Abstract: A selective absorption process for separating C.sub.2 -C.sub.4 alkenes (in particular ethylene) from C.sub.1 -C.sub.5 alkanes with a liquid extractant comprising dissolved copper(I) compound(s), in particular dissolved Cu(I) hydrocarbonsulfonate(s), is carried out in a one-column operation, wherein an overhead product is withdrawn which contains alkene(s) at a lower concentration than the feed, a side product is withdrawn which contains alkene(s) at a higher concentration than the feed, and a bottoms stream is withdrawn which contains primarily the liquid extractant.

Abstract: An extractive distillation process for separation ethers (in particular methyl t-butyl ether or ethyl t-butyl ether), aliphatic hydrocarbons (in particular isobutane and/or isobutene) and alcohols (in particular methanol or ethanol) employs as solvent sulfolane(s) and/or dialkyl sulfone(s), or N-(.beta.-mercaptoalkyl)-2-pyrrolidone(s), or a mixture of N-alkyl-2-pyrrolidone(s) and either sulfolane(s) or glycol compound(s).