Continuous production of ethanol and plural stage distillation of the same

A process for the continuous production of ethanol via the carbonylation of methanol, which comprises

• (a) carbonylating methanol with carbon monoxide in a reactor R, in the presence of a carbonyl complex of a metal of group VIII of the periodic table which complex is dispersed in the liquid reaction medium, and in the presence of a halogen compound as activator;
• (b) separating, in a distillation column D1, the reactor discharge, which essentially consists of methyl acetate, methanol, acetic acid, water and small quantities of dimethyl ether, an organo-halogen compound and the catalyst, into a top fraction comprising methyl acetate, methanol, dimethyl ether and the organo-halogen compound, and into a bottom fraction comprising water, small quantities of acetic acid and the catalyst, the residence time of the discharge in column D1 being so adjusted that the bulk of the acetic acid reacts with the methanol present to give methyl acetate;
• (c) separating the top fraction from D1, in a distillation column D2, into a top fraction comprising small quantities of methyl acetate, methanol, dimethyl ether and the organo-halogen compound, and a bottom fraction comprising methyl acetate and methanol and recycling the top fraction to reactor R;
• (d) distilling off, via the top distillation column D3, the greater part of the water from the bottom fraction from D1 and removing this water from circulation, and recycling to reactor R the bottom fraction consisting of small quantities of water, acetic acid and the catalyst;
• (e) using hydrogen to hydrogenate, in a hydrogenation reaction H, the bottom fraction from D2, to give a mixture of methanol and ethanol, and
• (f) separating the mixture into ethanol and methanol in a distillation column D4, and recycling the methanol to reactor R.