Acetic Anhydride

Abstract

A mixture of vapourised acetic acid and 0.25 percent triethyl phosphate is fed into a tubular reactor. Pyrolysis takes place at 7500C under a pressure of 200 mmHg. The cracking furnace exit gases containing acetic anhydride, acetic acid, ketene and water are cooled and condensed. 30-35 percent aqueous acetic acid is withdrawn in a separator. The uncondensed gases of almost pure ketene, are reacted with acetic acid in a series of scrubbers. The conversion of acetic acid is about 90 percent per pass and a selectivity of acetic anhydride based on acetic acid is about 90 percent. Acetic acid is recovered in a raw acetic anhydride column and recycled. Raw acetic anhydride is finished to remove low boilers and tars.