PROCESSO PARA RECUPERACAO DE 1,3-BUTADIENO OU 2-METIL-1,3-BUTADIENO DE ALTA PUREZA

摘要

(I) or 2-methyl-1,3-butadiene (II) of high purity is recovered from a mixt. of 4-5C hydrocarbons by extractive distn. in 2 steps in the presence of a selective solvent. During the separation, in the solvent rectification column, of (I) or (II) and the acetylenic hydrocarbons (II) and/or the allenic hydrocarbons (III) having the same no. of C atoms, which are contained in small amt. in the tail stream leaving an extractive distillation column, the selective solvent contg. (II) and/or (III) is removed in the form of a lateral vapour phase stream from the same stage as the introduction stage of the starting materials of the solvent distillation column or from an adjacent stage, it is introduced into a heat recovery step and then recycled to the same stage as that from which it was removed from the solvent rectification column or to an adjacent stage. The process results in significant saving in heat energy without adversely affecting separation of the desired prod.