Multiblock copolymers containing polyether segments for separation of C4 hydrocarbons


Separation of C4 paraffins and C4 olefins from each other is an underdeveloped sector of membrane gas separation. Permeabilitieis, diffusivities and solubilities of C4 paraffins (i.e. n-butane and isobutane) and C4 olefins (i.e. cis-2-butene, trans 2-butene, 1-butene, isobutylene and 1,3-butadiene) in three commercial polymers- PEBAX 2533, PolyActive1500PEGT77PBT23 and PolyActive4000PEGT77PBT23 are reported in this study for the first time. The aim of this study is to thoroughly understand the single gas permeation mechanism of the C4 paraffins and C4 olefins through the multiblock copolymers. The cohesive energy density of the polyether segments plays a vital role to determine the permeabilities through the polymer. The selectivity of the olefin/paraffin gas pairs are largely dependent on the content of the ether oxygen of the polyether segments. But the selectivity of the paraffin gas pair and the olefin isomer gas pairs are not influenced by the ether oxygen content of the polyether segments of the multiblock copolymers.
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