SK149696A3 - Catalyst mixture for oxidative ammonolysis of alkylpyridines and method of manufacture thereof - Google Patents

Abstract

A process for the preparation of a highly selective catalyst and its application in the production of cyanopyridines by oxidative ammonolysis of alkylpyridines is described. The catalytic composition is defined by the formula: Va Tib Zrc Ox, wherein a is 1, b is 7.5 to 8, c is 0 to 0.5, x represents the number of oxygen atoms necessary to satisfy the valency requirements of the elements present.

Description

Catalytic mixture for oxidative ammonolysis of alkylpyridines and process for its preparation

Technical field

The present invention relates to a process for the production of a highly selective catalyst for the production of cyanopyridines by oxidative ammonolysis of alkylpyridines and to a process for the production of cyanopyridines.

The present invention is particularly directed to the production of 3-cyanopyridine or cyanopyridine derivatives, which are important precursors for nicotinic acid or nicotinic acid amide. Nicotinic acid or nicotinic acid amide are essential vitamins of the B-complex.

BACKGROUND OF THE INVENTION

Oxidative ammonolysis of alkylpyridines is well known in the art. A wide range of catalyst systems and production methods have been described, but to date no production method is known which can meet the requirements of a commercial production method on a technical scale.

Reference is made to British Patent GB 1 317 064, which discloses a mixed catalyst system of vanadium pentoxide and titanium dioxide in a molar ratio of 1: 0.6 to 1:32 for the oxidative ammonolysis of alkylpyridines. The maximum yield of cyanopyridine obtained for the conversion of 3-methylpyridine was 89% (Example 42; V2O5: TiO2 = 1:16) and 61% for the conversion of 2-methyl-5-ethylpyridine (Example 54; V2O5: TiO2 = 1: 4). In particular, the results obtained with this known production method cannot satisfy the selectivity, yield and feed rate of alkylpyridines.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a highly selective amoxidation catalyst and an improved production process for the conversion of alkylpyridines by oxidative ammonolysis.

Disadvantages can be eliminated by the highly active catalyst prepared according to claim 1 and by the oxidative ammonolysis process according to claim 7.

Preparation of the catalyst mixture of the formula V _and Tib Zr _c O _x wherein a is 1 b is 7.5 to 8 c is 0 to 0.5, x is the number of oxygen atoms necessary to satisfy the valence requirements of the elements present include according to claim 1 the steps of coprecipitation solution W ^ ⁺ and Ti ⁴⁺ - and optionally Zr ⁴ * - compounds in water with a solution of ammonia in water, followed by exposure of the precipitate to a drying process, heat treatment and a shaping step to provide a catalytic mixture in a suitable catalyst form.

Suitable sources of the titanium component are preferably water-soluble Ti ⁴⁺ compounds such as titanium tetrachloride, titanium bromide, titanium nitrate or organic Ti-compounds such as tetraalkyl titanium compounds.

Suitable sources of the vanadium component are the water-soluble ⁵⁺ compounds, for example ammonium metavanadate.

A suitable source of the zirconium component is preferably a water-soluble Zr 4 compound such as zirconium oxychloride.

The co-precipitation is carried out while mixing the dissolved catalyst components with the aqueous ammonia solution in such a way that after the co-precipitation the pH of the liquid is between 8 and 9.

The precipitate formed can then be separated by known methods and then either first dried, preferably in an air stream at temperatures between 120 ° C and 140 ° C, or directly exposed to heat at temperatures between 360 ° C to 400 ° C, preferably in the presence of air. A conventional shaping step may then follow to suitably form the catalyst.

Preferably, tablets are formed which are preferably exposed to additional heat at temperatures between 740 ° C and 850 ° C in the presence of air.

The easy-to-prepare catalyst mixture can then be loaded into a reactor in which, after the activation stage under the reaction conditions, it is able to demonstrate its properties in terms of high activity and selectivity under high alkylpyridine loads and long life.

Preferred catalyst mixtures are:

VTi ₈ O _x

In Ti ₇₅ Zr ₀ 5 O _x

VTÍ7 5Zr _0i i25 Οχ where x is as previously defined.

The most preferred catalyst mixture is:

The Ti ₈ O _x where x it is as defined above.

The process of the present invention can be used to convert a wide range of alkylpyridines to cyanopyridines. Suitable alkyipyridines are e.g. 3-methylpyridine, 3-ethylpyridine, 2-methyl-5-ethylpyridine, 2,5-dimethylpyridine and 2-methyl-5-vinylpyridine. The most preferred alkyipyridines are 3-methylpyridine and 2-methyl-5-ethylpyridine.

The following process conditions have been shown to be suitable.

