Ag+ contained complex membrane for the separation of C4 olefin/paraffin mixture

The C₄ olefin/paraffin mixture was separated by means of the PE modified reversible complexing membrane, polyethylene-g-acrylic acid-Ag₊(PE-g-AA-Ag₊). The olefin could be transported to the other side of the membrane by silver facilitating phenomenon owing to the formation of (Ag-olefin)₊ complex. The SEM-EDX spectrum showed a homogeneous silver ion distribution across the dense complex membrane's cross-section at higher than about 60% grafting. The gas permeation properties measured by a gas chromatographic method implied a silver ions facilitating effect towards olefin. At 30°C and 111.7% grafting, the complex membrane exhibited a trans-2-butene/isobutane selectivity of 12.5 and a cis-2-butene/isobutane selectivity of 9.2. The permeation activation energy of the C₄ olefins became lower than that of C₄ paraffin as a result of the silver ions facilitated effect. The cis-2-butene has a significant higher complex equilibrium constant than that of the trans-2-butene in complexing with the complex membrane.