Verfahren zur Herstellung von Maleinsaeureimid

摘要

Maleic acid imide is prepared by reacting maleic anhydride and ammonia in the gaseous phase while passing them over a dehydration catalyst. The molar ratio of ammonia to maleic anhydride is suitably 1:1.3 to 1:20 and the reaction may be carried out in the presence of a gaseous diluent such as nitrogen, air or a suitable hydrocarbon. The gaseous products of a maleic anhydride synthesis may be used instead of pure maleic anhydride. The reaction temperature is suitably 100-400 DEG C. with a contact time preferably of 0.01-2 seconds. The catalyst may comprise an oxide of Groups III to VII of the Periodic Table, e.g. aluminium oxide, or a phosphoric or polyphosphoric acid or sulphuric acid or a salt of these acids or a silicate or a mixture of these. The catalyst may be supported on a carrier such as carbon or silicon carbide.