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Keywords:

  • ammonia decomposition;
  • catalytic membrane reactor;
  • silica membrane;
  • COx-free hydrogen;
  • hydrogen production

Catalytic decomposition of NH3 with H2-selective microporous silica membranes for COx-free hydrogen production was studied theoretically and experimentally. The simulation study shows that NH3 conversion, H2 yield and H2 purity increase with the Damköhler number (Da), and their improvement is affected by the effect of H2 extraction as well as NH3 and N2 permeation through the membranes. The experimental study of NH3 decomposition was carried out in a bimodal catalytic membrane reactor (BCMR), consisting of a bimodal catalytic support and a H2-selective silica layer. Catalytic membranes showed H2 permeances of 6.2–9.8 × 10−7 mol m−2 s−1 Pa−1, with H2/NH3 and H2/N2 permeance ratios of 110–200 and 200–700, respectively, at 773 K. The effect of operating conditions on membrane reactor performance with respect to NH3 conversion, H2 yield and H2 purity was investigated, and the results were in agreement with those calculated by the proposed simulation model. © 2012 American Institute of Chemical Engineers AIChE J, 59: 168–179, 2013