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percent aqueous acetic acid is withdrawn in a separator.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.
