprises ammonium vanadate. 5. A process as claimed in claim 1 or 2 wherein the antimony source is selected from Sb2O4 and Sb2O5, preferably antimony trioxide. 6. A process as claimed in claim 1 or 2 wherein the phosphorous source is selected from the group consisting of orthophosphoric acid, metaphosphoric acid and phosphorous acid, preferably orthophosphoric acid. 7. A process as claimed in claim 2 wherein the catalyst support is selected from the group consisting of silica, alumina and preferably, titanium dioxide with surface area 8. A process as claimed in any preceding claim wherein the ratio of vanadium containing compound, antimony containing compound and phosphorous containing compound in the final catalyst composition is per atom of vanadium, preferably 0.5 to 3, most preferably 0.8 to 2.0 of phosphorous and 1 to 5 and preferably 1.5 to 3 of'antimony. 9. A process as claimed in claim 2 wherein the amount of the active component of the catalyst on the support is not less than 5 wt% preferably, not less than 10 wt%. 10. A process as claimed in any preceding claim wherein the oxygen source is selected from air or pure oxygen or a mixture of pure oxygen and air or nitrogen. 11. A process as claimed in any preceding claim wherein the gaseous reaction mixture containing the alkyl pyridine, air and ammonia is diluted with steam. 12. A process as claimed in claim 11 wherein the molar ratio of alkyl pyridine to steam is in the range of 1:2 to 14 moles preferably 1:2 to 12 moles and most preferably 1:4 to 10 moles. 13. A process as claimed in claim 11 or 12 wherein for every mole of alky 1 pyridine, 1 to 12 moles, preferably 2 to 8 moles and most preferably 2 to 4 moles of ammonia, 5 to 25 moles, preferably 8 to 20 moles and most preferably 10 to 16 moles of air and 2 to 14 moles, preferably 2 to 12 moles and most preferably 4 to 10 moles of steam are used. 14. A process as claimed in any preceding claim wherein the catalyst is provided in the form of a fixed bed. 15. A process as claimed in any preceding claim wherein the alkyl substituted pyridines is selected from 2-methyl pyridine, 3-methyl pyridine, 4- methyl pyridine, a mixture of picolines and various lutidines. 16. A process as claimed in any preceding claim wherein the reaction is carried out at a temperature in the range of 340 to 375°C. 17. A process as claimed in any preceding claim wherein the reaction is carried out under atmospheric pressure or slightly positive pressure. 18. A process as claimed in any preceding claim wherein the space velocity (at NTP) maintained is 300 - 2000 hr"1, preferably 500 to 1500 hr"1 and most preferably 800 to 1500 hr-1 19. A process as claimed in any preceding claim the alkyl substituted pyridine is contacted with the catalyst in the form of vapour. 20. A process as claimed in claim 1 the molar ratio of alkyl substituted pyridine to ammonia is in the range of 1:1-12 preferably 1:2-8 and most preferably 1:10-16.

Documents:

1219-del-2001-abstract.pdf

1219-DEL-2001-Claims.pdf

1219-DEL-2001-Correspondence-Others-(17-03-2011).pdf

1219-DEL-2001-Correspondence-Others-(17-03-2011-).pdf

1219-del-2001-correspondence-others.pdf

1219-del-2001-correspondence-po.pdf

1219-del-2001-description (complete).pdf

1219-del-2001-form-1.pdf

1219-del-2001-form-19.pdf

1219-del-2001-form-2.pdf

1219-DEL-2001-Form-27-(17-03-2011).pdf

1219-del-2001-form-3.pdf

1219-DEL-2001-GPA-(17-03-2011).pdf

1219-del-2001-gpa.pdf