Preparation and gas transport properties of dual-layer polysulfone membranes for high pressure CO₂ removal from natural gas

Permeability, sorption, and plasticization behaviors of dual-layer composite membrane were studied. Polysulfone containing 10.7 wt % glycerol as additive was used for preparing a microporous membrane support. A thin top selective layer was prepared using diethylene glycol dimethyl ether as casting solvent. The overall performance of the membrane was evaluated using Scanning Electron Microscopy, and permeation and sorption tests at pressure up to 50 bar. The prepared membrane displayed high permeability at low pressure which gradually decreased with increase in pressure. Permeability of CO₂ was determined to be 84.97 Barrer at 2 bar. Membrane did not show any plasticization tendency up to the experimental pressure of 40 bar. Plasticization pressure and permeability at plasticization pressure were estimated to be 41.07 bar and 6.03 Barrer, respectively. The improved performance of the membrane is associated to the synergistic properties of the two layers prepared from different formulations of the same polymer. Thus, the dual-layer flat sheet configuration displayed a potential in high pressure CO₂ removal from natural gas.