Title of Invention	"A PROCESS FOR THE PRODUCTION OF ALPHA PICOLINE"
Abstract	A process for the preparation of 2-picoline and 4-picoline by vapour phase catalytic reaction with acetaldehyde and ammonia is disclosed. The reaction is carried out in the in presence of a catalyst comprising of cobalt aluminum phosphate which has been impregnated with 2% to 12% by weight of phosphoric acid and 2 to 12% lead as co-promoter.

Full Text

Process for the production of Alpha picoline Field of the Invention: The present invention relates to a process for producing alpha-gamma picoline with more alpha ratio by gaseous phase catalytic reaction of acetaldehyde with ammonia by using a novel catalyst. Background of the Invention: Pyridine bases are valuable intermediates used in production of dyes, medicines, agriculture chemicals and they are important also as solvent. Moreover, corresponding vinyl monomers are prepared from 2 or 4 methyl pyriclines and their application fields are now expanding because such vinyl monomers are suitable as co-monomer for production of synthetic rubbers or synthetic fibers. But now-a-days, demand of 2-picoline is more as tyre cords, adhesives, herbicides, fertilizers, additives and raw materials for medicine are growing, whereas demand for 4-picoline has been stable. Thus, a process or catalyst capable of producing 2-picoline selectively in high yield has been so far desired to fulfill market demand. According to the present invention, 2-picoline can be selectively produced from acetaldehyde(mixed with water) and ammonia at a ratio of formation of 2-picoline to 4-picoline at about 6.5-7.0:1 mole ratio, when a phosphate of two metals such as cobalt aluminium phosphate is impregnated with an aqueous solution of phosphoric acid and lead. Discussion of Prior Art: Methods for producing pyridine bases from acetaldehyde and ammonia have been known in the past. U.S. Patent No. 6,281,362 describes a method for producing pyridine bases which gives improved yield in the presence of a zeolite containing titanium and/or cobalt and silicon as zeolite constituent elements in which max. 3:1 ratio of alpha to gamma is claimed. Another U.S. Patent No. 4239,892, describes a process for producing pyridine bases on silica alumina catalyst with different metals in which equal amounts of alpha to gamma picoline is formed. U.S. Patent No. 3932,421 by Koei Chemical Company discloses a process in which 2-picoline can be selectively produced from acetaldehyde and ammonia at a ratio of formation of 2-picoline to 4-picoline at 5:1 by mole, when a phosphate of two metals such as cobalt aluminum sulphate, cobalt magnesium phosphate and lead aluminum phosphate impregnated with an aqueous solution of phosphoric acid or ammonium phosphate is used as catalyst. U.S. Patent No. 4,179,576 discloses a process for preparing pyridine bases including 2-methyl pyridine and 4-methyl pyridine, together with pyridine from acetaldehyde and ammonia by gas phase catalytic reactions, but almost equal amount of 2-methyl pyridine to 4-methyl pyridine is formed. U.S. Patent No. 4,388,461 discloses a process for producing alpha picoline by the ammoniation of phenol over a zeolite having a silica alumina ratio of at least 12 and a constraint index of 1 to 12. The preferred zeolite is ZSM-5. Aniline is produced as a co-product and the alpha-picoline may be separated by distillation or extraction. But yield of alpha picoline is very less. Therefore , there is a need to develop a novel catalyst for producing more alpha-picoline in alpha gamma picoline reaction. Objects of the Invention: The main object of the present invention is to produce more alpha picoline in alpha-gamma reaction by gaseous phase catalytic reaction of acetaldehyde with ammonia by using cobalt aluminum phosphate catalyst, impregnated with phosphoric acid and modified with lead. Another object of the present invention is to improve the yield of alpha-gamma picoline. Detailed Description of the Invention: The major emphasis of the present invention is to enhance the ratio as well as yield of alpha picoline in alpha-gamma reaction. According to the present invention 2-picoline can be selectively produced from acetaldehyde and ammonia at a ratio of formation of 2-picoline to 4-picoline at about 6.5-7.0:1 by molar ratio in the presence of a catalyst comprising of a phosphate of two metals such as cobalt aluminum phosphate, impregnated with an aqueous solution of phosphoric acid followed with solution of lead salt. Cobalt aluminum phosphate catalyst was prepared and studied by varying the percentage of promoter and modifiers. When cobalt aluminum phosphate with 4% phosphoric acid was used as a catalyst, the yield of alpha and gamma picoline was 55-56% (overall 67% yield) and ratio of alpha to gamma 5:1 max., but when catalyst of this invention, cobalt aluminum phosphate promoted with 4% phosphoric acid and modified with 2-15% lead was used then the yields were increased to 60-63% of alpha and gamma (with overall bases 70-73% yield) and ratio of alpha to gamma, 7:1. In the present invention, it is desirable to react acetaldehyde with ammonia in the range of 1:1.15-1.5 over the said catalyst at a reaction temperature of 400 to 475 deg.c. and a space velocity(S.V) of 400 to 1500 hr-1. The reaction was carried out in a fixed bed reactor of stainless steel having an inner diameter of 31 mm and height of one meter. Provision for feeding the reactants like acetaldehyde and ammonia were made separately through rotameter and peristaltic feed pumps. Exit gases were cooled and condensed. Uncondensed gases were vented through a water scrubber. Samples were periodically drawn from the condenser pot for analysis. Scale up studies were carried out in a 1 mtr. long 1-1/2" I.D. reactor equipped with 3 zone heating system and provisions for measured input of reactants. The first zone of the reactor worked as pre-heater for the reactants whereas the second and third zones were used