Facile Synthesis of Efficient and Robust Cu-Zn-Al Catalysts by the Sol-Gel Method for the Water-Gas Shift Reaction

The water-gas shift reaction is widely employed in hydrogen production. Herein, we report a facile sol-gel method for preparing Cu-Zn-Al catalysts with significantly suppressed Cu and Zn contents compared with commercial Cu/ZnO/Al2O3. We discover that Zn species are not only to augment the proportion of Cu+ species to increase the concentration of adsorbed CO on catalysts, thereby promoting the formation of intermediate species; but also to decrease the size of Cu-0 nanoparticles, which accelerates the decomposition of reaction intermediates and the desorption of products. Both advantages significantly improve the performance and stability of the catalysts, especially for CuZnAl-10. It contains 12 wt % Cu and 1.2 wt % Zn with the optimal Cu+/Cu-0 ratio of 1.2 and exhibits similar to 5 times higher reaction rate compared to Cu/ZnO/Al2O3 at 200 degrees C. In situ characterization results further demonstrate that the as-prepared Cu-Zn-Al catalysts follow an association mechanism.