Sorption properties of hydrogen-selective PDMS/zeolite 4A mixed matrix membrane

The present study explores the fundamental science of estimating sorption of gases in membranes comprised of inorganic porous fillers within a polymer matrix with a novel semi-empirical correlation. The sorption properties of H2, C3H8, CO2 and CH4 were determined in polydimethylsiloxane (PDMS)/zeolite 4A mixed matrix membranes (MMMs) to assess the viability of these membranes for hydrogen purification and natural gas sweetening. Zeolite filling in MMMs results an increase in solubility over neat PDMS membrane. In addition, incorporation of zeolite 4A to PDMS membrane improved H2 permeation and H2/CH4 selectivity. The results confirmed that zeolite 4A can significantly improve the separation properties of poorly H2-selective PDMS membrane from 0.7 up to 11 and this overcomes the Robeson upper-bound limitation. This improvement was explained referring the Flory–Huggins interaction parameter within MMMs.

► Sorption estimation of gases in the MMMS using semi-empirical correlation.
► Improved H2/CH4 separation performance surpassing the Robeson's trade-off curve.
► Estimation of the Flory–Huggins interaction parameter within the MMMs.
► Assessment of the MMMs for natural gas sweetening and hydrogen purification.