The influence of toluene (TOL) and methylcyclohexane (MCH) on the performance of dimethoxydiphenylsilane-derived silica membranes prepared by chemical vapor deposition was investigated. The presence of TOL decreased the H2 and N2 permeances. These decreases were more pronounced at higher TOL concentration and lower temperature. This was attributed to the adsorption of TOL, and permeance was largely recovered by regeneration in H2. The recovery of N2 permeance was less satisfactory than that of H2 permeance. The presence of MCH had a much smaller effect on membrane performance, though N2 permeance was mildly affected. The difference in the effects of TOL and MCH on membrane performance reflected the differing physical interactions of these molecules with the membrane. The interaction between TOL and silica was stronger and adsorption therefore more favorable, than that between MCH and silica. Thus, TOL was more difficult to remove from the membrane surface and pores.
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