Separating hydrogen and carbon dioxide from syngas is a necessary step for many industrial processes. Membrane separations are an attractive solution as they can operate at process temperatures (200-500 °C) and operate with a simple process. Pure thermally stable (up to 600 °C) clinoptilolite zeolite was mixed with a Portland cement matrix, pressed, and cured to prepare composite membranes. Such systems offer scalable, thermally stable, and low cost membranes for H 2 and CO 2 separation from

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... gas. Pure cement membranes demonstrated CO 2 impermeability. Single gas permeation measurement of H 2 and CO 2 was conducted and demonstrated high H 2 /CO 2 selectivities up to 115 with permeances on the order of 10 -9 mol/m 2 ·Pa·s for the composite membranes. The gas diffusion tests firmly exhibited molecular sieving toward H 2 and CO 2 . These results suggest that cost-effective natural zeolites combined with ordinary Portland cement are capable of selective separation of H 2 and encourage future development of this concept.