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A silica membrane prepared by a counterdiffusion CVD method using tetramethyl orthosilicate and O 2 was applied to a steam reforming reaction of methane. This silica membrane showed hydrothermal stability for more than 80 h at 773 K under H 2 O/N 2 ) 3. The H 2 /H 2 O permeance ratio was about 290 after the hydrothermal stability test. Rh or Ni catalyst was dipped on a porous alumina substrate before chemical vapor deposition (CVD). As a result, a composite catalytic membrane of a hydrogen permselective silica layer and a catalyst layer was obtained. This catalyst composite membrane reactor was applied to steam reforming reaction to extract hydrogen. Rh catalyst showed better stability than that for Ni catalyst. Methane conversion was increased to 64.5% from the equilibrium value (31.4%) at 773 K under S/C ) 2 by the Rh-dipped membrane reactor. High conversion of methane was due to high selectivity of H 2 /H 2 O that was confirmed by the simulation evaluation.

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Development of high performance hydrogen-selective inorganic membrane has become an important requisite for the production of hydrogen, an energy carrier that could cater the ongoing energy revolution. This paper describes a novel, hybrid method to process high performance hydrogen perm-selective membranes by the rapid CVD modification of a sol-gel silica layer. The initial N 2 permeance values through a membrane were brought down by four orders of magnitude to 2.74 × 10 −10 mol m −2 s −1 Pa −1 within 5 min of CVD, while maintaining the H 2 permeance values as high as 6.43 × 10 −7 mol m −2 s −1 Pa −1 (H 2 /N 2 = 2300). It is likely that the reduction in the CVD zone thickness achieved by the presence of pre-existing sol-gel silica layer is the reason for the rapid modification of the pore structure to high performance membranes.