Acetic Anhydride from Dimethyl Ether or Methyl Acetate

A recent Halcon patent describes technologies for converting the raw materials dimethyl ether and methyl acetate to acetic anhydride. The anhydride is formed by reacting the ether or the acetate with carbon monoxide in the presence of a catalyst system of RhCl₃•H₂O-CH₃I-picoline—chromium carbonyl. Our review examines the technology and economics of converting each of the raw materials to acetic anhydride. Economic comparisons are made with an established route that involves low pressure carbonylation of methanol to form acetic acid followed by the conversion of the acid to acetic anhydride via ketene. Our results show that the Halcon technology appears to be at least competitive with the established route.