Gas Permeation Property of Silicon Carbide Membranes Synthesized by Counter-Diffusion Chemical Vapor Deposition

An amorphous silicon carbide (SiC) membrane was synthesized by counter-diffusion chemical vapor deposition (CDCVD) using silacyclobutane (SCB) at 788 K. The SiC membrane on a Ni-γ-alumina (Al(2)O(3)) α-coated Al(2)O(3) porous support possessed a H(2) permeance of 1.2 × 10(−7) mol·m(−2)·s(−1)·Pa(−1) and an excellent H(2)/CO(2) selectivity of 2600 at 673 K. The intermittent action of H(2) reaction gas supply and vacuum inside porous support was very effective to supply source gas inside mesoporous intermediate layer. A SiC active layer was formed inside the Ni-γ-Al(2)O(3) intermediate layer. The thermal expansion coefficient mismatch between the SiC active layer and Ni-γ-Al(2)O(3)-coated α-Al(2)O(3) porous support was eased by the low decomposition temperature of the SiC source and the membrane structure.