Separability of carbon dioxide from methane using MFI zeolite–silica film deposited on gamma-alumina support

Silicalite-1, Na-ZSM-5 and B-ZSM-5 zeolite crystals were grown on a mesoporous silica layer to form MFI zeolite asymmetric layer for separation of CO2 from CO2/CH4 binary mixture. Silicalite-1 demonstrated the highest crystallinity followed by B-ZSM-5 and Na-ZSM-5. The cubical and rectangular MFI zeolite crystal structures exhibited random orientation. The crystals appeared to interlock and entwine with each other to form a continuously polycrystalline film covering the surface of the silica support. Results from the permeation test indicated that the selectivity and permeation flux of CO2 decreased as the temperature was increased but they increased with increase in pressure. B-ZSM-5 showed the highest CO2/CH4 selectivity of 8.17 followed by Na-ZSM-5 and silicalite-1 crystals with selectivity of 6.28 and 2.23, respectively.