Abstract: In processes for dimerization of olefins in the presence of potassium catalysts, plugging of the catalyst bed may be avoided by purging with certain aliphatic hydrocarbons.

Abstract: A membrane separation is incorporated in a distillation cycle for efficient recovery of carbon dioxide from a stream containing natural gas along with carbon dioxide. Methane and carbon dioxide are separated from a feed stream in a first distillation to produce a process stream containing essentially methane and carbon dioxide and which is substantially free to ethane and higher molecular weight hydrocarbons. The process stream consisting essentially of methane and carbon dioxide is subjected to further distillation to produce a carbon dioxide-rich product stream and a process stream enriched in methane. The methane-enriched process stream is then passed to a membrane separation unit for separating methane and carbon dioxide and for producing a high purity methane product stream.

Abstract: By incorporating a gas permeable membrane into a hydrogen purification process at the front end of the cryogenic unit, the low purity hydrogen can be made into a high purity stream and a low purity stream. The critical pressure of the low purity stream is such that the low purity stream can be purified cryogenically without depressurization.