Multicomponent Ni–Y₂O₃–Al₂O₃ Nanospheres as Highly Efficient Catalysts for the Ammonia Decomposition Reaction

Abstract

Ammonia is a promising hydrogen storage medium, and the catalytic decomposition of ammonia offers a route to clean hydrogen generation. Constructing efficient multicomponent catalysts with an appropriate choice of components is a feasible strategy to enhance the catalytic performance in ammonia decomposition. In this work, a series of multicomponent Ni–Y2O3–Al2O3 catalysts with a unique internal hollow spherical structure were synthesized by a facile aerosol-assisted self-assembly approach. Compared with the Ni–Y2O3 and Ni–Al2O3 catalysts, the Ni–Y2O3–Al2O3 catalysts exhibited a significant advantage in the catalytic performance of ammonia decomposition, and their activity remained stable during tests up to 100 h under very harsh reaction conditions (550 °C and space velocity of 60,000 mL·gcat –1·h–1), outperforming almost all Ni-based catalysts reported so far. Systematic characterizations demonstrated that Y2O3 effectively dispersed Ni nanoparticles, alleviated the poisoning effect of H2 on the catalysts, and provided sufficient basic sites to improve the catalytic activity. In addition, the introduction of Al2O3 further inhibited the aggregation of Ni and Y2O3 nanoparticles and maintained their high dispersion in the reaction. This work elucidates the contribution of different compositions in multicomponent catalysts and provides a strategy for the construction of efficient Ni-based ammonia decomposition catalysts.