Extractive distillation of isopropyl alcohol with an ether solvent recovered from the initial feed

Claim 1

Process for recovering a water-free mixture of isopropyl alcohol, diisopropyl ether and, as by-products, n-propanol, acetone, hexanol and hydrocarbons, from the catalytic hydration of propylene in the gaseous phase at temperatures of 140°-170°C and pressures of 25-40 atmospheres gauge which consists essentially of: a. conducting the hydration reaction with a water-to-propylene molar ratio of 0.1 to 0.25 to produce a crude reaction product mixture containing water, isopropyl alcohol, diisopropyl ether and said by-products; b. concentrating the crude reaction product from (a) by distillation in a first column, withdrawing water as the sump product until the mixture is close to the azeotropic concentration of the isopropyl alcohol-water azeotrope; and c. extractively distilling at least a portion of the concentrated mixture from (b) in a second column withdrawing said water-free mixture as the sump product and a mixture consisting of diisopropyl ether and said by-products formed in hydration step (a) prior to steps (b) and (c) and recycling said mixture of diisopropyl ether and by-products to the top of said second column, said diisopropyl ether formed exclusively as a byproduct of the hydration reaction serving as the extracting agent for the distillation in the second column, while eliminating the need for an external source of diisopropyl ether make-up.