Pressure swing membrane absorption process for shifted syngas separation: Modeling vs. experiments for pure ionic liquid

We have carried out studies for CO₂ removal from hot simulated pre-combustion shifted syngas by a pressure swing membrane absorption (PSMAB) process. In this cyclic separation process, a well-packed membrane module containing either hydrophobized porous ceramic tubules or hydrophobized polyether ether ketone (PEEK) porous hollow fibers was used to achieve non-dispersive gas absorption from a high-pressure feed gas into a stationary absorbent liquid on the module shell side during a certain part of the cycle followed by controlled desorption of the absorbed gases from the liquid in the rest of the cycle. Helium was used as a surrogate for H₂. Separation of the feed mixture containing 40.67% CO₂-He balance was done using pure ionic liquid 1-butyl-3-methylimidazolium dicyanamide ([bmim][DCA]) as the liquid absorbent. A mathematical model was developed to predict the extent of separation of the feed gas mixture into two product streams, one He-rich and the other CO₂-rich over a temperature range of 25-100°C.