GB1347909A - Manufacture of nitrites - Google Patents

Abstract

1347909 Manufacture of nitrites E I DU PONT DE NEMOURS & CO 19 April 1971 [1 April 1970] 24663/71 Heading C1A Nitrites of inorganic bases are prepared by cooling a gas mixture containing nitrogen oxides, O 2 , and water vapour from a temperature above its dew point to 300-500‹ C. and quenching the produced gas mixture in a cold aqueous solution of the base. In the illustrated embodiment the gas mixture obtained by oxidation of ammonia passes via line 1 to heat exchanger 2 where its temperature is reduced from about 900‹ C. to about 400‹ C. The cooled gas then enters the column 3, below the surface of the pool of quenching liquid 7, which is at Ca 50-60‹ C., being rapidly quenched and the gas then passes up column 3, past baffles dividing the column into zones 8, which is filled with foam and gas whilst being subjected to a countercurrent flow of quenching liquid. Quench liquor is withdrawn from the foot of column 3 to maintain the depth of the pool 7 and passes to hold-up tank 14 from which it is recycled to the head of the column via pump 17 and heat exchanger 16. A portion of the product liquor is removed at 21, and fresh quench liquor added at 11. The preferred conditions for the reaction are: temperature of quench liquor less than 120‹ C. especially 50‹ C.; temperature of admission of gas mixture about 300-500‹ C.; ratio NO 2 +N 2 O 4 : NO+NO 2 +N 2 O 4 approximately less than 40%; content of nitrogen oxides in gas about 10%; and concentration of quench liquor at least 1% especially about 10%.