Metal-support interaction induced ZnO overlayer in Cu@ZnO/Al2O3 catalysts toward low-temperature water-gas shift reaction

The water-gas shift reaction (WGSR) plays a pivotal role in many important industrial processes as well as in the elimination of residual CO in feed gas for fuel cells. The development of a high-efficiency low-temperature WGSR (LT-WGSR) catalyst has attracted considerable attention. Herein, we report a ZnO-modified Cu-based nanocatalyst (denoted as Cu@ZnO/Al2O3) obtained via an in situ topological transformation from a Cu2Zn1Al-layered double hydroxide (Cu2Zn1Al-LDH) precursor at different reduction temperatures. The optimal Cu@ZnO/Al2O3-300R catalyst with appropriately abundant Cu@ZnO interface structure shows superior catalytic performance toward the LT-WGSR with a reaction rate of up to 19.47 mu mol(CO) g(cat)(-1) s(-1) at 175 degrees C, which is similar to 5 times larger than the commercial Cu/ZnO/Al2O3 catalyst. High-resolution transmission electron microscopy (HRTEM) proves that the reduction treatment results in the coverage of Cu nanoparticles by ZnO overlayers induced by a strong metal-support interaction (SMSI). Furthermore, the generation of the coating layers of ZnO structure is conducive to stabilize Cu nanoparticles, accounting for long-term stability under the reaction conditions and excellent start/stop cycle of the Cu@ZnO/Al2O3-300R catalyst. This study provides a high-efficiency and low-cost Cu-based catalyst for the LT-WGSR and gives a concrete example to help understand the role of Cu@ZnO interface structure in dominating the catalytic activity and stability toward WGSR.

Automated summary

This study reports a new Cu-based nanocatalyst (Cu@ZnO/Al2O3) with superior catalytic performance and stability in low-temperature water-gas shift reaction (LT-WGSR). The catalyst, with abundant Cu@ZnO interface structure, shows a reaction rate 5 times higher than the commercial catalyst at 175℃.