Improvements in and relating to the separation of alcohols

• Main Authors: LAMB SIDNEY ARTHUR, SMITH HE NRY OWEN, NORCROSS GEOFFREY
• Format: Patent
• Language: English
• Published: 17.06.1959
• Subjects: ACYCLIC OR CARBOCYCLIC COMPOUNDS; CHEMISTRY; METALLURGY; ORGANIC CHEMISTRY

Aliphatic C3-C5 monoalcohols are obtained from the crude hydrogenated carbonylation product of a C2-C4 olefine, which product contains the alcohols together with other oxygenated compounds and a high boiling burden oil, by distilling at atmospheric or reduced pressure, removing overhead a fraction containing a high proportion of the alcohols and as bottoms the burden oil, and the overhead fraction is distilled at atmospheric pressure in the presence of a proportion of steam not exceeding 10 per cent by weight of the feedstock to this step, the feedstock being introduced at an intermediate point and preferably at least some of the steam below this point and at or near the bottom of the column, removing overhead an aqueous mixture having an organic content of not more than 30 per cent by weight of the organic content of the feed to the column and containing at least some of the desired alcohols which may be dry. The bottoms from the first step may be further distilled under reduced pressure removing as bottoms a burden oil which is used as a solvent and diluent in the carbonylation process and overhead a fraction to be discarded containing a small amount of intermediate heavy ends and desired alcohols. When ethylene is carbonylated the product comprises substantially n-propanol and the bottoms from the second step may be further purified and dried by azeotropic distillation adding benzene or trichlorethylene as entrainer. Isobutylene yields 3-methyl-butanol-1 and the bottoms from the second step may be dried by straightforward distillation taking an aqueous azeotrope overhead, from which after condensation the upper layer is returned as reflux. Starting with propylene or n-butenes-1 and -2 a mixture is obtained and the bottoms from the second step are distilled taking an aqueous azeotrope overhead to dry the alcohols, the upper layer of the condensed overhead being returned as reflux, and the bottoms product is fractionated to recover the separate alcohols.