Continuous isobutylene-assisted aqueous extraction of methanol from methyl tertiary butyl ether

A method for the continuous purification of methyl tertiary butyl ether contaminated with isobutylene, methanol and water, which comprises:

• continuously charging an extraction feed comprising water isobutylene, methanol and methyl tertiary butyl ether to a methanol extraction zone comprising a counter-current contact tower and countercurrently contacting said extraction feed therein with water to provide an organic phase overhead raffinate comprising isobutylene, methyl tertiary butyl ether and a minor amount of water and a water phase extract comprising methanol, water and a minor amount of methyl tertiary butyl ether and stripping said extract with an isobutylene fraction in said extraction tower to remove most of said methyl tertiary butyl ether therefrom,
• continuously charging said raffinate to a methyl tertiary butyl ether purification distillation zone and separating said raffinate therein into a lighter distillation fraction comprising isobutylene and water and a heavier distillation fraction consisting essentially of methyl tertiary butyl ether;
• continuously charging said lighter distillation fraction to a decantation separation zone and separating it therein into a distillate isobutylene fraction and a water fraction;
• continuously accumulating isobutylene from said distillate isobutylene fraction in a surge drum having a capacity adequate to provide for about 12 to 36 hours of continuous operation of said counter-current contact tower,
• continuously returning distillate isobutylene from said surge drum to said counter-current contact tower at a charge point about 1 to 3 theoretical plates below the point of introduction of said extraction feed.