1,3-butadiene separation from a crude c.sub.4 stream using catalytic

Abstract

A process for separating 1,3-butadiene from a crude C.sub.4 stream containing butanes, butenes, butadienes and acetylenes has been developed. The process begins with introducing hydrogen, a solvent, and the crude C.sub.4 stream to a catalytic extractive distillation unit having a reaction zone containing a catalyst capable of hydrogenating acetylenes. Butanes and butenes, being less soluble in the solvent, are distilled in an overhead stream from the catalytic extractive distillation unit. Butadienes and acetylenes, being more soluble in the solvent, are carried with the solvent to the reaction zone located within the catalytic extractive distillation unit. In the reaction zone the acetylenes are converted to hydrogenation products. The hydrogenation products other than butadiene are separated from the butadienes by the extractive distillation occurring in the unit. The solvent and butadiene mixture is removed from the catalytic extractive distillation unit in a distillate stream. The distillate stream is then introduced to a solvent stripping column to separate by distillation a solvent bottoms stream from a butadiene overhead stream. The butadiene overhead stream is introduced to a butadiene distillation column to separate a 1,3-butadiene overhead stream from a 1,2-butadiene bottoms stream. The solvent bottoms stream may be purified and recycled to the catalytic distillation unit.