The feed gas consists of the corresponding alkylpyridine, oxygen-containing gas, ammonia and water vapor.

Air will generally be used as the oxygen-containing gas. Air provides the advantage that oxygen is already diluted with inert components.

In the case of conversion of 3-methylpyridine to 3-cyanopyridine, the feed gas is suitably composed of 3-methylpyridine, air (recalculated to O 2), ammonia and water vapor in a molar ratio from 1: 7: 3: 3 to 1: 40: 10: 45 .

A preferred range of ratios is from 1: 10: 4: 10 to 1: 30: 7: 30.

In the case of conversion of 2-methyl-5-ethylpyridine to 3-cyanopyridine and, depending on the reaction conditions, also to 2,5-dicyanopyridine, the feed gas is suitably composed of 2-methyl-5-ethylpyridine, air (O2 calculated), ammonia, aqueous vapor in molar ratio from 1: 15: 5: 20 to 1: 70: 40: 140.

The temperature in the reaction zone of the catalyst is generally between 330 ° C and 440 ° C, preferably between 350 ° C and 410 ° C.

In view of the stable life-cycle characteristics of the catalyst, the production process of the present invention can take place over a long period of time on a large scale.

The maximum achievable molar yields are about 95% to 97% for the conversion of 3-methylpyridine and about 75% for the conversion of 2-methyl-5-ethylpyridine.

The resulting cyanopyridines, i. j. 3-Cyanopyridine and / or 2,5-dicyanopyridine can be directly converted to nicotinic acid by conventional base hydrolysis. Accordingly, up to 95% yield of nicotinic acid relative to 3-methylpyridines can be achieved.

DETAILED DESCRIPTION OF THE INVENTION

Preparation of the catalyst

a) V Tig O _x catalyst.

690.4 g (3.64 mol) of titanium tetrachloride are slowly mixed with 400 ml of water at a temperature of about 60 ° C to 65 ° C. Make up the total volume to 800 ml with water.

In a separate vessel, 53.19 g (0.45 mol) of ammonium metavanadate is dissolved in 850 ml of water and 300 ml of aqueous ammonia solution under reflux conditions. During this process, ammonia is introduced into the solution.

The solution containing the V-compound is added to the Ti-solution at about 80 ° C to 85 ° C. Make up to a volume of 4 liters with water.

In a cylindrical reactor with stirring elements, 670 ml of Ti-solution at 80 ° C to 85 ° C are mixed with 670 ml of a 5.2% aqueous ammonia solution. The precipitate formed is filtered off, washed with water and dried in a stream of air at 120 ° C to 140 ° C. The resulting powder is then heated in an oven at 360 ° C in the presence of air for 2 hours, then ground in a ball mill and finally moistened with water and compressed into 4x4 mm tablets. The tablets are heated in a muffle furnace at 740 ° C for 2 hours.

The freshly prepared catalyst is then activated under oxidative ammonolysis conditions with 3-methylpyridine.

^(b ) In T17 5 Zrg 5 O _x catalyst:

The V-Ti solution is prepared as described under a).

73.27 g (0.23 mole) of zirconium oxychloride octahydrate are dissolved in 600 ml of water at a temperature between 40 ° C and 45 ° C in a separate vessel.

The co-precipitation is carried out in a manner corresponding to the process mentioned under a) by mixing 625 ml of Ti-V solution, 100 ml of Zr solution and 725 ml of said aqueous ammonia solution. Further processing of the resulting precipitate is carried out as described under a).

In T17 5 Source25 O _x Catalyst:

The procedure of Example b) was repeated without mixing 625 ml of Ti-V solution, 25 ml of Zr solution and 650 ml of said aqueous ammonia solution for co-precipitation.

Manufacturing process

Example 1:

220 cm ³ of the activated V Tig O _x catalyst was loaded into a tube reactor made of stainless steel (internal diameter 20 mm, length 1200 mm).

The layer of the catalyst was conducted 150 hours at 385 ° C the gas mixture of the reagents consisting of 3-methylpyridine (3-MP), air, ammonia and water vapor to the feed rate of 103.6 GL ^{1 h-1} 3-MP, 2727 ¹ 11 h ^_1 air, 113.8 GL ¹ h ^_1 ammonia and 336.4 G¼ ^ ^h-1 water vapor. The molar ratio in the feed was: 3-MP: air (O2): NH 3: H 2 O = 1: 22.9: 6.0: 16.8.

After 5 hours, 114 g of 3-MP were converted. Conversion complete. 119.5 g of 3-cyanopyridine were obtained, corresponding to 93.7% of the theoretical yield. The output of 3-cyanopyridine was 108 gl therefore ^_1 h ^-1.

