Title of Invention

AN IMPROVED PROCESS FOR THE PREPARATION OF ACETONITRILE

Abstract

This invention relates to an improved process for the preparation of acetonitrile which comprises passing a feed consisting of etanol, ammonia, water and air or oxygen gas with feed rate in the range of 30 cc per minute to 100 cc per minute over a vanadium-silico-alumino-phosphate catalyst (VSAPO) such as herein described at a temperature in the range of 300-450 C and weight hourly space velocity of liquid products in the range of 0.24 to 1.0 per hour and recovering the acetonitrile by conventional methods.

Full Text

This invention relates to an improved process for the preparation of acetonitrile. This invention particularly relates to an improved process for the preparation of acetonitrile from ethanol over vanadium silico - alumino - phosphate catalysts via ammoxidation. According to the process of the present invention or ethanol as reactant with ammonia and air in the presence of a catalyst selected from crystalline , porous vanadium silico-aluminophosphates(VSAPO). The process of preparing the above catalyst has been described and claimed in our copending application number 963/DE1/95. In the presently known process, acetonitrile can be produced from amination of acetic acid followed by dehydration or dehydrogenation of ethylamine. The conventional catalysts have been amorphous in nature and not shape selective catalysts. These catalysts have been employed in mostly fixed bed reactors. The following patents have discussed the preparation of nitriles of present interest, e.g. Eur.Pat; Appl. EP 37173 (1981), US Patent 4876348 (1989),US Patent 4603 207 (1986), Eur. Pat 0037123A1 (1981), Brit. Patent 77746 (1957), Ger. (East) DDPatent 241903 (1985), US Patent 3981879 (1976), US Patent 2839535 (1958), US Patent 2510605 (1950), US Patent 3981879 (1976). In these inventions the yield of nitrile may or may not be highly selective. Particularly high-boiling products, CO,CO2 were formed, due to the amorphous nature of the catalysts. The high-boling products create environmental and disposal problems. The object of the present invention is to provide an improved process for the preparation of nitriles employing porous active catalytic materials. The other objective of the invention is to provide a process for the preparation of nitriles wherein the formation of CO, CO2 and high-boiling products are minimized. The present invention provides >90% yield of acetonitrile from ethanol ammoxidation in one step with very high selectivity over VSAPO catalysts at a temperature in the range of 350 to 450° C and weight hourly space velocity in the range of 0.25 to 1.0 per hour. Accordingly, the present invention provides an improved process for the preparation of acetonitrile which comprises passing a feed consisting of ethanol, ammonia, water and air or oxygen gas with feed rate in the range of 30 cc per minute to 100 cc per minute over a vanadium-silico - alumino- phosphate catalyst (VSAPO) such as herein described at a temperature in the range of 300-450°C and weight hourly space velocity of liquid products in the range of 0.25 to 1.0 per hour and recovering the acetonitrile by conventional methods. The molar ratio of ethanol and ammonia may be in the range of 1:1 to 1:20. The feed ratio air or oxygen is 30 cc per minute preferably. The catalysts are prepared in general in the following way. A12(SO4)3, H3PO4/ Na2SiO3,with or without NaCI,V2O5 and tetrapro-pylammoniurn bromide (TPA) or tetrabutylammonium bromide (TEA) used as a template, are mixed in distilled water in the pH range of 7.0 to 12.0. The slurry is mixed for at least 2 hrs at room temperature with constant stirring and the pH is adjusted by aqueous ammonia. The slurry was put into an autoclave for auto-calving under autogeneous pressure in the temperature range of 150 to 220° C.for 24 hrs to 80 hrs till complete crystallization was achieved. The mixture was filtered and washed with distilled water.The solid catalyst was dried in oven at 120° C