GB852166A - Removal of sulfur contaminants from hydrocarbon stream - Google Patents

Abstract

Hydrocarbon streams containing C4-C6 normal alkenes and isoalkenes and contaminated with sulphur are purified by contacting with 60-70 weight per cent sulphuric acid at 50-120 DEG F. and 15-125 p.s.i.g. to dissolve isoalkenes and convert sulphur contaminants to higher boiling compounds and distilling the normal alkene containing product free of isoalkene to separate it from the higher boiling sulphur contaminants. The process is particularly useful to obtain n-butylenes free of isobutylene and sulphur contaminants for conversion to secondary butyl alcohol by subsequently dissolving in sulphuric acid and hydrolysing. Suitable starting materials are C4 olefine refinery streams obtained by thermal, catalytic or steam cracking of hydrocarbon oils and containing 40-60% butane, 7-20% isobutylene and 20-42% n-butylenes with small amounts of C3 and C5 hydrocarbons and contaminated with sulphur and sulphur compounds. Such a stream may be first washed with 12-17 DEG B<\>ae aqueous caustic soda for a preliminary sulphur removal. The amount of acid used may be such that the volume ratio of hydrocarbon to acid is from 5 to 20:1. The n-butylene obtained may be dissolved in 70-80 weight per cent sulphuric acid using 1-10 volumes of hydrocarbon per volume of acid at 80-135 DEG F. and 15-125 p.s.i.g. The extract formed is contacted with water and/or steam at 0-100 p.s.i.g. and 200-300 DEG F. to obtain secondary butyl alcohol.