Polyethylene with radiation-grafted sulfonated polystyrene membranes for butane and butenes separation

• Membrane from polyethylene with radiation-grafted sulfonated polystyrene was used. • The membrane allows the selective separation of paraffins and C4 olefins mixtures. • Separation selectivity/permeability increase with rising the gas flow humidity. The possibility of paraffins and C4 olefins mixture separation on membranes made of polyethylene with radiation-grafted sulfonated polystyrene is shown. The selective separation is achieved due to the butenes and isobutene facilitated transfer in the form of a π-complex with a proton. Moreover, despite the significantly larger cross-sectional size, obstructing the transfer, isobutene molecules are also transferred much faster than butane, and the separation coefficient reaches 3.8. An unusual fact was discovered of separation selectivity and permeability increase with the separated gases flow humidity rise.