GB528987A - Improvements in or relating to the manufacture of dimethylamine - Google Patents

Abstract

528,987. Catalytic agents. DU PONT DE NEMOURS & CO., E. I., and ARNOLD, H. R. May 18, 1939, No. 14884. [Class 1 (i)] [Also in Group IV] Dimethylamine is produced by passing over a dehydrating catalyst comprising basic aluminium phosphate at 250-550‹ C. a vapour or vapour mixture capable of forming dimethylamine, such as methanol and ammonia, methylamine or trimethylamine or methylamine above or mixed with trimethylamine. In examples (1) aluminium sulphate solution is treated with a solution of disodium phosphate and sodium carbonate and the washed and dried precipitate is mixed with graphite, tableted and calcined at 450‹ C. ; methanol and ammonia are passed over this catalyst at 445‹ C., the product being mostly di- and tri-methylamine; by contrast, if a normal aluminium phosphate catalyst in which the phosphate is precipitated from aluminium nitrate by ammonium or sodium phosphate and adding ammonia to neutralize the mixture, the product is mostly methylamine, with no demethylamine ; (2) a mixture of ammonia methanol methylamine and trimethylamine is passed over the basic aluminium phosphate catalyst employed in Example 1 at 450‹ C., the product being mostly di- and tri-methylamine. Basic aluminium phosphate may also be made by precipitating an aluminium salt with excess of sodium phosphate or digesting normal aluminium phosphate with ammonia or treating a solution of aluminium phosphate in hydrochloride or other mineral acid with ammonia. Specification 355,867 is referred to.