Hydrogen production by the catalytic decomposition of ammonia over a Ru/SiCeOx catalyst: The synergistic effect of Si addition

Abstract

Controlling active metal–support interaction is critical in the catalytic decomposition of ammonia (NH3). In this study, we investigated the generation of oxygen vacancies in the SiCeOx support by Si addition and the increase in catalytic performance for the decomposition of NH3 by their interaction with Ru. The Si content in the Ru/SiCeOx catalysts was controlled by glassware elution during the precipitation of Ce(NO3)3 at a high pH level (10.5) by applying different aging temperatures and times. The formation of oxygen vacancies by the insertion of Si4+ into the CeO2 lattice was characterized by O2-pulse experiments as well as Raman and X-ray photoelectron spectroscopy analyses. The effect of oxygen vacancies on the adsorption strengths of hydrogen and nitrogen on Ru was characterized by H2-temperature-programmed reduction and NH3-temperature-programmed desorption. The correlation between NH3 conversion, oxygen vacancy content, and nitrogen desorption temperature was experimentally proven.