Title of Invention

AN IMPROVED PROCESS FOR THE PREPARATION OF ACETONITRILE

Abstract

An improved process for the preparation of acetoni- trile which comprises passing a feed consisting of ethanol, ammonia ranging from 1:1 to 1:20 water and air or oxygen gas ranging from 30 cc per minute to 100 cc per minute over a silico-alumino-phosphate catalyst (SAPO) catalyst prepared by the process 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 0.2 5 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 silico-alumi-no-phosphate catalysts via ammoxidation. According to the process of the present invention or ethanol is reacted with ammonia and air in the presence of a catalyst selected from crystalline, porous silico-aluminophosphates (SAPO). The process _pf preparing the above catalyst has been described and claimed in our copending application number 1459/Del/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 003712/.I (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, C0,C02 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 develop selective and particularly 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, C02 and high-boiling products are minimized. Accordingly, the present invention provides >90% yield of acetonitrile from ethanol ammoxidation in one step with very high selectivity over SAPO catalysts at a temperature in the range of 350 to 450 C and weight hourly space velocity in the range of 0.2 5 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 ranging from 1:1 to 1:20 water and air or oxygen gas ranging from 3 0 cc per minute to 100 cc per minute over a silico-alumino-phosphate catalyst (SAPO) catalyst prepared by the process such as herein de- o scribed 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 aceto- nitrile by conventional methods. In an embodiment of the invention molar ratio of ethanol and ammonia may be in the range of 1:1 to 1:20. The feed ratio air or oxygen may be in the range of 30 to 100 cc/hour. The catalysts are prepared in general in the following way. Al (SO ) , H PO , Na SiO , with or without 2 4 3 3 4 2 3 NaCl and tetrapropylammonium bromide (TPA) or tetrabu-tylammonium bromide (TBA) used as a template,are mixed in distilled water in the pH range of - 7.0 to 12.0. The slurry is mixed for atleast 2 hrs at room temperature with constant stirring and the pH is adjusted by aqueous ammonia. The slurry was put into an autoclave for autoclaving 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 12 0 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 aluminophosphate molecular sieves the Al:P atomic ratio is 1:1. We have substituted P partially by Si as discussed and claimed in the. copending patent number : NF 212/93. Al also may be substituted partially by Si with the corresponding variation in the atomic ratio. 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 SAPO(TPA),NaY zeolite and V-NaY. The temperature was varied from 250 to 420 C. The higest yield of acetoni-trile obtained was 99.0 wt% over SAPO(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,0.22 8 gm( 3 0 cc per min)of. ammonia and 3 0.0 cc per min air over SAPO(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 hrstime on stream. The template TPA (tetra propyl ammonium bromide) was removed before the rection. The yield of acetonitrile was EXAMPLE - 2 0.78 gm of Ethanol, 1.0 gm of water per hour,0.22 8 gm( 3 0 cc per min)of ammonia and 3 0.0 cc per min air over SAPO(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 tem- plate TBA (tetra butyl ammonium bromide) was removed before the rection. The yield of acetonitrile was EXAMPLE - 3 0.78 gm of Ethanol, 1.0 gm of water per hour,0.22 8 gm( 3 0 cc per min)of ammonia and 3 0.0 cc per min air over SAPO-37 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 templates TPA (tetra propyl ammonium bromide) and TMA (tetramethylammonium bromide ) was removed before the rection.The yield of acetonitrile was EXAMPLE - 4 0.78 gm of Ethanol, 1.0 gm of water per hour,0.22 8 gm( 3 0 cc per min)of ammonia and 3 0.0 cc per min air over SAPO(TPA) at 350 C and 0.75 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 75.8 wt% based on ethanol at 78 wt% convertion of ethanol. EXAMPLE - 5 0.78 gm of Ethanol, 1.0 gm of water per hour,0.22 8 gm( 3 0 cc per min)of ammonia and 3 0.0 cc per min air over SAPO(TPA) at 3 50 C and 0.2 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 50.2 wt% based on ethanol at 58 wt% convertion of ethanol. Advantages : 1. The process of the present invention is a one step process for the preparation of acetonitrile. 2. Yield of acetonitrile produced is very high >90%. 3. This process minimised the formation of CO, C02 and high boiling products hence elinimates the problems of disposal. WE CLAIM : 1. An improved process for the preparation of acetoni- trile which comprises passing a feed consisting of ethanol, ammonia ranging from 1:1 to 1:20 water and air or oxygen gas ranging from 3 0 cc per minute to 100 cc per minute over a silico-alumino-phosphate catalyst (SAPO) catalyst prepared by the process 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 0.2 5 to 1.0 per hour and recovering the acetonitrile by conventional methods. 2. An improved process as claimed in claim 1 wherein, the feed ratio of air or oxygen gas used is 60 cc per minute. 3. An improved process for the preparation of aceto-nitrile substantially as herein described with refer-ence to the examples.

Documents:

961-del-1995-abstract.pdf

961-del-1995-claims.pdf

961-del-1995-complete specification (granted).pdf

961-del-1995-correspondence-others.pdf

961-del-1995-correspondence-po.pdf

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

961-del-1995-form-1.pdf

961-del-1995-form-2.pdf

961-del-1995-form-4.pdf

961-del-1995-form-5.pdf

961-del-1995-form-6.pdf

961-del-1995-form-9.pdf