Development of non-noble Ni metal-based (Yb1−xCox)2O3−δ catalysts for green H2 production via ammonia decomposition

Abstract

We herein report the preparation of non-noble metal supported Yb₂O₃–Co₃O₄ inorganic catalysts for application in H₂ production via ammonia (NH₃) decomposition. The NH₃ decomposition reaction for H₂ production was studied using αwt%Ni/(Yb_1−xCo_x)₂O_3−δ catalysts according to various Co dopant ratios and Ni loadings to evaluate the dependence of oxygen vacancies as active sites. The introduction of Co₃O₄ into Yb₂O₃ with a Ni metal support improved the oxygen vacancy density of the catalyst to enhance NH₃ decomposition activity for H₂ production. The electron-deficient nature of oxygen vacancies enabled the catalysts to act as electron acceptors, facilitating the associative N desorption from NH₃ to produce N₂ in the NH₃ cracking process. The structure–property relationship established in these studies suggests that the oxygen vacancies on the αwt%Ni/(Yb_1−xCo_x)₂O_3−δ catalysts serve as active sites for NH₃ decomposition. The 16wt%Ni/(Yb_0.92Co_0.08)₂O_3−δ catalyst showed the highest catalytic activity, which exhibited an NH₃ conversion of 100% at temperatures as low as 550 °C and the constant H₂ production rate of 6.23 kg per day.