Stability of silicon carbide membrane prepared from polymer precursor in steam

Takeyama, Akinori; Sugimoto, Masaki; Yoshikawa, Masahito

Precursor-derived silicon carbide (SiC) membrane has been a promising candidate as a membrane for hydrogen separation in harsh condition. In this report, SiC membrane was exposed to steam and its gas permeances were measured. Polymer precursor, polycarbosilane (PCS) film was coated on a porous support.Subsequently, it was cured and cross-linked by an electron beam irradiation in helium atmosphere followed by the pyrolysis at 973 K or 1073 K. A series of preparation procedure was repeated three times to layer SiC film. Prepared membrane was exposed to steam at 773 K for 10 hours. Water vapor pressure was about 47 kPa. H permeance of as-prepared membrane prepared via pyrolysis at 1073 K followed Arrhenius plot against the reciprocal temperature. This meanes H permeated through the membrane by molecular sieving mechanism. H permeance still followed Arrhenius plot after the exposure to steam. H permeance of as-prepared membrane prepared via pyrolysis at 973 K also followed Arrhenius plot. However, the membrane was subject to oxidation by steam, consequently large sized pores for Knudsen diffufion of H were formed in the membrane after the exposure.