Study On Gas Separation Process For Hydrogen Recovery Using Hollow Fiber Composite Membrane

Hydrogen recovery process from refinery dry gas based on hollow fiber composite membranes is one of the crucial and effective methods. In this study, hydrogen recovery process from the mixing gas of hydrogen, nitrogen and methane, which was simulated to the refinery dry gas, was investigated. Then, the mass transfer mechanism of gases through the composite membrane was developed.Firstly, the silicone rubber / polysulfone hollow fiber composite membranes were prepared by dip-coating method. Some penetrating behaviors of hydrogen through the composite membranes were discussed. The structure of silicone rubber, polysulfone membrane and hollow fiber composite membranes was analyzed by SEM and IR method.Secondly, the effects of polysulfone substrate layer and the silicone rubber coating layer on preparation process of composite membranes were investigated. The effects of some factors, which are different structures of polysulfone substrate layer, the temperature of heat treatment, the time of heat treatment, the number of coating and the PDMS, catalyst and cross-linker concentration, on gas separation performance of composite membranes also were discussed. The suitable formula and operation conditions for preparing the composite membrane were found.Lastly, a resistances-in-series model based on the Henis-Tripodi's model and the theory of the boundary layer for gas separation in composite membranes was presented, in which the resistance of the boundary layer and the resistance of membrane have been taken into account at the first time. Then the influences of feed flow rate, feed pressure, and the partial pressure of hydrogen in permeate gas on gas permeability and selectivity of hollow fiber composite membranes have been considered and analyzed.