Membrane integration process for butenes production

Butenes are intermediates in the petrochemical industry and iso-butene is the most important isomers because of used for many syntheses, for instance, MTBE production. Catalytic or thermal as well steam cracking are important processes in the commercial production of butenes, and so iso-butene, are always obtained as by-product. The product of this system is conventionally fed in complex separation units with cryogenic towers for separation of methane, ethane and ethylene, propane and propene. The butenes isomers are than fed in absorption process with high recovery of butenes. In this work, a membrane system is proposed for production and recovery of butenes [1]. The dehydroisomerization of n-butane is the reaction for producing iso-butene. The reaction takes place in a membrane reactor with a Pd/Ag alloys membrane where the hydrogen is removed by reaction side [2]. Afterwards the retentate and permeate post-processing is analyzed by proposing membrane separation units for butenes concentration and recovery. The retentate stream of the membrane reactor is firstly fed to membrane unit to remove the hydrogen and light hydrocarbons such as methane and ethylene. A glassy membrane used for this purpose allows the hydrocarbons recovery in retentate side at a high pressure. The hydrocarbon enriched stream then fed another membrane gas separation unit with a rubbery and mixed matrix membranes for separation of olefins and paraffins. Four different process schemes were developed the analysis of integrated systems showed a high yield of butenes with respect to the other reaction products with high butenes recovery. It was possible to recovery 80% of the total butenes produced at 75% molar concentration.