Gas permeation Property of Silicon Carbide Membrane Synthesized by Counter Diffusion Chemical Vapor Deposition

An amorphous silicon carbide (SiC) membrane with H2 permeance of 1.2E-7 mol･m-2･s-1･Pa-1 and excellent H2/CO2 selectivity of 2600 at 673 K was successfully synthesized on a Ni-gamma-alumina-coated alpha-alumina porous support by counter diffusion chemical vapor deposition (CDCVD) using silacycrobutane (SCB) at 788 K. The dominant permeation mechanism for He and H2 in the temperature range 323-673 K was activated diffusion. The SiC active layer was formed in Ni-gamma-Al2O3 intermediate layer. The thermal expansion coefficients mismatch between SiC active layer and Ni-gamma-Al2O3-coated alpha-Al2O3 porous support was eased by the low decomposition temperature of SiC source and membrane structure.