Abstract: Formation of butadiene-1,3 polymer during the extractive distillation of a C-4 hydrocarbon mixture to separate and purify butadiene-1,3 using a solvent composition in which an alkoxynitrile is present in a proportion of 50-99 percent by weight, is decreased through inclusion in the solvent of a synergistic combination of 2,4-dinitrophenol and phosphoric acid, each in a proportion of 0.05 to 0.5 percent by weight.

Abstract: Conjugated diolefins contaminated with relatively high levels of acetylenic impurities in a hydrocarbon feedstream are purified by a cyclic, liquid phase, predominantly catalytic cracking process which selectively removes alpha-acetylenes in a single pass. The energy requirement for removing the alpha-acetylenes in this liquid phase process are from about one-third to about one-fifth as great as that required in a comparable vapor phase process. A feedstream containing about equal weights of butadiene and mixed monoolefins and alkanes contaminated with alpha-acetylenes including vinyl acetylene and methyl acetylene, inter alia, in an amount up to about 1.0 percent by weight (% by wt) of the feedstream, is contacted in the liquid phase with a supported Group I B metal oxide catalyst in the absence of hydrogen, at a temperature in the range from about 200.degree. F. to about 260.degree. F.

Abstract: Conjugated diolefins contaminated with relatively high levels of acetylenic impurities in a hydrocarbon feedstream are purified by a cyclic, vapor phase, predominantly catalytic cracking process which selectively removes alpha-cetylenes in a single pass. A feedstream containing about equal weights of isoprene and mixed monoolefins and alkanes contaminated with alpha-acetylenes including isopropenyl acetylene inter alia, up to about 5.0 percent by weight (% by wt) of the feedstream, and a larger amount of cyclopentadiene, is contacted in the vapor phase with a supported Group I B metal oxide catalyst in the absence of hydrogen, at a temperature in the range from about 300.degree. F. to about 360.degree. F. In this narrow temperature range, the loss of diolefin is less than 1% by weight. Essentially all the cyclopentadiene (CPD) is left unconverted.