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 Cu0 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+/Cu0 ratio of 1.2 and exhibits ∼5 times higher reaction rate compared to Cu/ZnO/Al2O3 at 200 °C. In situ characterization results further demonstrate that the as-prepared Cu–Zn–Al catalysts follow an association mechanism.