Facile one-pot synthesis of Ni-based catalysts by cation-anion double hydrolysis method as highly active Ru-free catalysts for green H2 production via NH3 decomposition

Abstract

A series of Ni/Al1CeaOx composites prepared by various synthetic methods, including one-pot anion-cation double hydrolysis (CADH), co-precipitation (CP), CADH followed by wet impregnation (CADH-WI), and CP followed by wet impregnation (CP-WI) were employed as catalysts for ammonia (NH3) decomposition to generate hydrogen. The results revealed that the catalyst prepared by the one-pot CADH method exhibited outstanding catalytic performance (complete NH3 decomposition at around 550 °C) mainly because of significant enhancement in Ni dispersion, Ni reducibility, the quantity of surface oxygen vacancy, and NH3 adsorption affinity. The superior catalytic performance of Ce-containing catalysts over Ni/Al2O3 catalyst was ascribed to the synergistic effects of NiO reducibility, surface oxygen vacancies, basicity, and Ni-support interaction. The selected catalysts demonstrated excellent stability during 100 h continuous operation, without any obvious decrease in NH3 conversion. Overall, the proposed one-pot CADH method offers great advantages in preparing highly active and stable Ni-based catalysts for NH3 decomposition.