Role of cation in catalytic decomposition of ammonia over Ni supported zeolite Y catalysts

Abstract

A series of nickel (Ni) catalysts were prepared using zeolites Y with different cation types (Na, Mg, Ca, Sr, Ba, Ce, and La) as supports and characterized by using XRD, BET, ICP-OES, XPS, and TEM, as well as NH3-TPD, CO2-TPD, and H2-TPR techniques. Their catalytic performances in decomposition of ammonia (NH3) to hydrogen (H2) were evaluated with a fixed-bed flow reactor system. The catalytic activities of the prepared catalysts for NH3 decomposition decreased in the order of Ni/SrY > Ni/BaY > Ni/LaY > Ni/CaY > Ni/NaY > Ni/MgY > Ni/CeY. The high activity of Ni/SrY catalyst may be attributed to its small Ni nanoparticle size, high basicity and strong interaction between highly dispersed Ni nanoparticles and SrY support. At 600 °C and GHSV of 9000 mLNH3·gcat−1·h−1, 98.0 % NH3 conversion with about 105.2 mmol min−1·gNi−1 H2 formation rate can be accomplished over Ni/SrY catalyst.