Hydrolysis with KOH (reflux for 2 hours) gave 143.2 g (95% of theory) of nicotinic acid.

Example 2:

The same catalyst was used as described in Example 1. A reactant mixture consisting of 2-methyl-5-ethylpyridine (MEP), air, ammonia and water vapor was passed through the catalyst bed at 395 ° C. The feed molar ratio was: MEP: air (O2): NH3: H2O = 1: 25: 19: 67. 155 g of MEP was converted in 10 hours to give 93.2 g of 3-cyanopyridine corresponding to 70.5% of the theoretical yield. Thus, the production of 3-cyanopyridine was 42.8 gHh @ -1.

Hydrolysis with KOH gave nicotinic acid in a yield of 72% of theory.

Example 3:

The same catalyst (140 cm ³ ) as described in Example 1 was used. The same reactants described in Example 2 were passed through the catalyst bed at 400 ° C.

The molar ratio in the feed was:

MEP: air (θ2): ΝΗ3: Η2θ = 1: 16: 14: 30. Within 5 hours 53.2 g of MEP was converted to give 19.7 g of 2,5-dicyanopyridine (34.8% of theory) and 23.0 g of 3-cyanopyridine (50.3% of theory).

Hydrolysis with KOH gave nicotinic acid in a yield of 85.4% of theory.

Example 4:

100 cm ³ of the activated V ΤΪ7 ZRG 5, 5 O _x catalyst was loaded into a tube reactor of Example 1. The layer of catalyst was fed a gaseous mixture of 3-methylpyridine (3-MEP), air, ammonia and water vapor at 375 ° C at inlet 225 GL ¹ H1 3-MP, 344.1 gl1h1 air gľ1h 111 ^- 980 gl @ lNH3 and ^_ '' H2O. After 5 hours, 112.3 g of 3-MP was converted to give 92.1 g of 3-cyanopyridine (73.2% of theory) and 21.8 g of nicotinamide (14.8% of theory).

Hydrolysis with KOH gave 138.7 g (93.7% of theory) of nicotinic acid.

Example 5:

For the feed gas containing MEP instead of 3-MP, the catalyst of Example 4 was used. The catalyst bed temperature was 370 ° C. The feeding rate was: 80 GL ¹ h ^_1 MEP, 1225 L air, 180 g of NH 3, H 2 O 1130 g. After 6 hours, 48 g of MEP was converted to give 3.6 g of 2,5-dicyanopyridine (7% of theory) and 28.9 g of 3-cyanopyridine (70% of theory).

Hydrolysis with KOH gave nicotinic acid in a yield of 79.9% of theory.

Example 6:

100 cm ^{3 of} activated in Ti7 5 S25 Οχ catalyst were used in the same manner as in Example 4. After 5 hours 112.5 g of 3MP were converted to give 100.8 g of 3-cyanopyridine (80.1% of theory) and 17 g of nicotinamide ( 11.4% of theory).

Hydrolysis with KOH gave 139 g (93.3% of theory) of nicotinic acid.

Example 7:

For the feed gas containing 3-ethylpyridine (3-EP), the catalyst (100 cm ³ ) shown in Example 1 was used. The catalyst bed temperature was 380 ° C. The feeding rate was: 150 ^{gl-1 h-1} 3-EP, 3600 I l ^'1 h ^_1 air, 167 g | - Ir ^{1 1} NH3 and 225 gMh'I? O. After 5 hours, 75 g of 3-EP was converted to give 66.5 g of 3-cyanopyridine (91.2% of theory).

Example 8:

For the feed gas containing 2,5-dimethylpyridine (2,5-DMP), the catalyst (100 cm ³ ) shown in Example 1 was used. The catalyst bed temperature was 400 ° C. The feed rate was: 102 g ¹ L ^-1 2.5-DMP, 2095 L -1 H -1 air, 227 g H ^-1 H _3, and 650 g H ^-1 H ² O. After 5 hours, 52 g of 2,5-DMP was converted to give 18.8 g of 2,5-dicyanopyridine (30.6% of theory) and 28.8 g of 3-cyanopyridine (58.1% of theory).

Hydrolysis with NH 3 in an autoclave gave nicotinic acid in a yield of 87.9% of theory.

Example 9:

For the feed gas containing 2-methyl-5-vinylpyridine (2-MVP), the catalyst (100 cm ³ ) shown in Example 1 was used. The catalyst temperature was 400 ° C. The feed rate was: 113.4 g | -1h -1 of 2-MVP, 2095 l -1 of air, 227 gH h -1 NH 3 and 750 gH h -1 H 2 O. After 5 hours, 57 g of 2-MVP were converted to give 23.4 g of 2,5-dicyanopyridine (37.9% of theory) and 24.4 g of 3-cyanopyridine (48.9% of theory).