over night. The organic template was removed by the activation of the catalyst at 500-550° C for 5-15 hrs. Then the calcined material was modified by promoters like Sb203 or oxides of the elements active as promoters in the respective reactions. Basically in alumino-phosphate molecular sieves the AI:P atomic ratio is 1:1. The above said reactions were carried out in a tubular,down-flow, pyrex reactor with 20 mm internal diameter. The reaction mixture was fed from top using syringe pump (Sage Instruments,USA). The product was cooled by using ice-cooled water and collected at the bottom. The required number of ice-cooled traps were used to collect the total amount of products. The products were analysed by using SE-30 (5%) and OV-17 columns. The analysis was confirmed by mass spectra and GC-mass. The reaction of ethanol with ammonia in the presence of air (or oxygen) was carried out over VSAPO (TPA), VSAPO(TBA), VSAPO-37. The temperature was varied from 250 to 420° C. The highest yield of acetonitrile obtained was >83.0 wt% over VSAPO(TPA) at 350° C via ammoxidation in one step. The following examples are given to illustrate the process of the present invention,however these should not be construed to limit the scope of invention. EXAMPLE - 1 0.78 gm of Ethanol, 1.0 gm of water per hour,0.228 gm( 30 cc per min)of ammonia and 3 0.0 cc per min air over VSAPO(TPA) at 350° C and 0.5 hr-1 weight hourly space velocity of liquid feed. The ethanol to ammonia mole ratio was 1:5. The one step ammoxidation of ethanol was highly selective. No deactivation was observed for more than 6 hrs time on stream. The template TPA (tetra propyl ammonium bromide) was removed before the rection. The yield of acetonitrile was >83.0 wt% based on ethanol at 100 wt% conversion of ethanol. EXAMPLE - 2 0.7 8 gm of Ethanol, 1.0 gm of water per hour,0.22 8 gm( 3 0 cc per min) of ammonia and 30.0 cc per min air over VSAPO(TBA) at 350° C and 0.5 hr"1 weight hourly space velocity of liquid feed. The ethanol to ammonia mole ratio was 1:5. The one step ammoxidation of ethanol was highly selective. No deactivation was observed for more than 6 hrs time on stream. The template TBA (tetra butyl ammonium bromide) was removed before the rection. The yield of acetonitrile was 20 wt% conversion of ethanol. EXAMPLE - 3 0.78 gm of Ethanol, 1.0 gm of water per hour,0.228 gm( 30 cc per min)of ammonia and 30.0 cc per min air over VSAPO-37 at 350° C and 0.5 hr weight hourly space velocity of liquid feed. The ethanol to ammonia mole ratio was 1:5. The one step ammoxidation of ethanol was highly selective. No deactivation was observed for more than 6 hrs time on stream. The templates TPA (tetra propyl ammonium bromide) and TMA (tetramethyl ammonium bromide were removed before the rection. The yield of acetonitrile was conversion of ethanol. We claim : 1. An improved process for the preparation of acetonitrile which comprises passing a feed consisting of ethanol, ammonia, water and air or oxygen gas with feed rate in the range of 30 cc per minute to 100 cc per minute over a vanadium-silico - alumino- phosphate catalyst (VSAPO) such as herein described at a temperature in the range of 300-450°C and weight hourly space velocity of liquid products in the range of 0.25 to 1.0 per hour and recovering the acetonitrile by conventional methods. 2. A process as claimed in claim 1 wherein the molar ratio of ethanol and ammonia ranges from 1:1 to 1:20. 3. A process as claimed in claims 1 and 2 wherein the feed contains either air or oxygen gas with feed rate of 30 cc per minute preferably. 4. An improved process for the preparation of acetonitrile substantially as herein described with reference to the examples.

Documents:

1463-del-1995-abstract.pdf

1463-del-1995-claims.pdf

1463-del-1995-correspondence-others.pdf

1463-del-1995-correspondence-po.pdf

1463-del-1995-description (complete).pdf

1463-del-1995-form-1.pdf

1463-del-1995-form-2.pdf

1463-del-1995-form-4.pdf

1463-del-1995-form-5.pdf

1463-del-1995-form-6.pdf

1463-del-1995-form-9.pdf