Effect of La2O3 on Microstructure and Catalytic Performance of CuO/CeO2 Catalyst in Water-Gas Shift Reaction

Abstract

The water-gas shift reaction was used to evaluate a series of La 2 O 3 modified CuO/CeO 2 catalysts that were prepared by a parallel co-precipitation method. The catalytic activity and thermal stability improved significantly upon the introduction of La 2 O 3 , and CuO/CeO 2 -La 2 O 3 (2 wt%) gave the highest activity and had the best thermal stability. The microstructure of the as-prepared CuO/CeO 2 -La 2 O 3 catalysts and/or the CeO 2 -La 2 O 3 supports was characterized by X-ray diffraction, N 2 physisorption, Raman spectroscopy, and temperature-programmed reduction. The results indicate that larger specific surface areas and smaller crystal sizes of CuO and CeO 2 result in improved catalytic performance for the as-prepared catalysts. Moreover, the incorporation of La 3+ into the ceria lattice promotes the generation of oxygen vacancies leading to a higher number of moderate copper oxides that interact with surface oxygen vacancies on the surface of the ceria. This enhances the activity and thermal stability of the CuO/CeO 2 catalyst. 以 La 2 O 3 为助剂, 采用共沉淀法制备了具有良好催化活性和热稳定性的 CuO/CeO 2 -La 2 O 3 水煤气变换反应催化剂, 其中, 当 La 2 O 3 含量为 2 wt% 时, 催化剂的催化性能最为优异. 同时运用 X 射线衍射、N 2 吸附-脱附、Raman 光谱、程序升温还原等手段, 研究了不同含量的 La 2 O 3 对 CuO/CeO 2 催化剂微观结构及催化性能的影响. 结果表明, La 2 O 3 助剂进入了载体 CeO 2 的晶格并对 CuO/CeO 2 催化剂的微观结构和催化性能产生了直接影响, 适量 La 2 O 3 的添加可以抑制 CuO 和 CeO 2 晶格的长大、增强 CuO 与 CeO 2 间的相互作用、提高催化剂的比表面积、促进 CeO 2 载体中生成更多的氧空位, CuO/CeO 2 催化剂的催化活性和热稳定性也明显改善. The water-gas shift reaction was used to evaluate a series of CuO/CeO 2 -La 2 O 3 catalysts. The catalytic performance and microstructure of the CuO/CeO 2 catalysts were affected by the introduction of La. The CuO/CeO 2 -La 2 O 3 (2 wt%) catalyst gave the best catalytic performance because it showed the most significant improvement in microstructure.