Hydrolysis with NH 3 in an autoclave gave nicotinic acid in a yield of 86.3% of theory.

Example 10

The catalyst of Example 1 (710 mL) was charged to a stainless steel tubular reactor (21 mm ID, 3 m length). A gaseous mixture of reactants consisting of

3-methylpyridine (3-MP), air, ammonia and water for 1350 hours at 385 DEG C. and with a supply rate which varied between 100 and 150 GL ¹ h ¹ 3-MP. The molar ratio of 3-MP: air: ammonia: water feed varied between 1: 5.2: 10: 13 and 1: 5.2: 16: 15. 107 kg of 3-MP was converted to 108 kg

3-cyanopyridine. The conversion was 97%, the molar yield was 91% and the selectivity 93.5%.

Example 11:

The TIQ O _x was prepared according to example a), catalyst preparation, but with the difference that the tablets was carried out by heating at 850 C for 2 hours. 140 cm @ 3 of this activated catalyst were charged to the tubular reactor of Example 1. A gaseous mixture of 2-methyl-5-ethylpyridine, air, ammonia and water vapor was passed through the catalyst bed at 375 ° C. The molar ratio in the feed was:

MEP: air (O 2): NH 3: H 2 O = 1: 34: 10: 41. After 5 hours, 53.2 g of MEP was converted to give 22.8 g of 2,5-dicyanopyridine (40.2% of theory) and 22.5 g of 3-cyanopyridine (39.7% of theory).

Hydrolysis with KOH gave nicotinic acid in a yield of 90.2% of theory.

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Claims (14)

PATENT CLAIMS A method for producing a catalyst mixture of formula V _and TibZr _c O _x where a is 1b is 7.5 to 8 c is 0 to 0.5 x is the number of oxygen atoms necessary to meet the valency claims of the elements present by co-precipitation of solution V ⁵⁺ and the Ti ⁴⁺ - and optionally Zr ⁴⁺ compounds in water with a solution of ammonia in water and subsequent drying of the precipitate so formed and heat treatment and bringing the catalyst mixture into a suitable catalytic form. Method according to claim 1, characterized in that the precipitate formed is either first dried in an air stream at a temperature between 120 ° C and 140 ° C or is directly exposed to heat at temperatures between 360 ° C and 400 ° C, then is formed into a suitable catalytic form and finally exposed to heat at a temperature between 740 ° C and 850 ° C. Catalytic composition, characterized in that it can be obtained by a production process according to claim 1 or 2. Catalytic composition according to claim 3, characterized in that it is defined by the formula V Tig O _x , where x has been defined above. 5. The catalytic composition according to claim 3, characterized in that it is of the formula V T17 5 ZRG, 5 _x H wherein x is as defined above. Catalytic mixture according to claim 3, characterized in that it is defined by the formula V T17 5 ZrQj25 Οχ. where x is as defined above. A process for the preparation of cyanopyridines by oxidative ammonolysis - alkylpyridines, characterized in that the feed gas composed of alkylpyridine, oxygen-containing gas, ammonia and water vapor is passed through the precipitated catalyst mixture prepared according to claim 1 at a temperature between 330 ° C and 440 ° C. A process according to claim 7, characterized in that the catalyst mixture according to claim 4 is used. A process according to claim 7, characterized in that the catalyst mixture according to claim 5 is used. Process according to Claim 7, characterized in that the catalyst mixture according to Claim 6 is used. The process according to claims 7 to 10, wherein the alkylpyridine is selected from the group consisting of 3-methylpyridine, 3-ethylpyridine, 2-methyl-5-ethylpyridine, 2,5-dimethylpyridine and 2-methyl-5-vinylpyridine. Process according to claim 11, characterized in that 3-methylpyridine or 2-methyl-5-ethylpyridine is used. A process according to claims 7 to 12 for the production of 3-cyanopyridine by oxidative ammonolysis of 3-methylpyridine, characterized in that the feed of gaseous reactants of 3-methylpyridine, oxygen-containing gas (calculated on O2), ammonia and water vapor is : 7: 3: 3 to 1: 40: 10: 45 leads through the catalyst. A process according to claims 7 to 12 for the preparation of 3-cyanopyridine by oxidative ammonolysis of 2-methyl-5-ethylpyridine, characterized in that the supply of gaseous reactants of 2-methyl-5-ethylpyridine, oxygen-containing gas (calculated on O2), ammonia and water vapor in a molar ratio of 1: 15: 5: 20 to 1: 70: 40: 140 is passed through the catalyst.