Molecular sieve SiC-based membrane for hydrogen separation produced by radiation curing of preceramic polymers

Polycarbosilane and its blend with polyvinylsilane of 20 wt% were used as precursor polymers to produce silicon carbide (SiC)-based membranes for gas separation. Preceramic polymers were spin coated onto porous γ-alumina substrate and crosslinked with oxygen by irradiation method. It was found that the blend undergoes higher oxidation than pure PCS due to plasticizing effect of PVS and faster oxidation of PVS itself. Subsequent pyrolysis at 1123 K converted the polymer film into inorganic material. Hydrogen and nitrogen gas permeation experiments revealed temperature activated gas transport process with temperature dependent H2 permeance of 10−10 to 10−8 mol s−1 m−2 Pa−1 order. Excellent H2/N2 perm-selectivity was achieved of nearly 150 and over 250 at 523 K for PCS and PCS/PVS blend derived membranes, respectively. The permeation was governed by a molecular sieving mechanism.