Process for obtaining isobutylene of a purity higher than 99.5 weight percent

摘要

An improved process for recovering isobutylene contained in a mixture of hydrocarbons having four carbon atoms by selective extraction with an aqueous solution of sulfuric acid of a concentration of about 50 wt. % followed by separating the isobutylene-rich sulfuric acid extract by a first flash distillation of the extract and by a second physical separation of the isobutylene-enriched extract from said flashing step (which the latter physical separation is preferaby a second flash distillation at a temperature which is higher than the first and is at 75 DEG C. or less, and wherein said first flash distillation is between 10 DEG and 60 DEG C. and both distillations are preferably at a pressure between 0.5 and 1.5 bars absolute to give an isobutylene purity greater than 99.5%).