Distillation of acrylonitrile from aqueous solutions maintained at about ph3

Claim 2

IN A CATALYTIC PROCESS FOR PRODUCING ACRYLONITRILE BY REACTING AMMONIA, AIR AND PROPYLENE TO PRODUCE A HOT GASEOUS REACTION MIXTURE CONSISTING ESSENTIALLY OF SMALL AMOUNTS OF ORGANIC REACTION PRODUCTS COMPRISING ACRYLONITRILE, ACETONITRILE, HYDROCYANIC ACID, CYANOHYDRINS AND UNREACTED AMMONIA, COOLING THE GASEOUS REACTION OIXTURE IN DIRECT CONTACT WITH MINERAL ACID CONTAINING COOLING WATER, WHEREBY AMMONIA IS REMOVED FROM THE REACTION GASES AND AN AQUEOUS AMMONIUM SALT SOLUTION IS FORMED IN WHICH MINOR PARTS OF ABOUT 3% OF THE ORGANIC REACTION PRODUCTS ARE DISSOLVED, THE IMPROVEMENT COMPRISING RECOVERING SAID ORGANIC REACTION PRODUCT FROM SAID AQUEOUS AMMONIUM SALT SOLUTION INCLUDING THE STEPS OF: A. ADJUSTING THE PH OF THE AQUEOUS AMMONIUM SALT SOLUTION CONTAINING THE DISSOLVED ORGANIC REACTION PRODUCTS TO A VALUE OF ABOUT 3, B. FEEDING SAID AQUEOUS AMMONIUM SALT SOLUTION CONTAINING THE DISSOLVED ORGAIC REACTION PRODUCTS TO A DISTILLATION COLUMN OPERATING UNDER REDUCED PRESSURE WHILE MAINTAINING THE BOTTOM TEMPERATURE OF SAID DISTILLATION BETWEN 40* AND 100*C. TO SEPARATE THE DISSOLVED ORGANIC REACTION PRODUCTS FROM THE SALT SOLUTION AND C.RECOVERING THE ACRYLONITRILE PRESENT IN THE ORGANIC REACTION PRODUCTS THUS REMOVED FROM THE AQUEOUS AMMONIUM SALT SOLUTION.

Claim 3

The process of claim 1 wherein said bottom temperature is maintained between about 40.degree. C. and about 75.degree. C.

Claim 4

In a catalytic process for producing acrylonitrile by reacting ammonia, air and propylene to produce a hot gaseous reaction mixture consisting essentially of small amounts of organic reaction products comprising acrylonitrile, acetonitrile, hydrocyanic acid, cyanohydrins and unreacted ammonia, cooling the gaseous reaction mixture in direct contact with mineral acid containing cooling water, whereby ammonia is removed from the reaction gases and an aqueous ammonium salt solution is formed in which minor parts of about 3 percent of the organic reaction products are dissolved, the improvement comprising recovering said organic reaction products from said aqueous ammonium salt solution including the steps of: a. adjusting the pH of the aqueous ammonium salt solution containing the dissolved organic reaction products to a value of about 3 by the addition of a strong mineral acid, b. feeding said aqueous ammonium salt solution containing the dissolved organic reaction products to a distillation column operating under a reduced pressure of about 50-275 mm Hg while maintaining the bottom temperature of said distillation column between 40.degree. and 100.degree.C. to separate the dissolved organic reaction products from the salt solution and c. recovering the acrylonitrile present in the organic reaction products thus removed from the aqueous ammonium salt solution.

Claim 5

In a catalytic process for producing acrylonitrile by reacting ammonia, air and propylene to produce a hot gaseous reaction mixture consisting essentially of small amounts of organic reaction products comprising acrylonitrile, acetonitrile, hydrocyanic acid, cyanohydrins and unreacted ammonia, cooling the gaseous reaction mixture in direct contact with mineral acid containing cooling water, whereby ammonia is removed from the reaction gases and an aqueous ammonium salt solution is formed in which minor parts of about 3 percent of the organic reaction products are dissolved, the improvement comprising recovering said organic reaction products from said aqueous ammonium salt solution including the steps of: a. adjusting the pH of the aqueous ammonium salt solution containing the dissolved organic reaction products to a value of about 3 by the addition of a strong mineral acid, b. feeding said aqueous ammonium salt solution containing the dissolved organic reaction products to a distillation column operating under a reduced pressure of about 50-275 mm Hg while maintaining the bottom temperature of said distillation column between 40.degree. and 100.degree.C. to separate the dissolved organic reaction products from the salt solution and c. recovering the acrylonitrile present in the organic reaction products thus removed from the aqueous ammonium salt solution.

Claim 6

The process of claim 3 wherein the strong mineral acid is sulfuric acid or phosphoric acid.

Claim 7

In a catalytic process for producing acrylonitrile by reacting ammonia, air and propylene to produce a hot gaseous reaction mixture consisting essentially of small amounts of organic reaction products comprising acrylonitrile, acetonitrile, hydrocyanic acid, cyanohydrins and unreacted ammonia, cooling the gaseous reaction mixture in direct contact with mineral acid containing cooling water, whereby ammonia is removed from the reaction gases and an aqueous ammonium salt solution is formed in which minor parts of about 3 percent of the organic reaction products are dissolved, the improvement comprising recovering said organic reaction products from said aqueous ammonium salt solution including the steps of: a. adjusting the pH of the aqueous ammonium salt solution containing the dissolved organic reaction products to a value of about 3, b. feeding said aqueous ammonium salt solution containing the dissolved organic reaction products to a distillation column to separate the dissolved organic reaction products from the salt solution and c. recovering the acrylonitrile present in the organic reaction products thus removed from the aqueous ammonium salt solution.

Claim 8

In a catalytic process for producing acrylonitrile by reacting ammonia, air and propylene to produce a hot gaseous reaction mixture consisting essentially of small amounts of organic reaction products comprising acrylonitrile, acetonitrile, hydrocyanic acid, cyanohydrins and unreacted ammonia, cooling the gaseous reaction mixture in direct contact with mineral acid containing cooling water, whereby ammonia is removed from the reaction gases and an aqueous ammonium salt solution is formed in which minor parts of about 3 percent of the organic reaction products are dissolved, the improvement comprising recovering said organic reaction products from said aqueous ammonium salt solution including the steps of: a. adjusting the pH of the aqueous ammonium salt solution containing the dissolved organic reaction products to a value of about 3, b. feeding said aqueous ammonium salt solution containing the dissolved organic reaction products to a distillation column to separate the dissolved organic reaction products from the salt solution and c. recovering the acrylonitrile present in the organic reaction products thus removed from the aqueous ammonium salt solution.