Co-Ni supported yttrium oxide material as a catalyst for ammonia decomposition to COx-free hydrogen

Abstract

The preparation of CO2-free hydrogen by decomposing ammonia using non-precious metal catalysts has received widespread attention. Co-based catalysts have good catalytic activity and low synthesis costs. Therefore, we prepared a series of Y2O3-loaded Co and Co–Ni bimetallic catalysts by the co-precipitation method. The structure-activity relationship of the catalysts during NH3 decomposition was investigated by X-ray diffraction, N2 adsorption-desorption, transmission electron microscopy, and Temperature-programmed reduction by hydrogen. The ammonia decomposition performance of the bimetallic Co–Ni was examined to elucidate the effect of the relative amount of the active metal of the catalyst on the catalytic activity and compared it with the monometallic Co/Y2O3. Among the tested catalysts, 20Co–10Ni/Y2O3 showed the best catalytic performance as well as good stability. The ammonia decomposition rate of the 20Co–10Ni/Y2O3 catalyst was 85.02% at 550 °C and GHSV of 9000 mL h−1·gcat−1, which was 28.5% higher than that of the 20Co/Y2O3 catalyst. The high activity of 20Co–10Ni/Y2O3 catalyst was attributed to the uniform loading of Co and Ni, high specific surface area, and a large number of mesopores. At the same time, Co and Ni exhibited synergistic effects to produce suitable adsorption energy of nitrogen atoms, which further enhanced the catalytic activity of the catalyst.