as the catalyst zone or the reaction zone. The present invention will be explained in detail, referring to the examples. The yield used in this invention are calculated by the following formula: Carbon content of the pyridine base formed Yield(%) = x 100 Carbon content of the starting material aldehyde The reaction temperature at which the process of present invention works is in the range at 400 to 475°C . preferably between 425 to 445°C.. When the reaction temperature is too low, the conversion is low and acetaldehyde is mainly obtained in the form of acetaldehyde ammonia adduct which forms crystalline solid mass in the condenser. When the reaction temperature is too high, decomposition or carbonization of the product is remarkably increased and the yield of the intended product is lowered. Catalyst Preparation Details: 650 gm of an aqueous solution containing 180 gm of Diammonium monohydrogen phosphate and 1400 gm of an aqueous solution containing 192 gm of cobalt acetate and 250 gm of aluminum nitrate were mixed at a temp, of 55 to 60 deg.c. under agitation and maintained for one hour. A blue colour precipitate, phosphate of two metals having a composition of CO3 A12(PO4)4 was obtained. The solution was neutralized with ammonia water by maintaining the pH between 7 to 7.3. The whole solution was maintained under stirring for one hour and re-adjusted the pH. Precipitate was filtered washed with DM water thoroughly and dried at 120 deg.c. for 2 hours and calcined at 550 deg.c. for 5 hours. Thus prepared catalyst was impregnated with phosphoric acid and with lead acetate following the normal impregnation technique and results shown in table 1 to table -3. The following examples further illustrate the present invention more specifically, but do not limit the scope of the present invention. Example-1: 500 g of the dried precipitates prepared in substantially the same manner as described in the catalyst preparation details were impregnated with an aqueous solution of 2%, 4% and 8% by weight of phosphoric acid, dried and molded to pellets having diameters of 2-3 mm. 250 cc of this prepared catalyst was packed in one meter fixed bed reactor. 110 gm chilled acetaldehyde was mixed with 40 gm of chilled demineralized water below 15deg.c, thus 150 g/hr feed kept at low temperature and 50 g/hr of ammonia were mixed in vapourizer at 250 deg.c., and the resulting mixture was passed through the reactor for 10-12 hours, while keeping the reactor at a temperature of 460 deg.c. The reaction product was cooled in cooling chamber and the gases were circulated in the scrubber. After the completion of the reaction, N2 gas was passed through the reactor to flush the reactor. For regeneration of the catalyst air and nitrogen mixture were passed through the reactor, thus carbonaceous materials deposited on the catalyst during the reaction was combusted at a temperature of 500 to 550 deg.c. to regenerate the activity of the catalyst and it was found that even up to 15 regenerations, there was no reduction in the catalyst activity. For comparison, the results obtained when different ratio of phosphoric acid were impregnated in the above said catalyst are shown in the table. Table:1 Yields of the product on different ratio of Phosphoric acid in the Catalyst (Table Removed) Example-2: 4%, 6% and 8% lead was impregnated in 4% phosphoric acid containing catalyst in the same manner as described in example-1, gas phase catalytic reactions were carried out under the similar conditions as described in example-1 and results are shown in table-2. Table:2 Yields of the product when lead was impregnated on 4% phosphoric acid based Catalyst (Table Removed) Example-3: Catalyst of example-2 with 6% lead as promoter was screened for 12 hours continuously and the results are tabulated in following table ( no.3) Table :3 Time on Stream Study (Table Removed) Example-4: By using the same catalyst as prepared in example-3, 15 repetitions of reaction and regenerations were carried out to check the reproducibility and catalyst activity. The results are shown in table-4. It is evident that there is no decrease in the catalyst activity even after 15 sets of reactions and the initial level of activity is maintained. It was also observed that regeneration enhanced to some extent the catalyst selectivity towards alpha picoline during the reaction. Table:4 Catalyst life cycle study and regeneration (Table Removed) We claim: 1. A process for the preparation of 2-picoline and 4-picoline by vapour phase catalytic reaction with acetaldehyde and ammonia wherein said reaction is carried out in the in presence of a catalyst comprising of cobalt aluminum phosphate which has been impregnated with 2% to 12% by weight of phosphoric acid and 2 to 12% lead as co- promoter. 2. A process according to claim-1, wherein lead was selected from it's salt like lead acetate, lead nitrate, lead formate etc. 3. A process according to claim-1 or 2, where the yield of 2-picoline and 4-picoline is about 62 to 63 mole% and 70-73 mole% including all other bases. 4. A method according to any preceding claims where aqueous solution of lead salt is used. 5. A process according to any preceding claim wherein said phosphoric acid and lead are both impregnated. 6. A process according to any preceding claim wherein said vapour phase reaction is carried out at a temperature in the range of 400 to 475°C preferably, between 425 to 445°C. 7. A process for the preparation of 2-picoline and 4-picoline substantially as herein described with reference to the foregoing Examples.

Documents:

1194-del-2002-abstract.pdf

1194-del-2002-claims.pdf

1194-DEL-2002-Correspondence-Others-(17-03-2011).pdf

1194-del-2002-correspondence-others.pdf

1194-del-2002-correspondence-po.pdf

1194-del-2002-description (complete).pdf

1194-del-2002-form-1.pdf

1194-del-2002-form-19.pdf

1194-del-2002-form-2.pdf

1194-DEL-2002-Form-27-(17-03-2011).pdf

1194-del-2002-form-3.pdf

1194-del-2002-gpa.pdf