Process for the preparation of acetic acid

Claim 1

A process for the preparation of acetic acid by catalytic conversion of a synthesis gas being rich in hydrogen and carbon monoxide, comprising steps of: (i) introducing a stream of the synthesis gas into a first reaction step at a predetermined pressure and temperature and reacting the synthesis gas in the presence of a catalyst being active in formation of methanol and dehydration of methanol, so as to obtain a gaseous process phase containing methanol, dimethyl ether, and water; (ii) cooling the gaseous process phase of step (i) and obtaining a liquid phase with the methanol, dimethyl ether and water and a gaseous phase comprising carbon dioxide and residual amounts of dimethyl ether; (iii) introducing the liquid phase formed in step (ii) into a second reaction step at a predetermined pressure and temperature and adding a predetermined amount of carbon monoxide; and (iv) carbonylating methanol and dimethyl ether in the liquid phase with carbon monoxide by contact with a catalyst being active in the carbonylation of alcohols and ethers with carbon monoxide; and (v) recovering from effluent of step (iv) a product stream mainly consisting of the acetic acid product.