SEPARATION OF TERTIARY BUTYL ALCOHOL FROM DIISOBUTYLENE

摘要

A process for the separation of diisobutylene from tertiary butyl alcohol utilizing pressure swing azeotropic distillation to achieve the desired separation. The pressure swing azeotropic distillation takes advantage of the fact that different azeotropes are formed at different pressures. Isobutylene in C4 streams is oligomerized in the presence of tertiary butyl alcohol to produce the diisobutylene. Tertiary butyl alcohol is present in the dimerization because it improves the selectivity to the dimer (diisobutylene) by suppressing further reaction to the trimer or higher. The diisobutylene is separated from the tertiary butyl alcohol utilizing two distillation columns (20, 30). The first distillation is operated at a higher pressure than the second such that the minimum boiling azeotropes of tertiary butyl alcohol and diisobutylene have different concentrations of tertiary butyl alcohol. Diisobutylene is removed as bottoms (107) from the first distillation column and unreacted C4's are removed as overheads (105) at 60-130 psig . A side draw (106) containing the minimum boiling azeotrope is fed to the second distillation column (30), operated at 0-45 psig where a second minimum boiling azeotrope is formed having a lower tertiary butyl alcohol concentration. The tertiary butyl alcohol is recovered as bottoms (109) and recycled to the reactor (10). The second minimum boiling azeotrope is removed as overheads (108) and recycled to the first distillation column (20).