Ce0.5Zr0.5O2 solid solutions supported Co-Ni catalyst for ammonia oxidative decomposition to hydrogen

Abstract

A series of CexZr1-xO2 catalysts with different Ce content (x = 1, 0.80, 0.75, 0.50, 0.33) were synthesized by co-precipitation method. The partial doping of Zr in CeO2 framework was observed to enhance the surface area and increase oxygen vacancy of the catalyst, which resulted in promoting of both NH3 oxidation and dehydrogenation in the NH3 oxidative decomposition process. The structural property of the catalysts were characterized by various methods, including XRD, BET, TEM, NH3-TPD, H2-TPR and XPS. It appears that the 5 wt% Co − 5 wt% Ni/Ce0.5Zr0.5O2 (CNCZ-55) catalyst demonstrates excellent activity in the given experimental conditions. The results indicate that when NH3 / O2 = 1:0.25, the conversion rates of both ammonia and oxygen reach 97% and 100%, respectively. Additionally, the hydrogen production achieved a notable efficiency of 63%. Moreover, the stability and repeatability of the CNCZ-55 catalyst have been obtained over 5 cycles and a total experimental duration of 100 h. This suggests that the catalyst exhibits good durability and can consistently perform well in the given reaction conditions. This design concept of improving the performance by optimizing the catalyst carrier may be broadly applicable to catalysts for a wide range of NH3 decomposition and H2 production reaction.