Hydrolysis of ammonia–borane catalyzed by an iron–nickel alloy on an SBA-15 support

An unsupported iron–nickel (Fe–Ni) alloy and several Fe–Ni alloy deposited on SBA-15 (Santa Barbara Amorphous-15) supports (Fe–Ni/SBA) with various Fe–Ni contents are prepared and used as catalysts in the hydrolysis of ammonia–borane (AB) for hydrogen generation. By maintaining a constant concentration of Fe–Ni in the AB aqueous solutions, we investigate the influence of the SBA-15 support on the Fe–Ni catalytic activity in the AB hydrolysis reaction. The SBA-15 support helps disperse the Fe–Ni alloy particles on its surface, which consequently improves the catalytic activity of the Fe–Ni. However, the presence of SBA-15 particles in the aqueous solution also retards the migration of the AB molecules in solution toward the Fe–Ni catalysts, increasing the induction time of the AB hydrolysis reaction. Therefore, there is an optimal Fe–Ni content in Fe–Ni/SBA for the catalysis of the AB hydrolysis reaction.

► SBA-15 support helps disperse Fe–Ni particles.
► SBA-15 improves catalytic activity of Fe–Ni.
► SBA-15 retards ammonium borane diffusion in aqueous solutions.
► The optimum Fe–Ni content in Fe–Ni/SBA catalyst is 50 wt.%.