Recent Progress in CO Oxidation over Non-precious-metal Catalysts

A robust catalyst for carbon monoxide (CO) oxidation at lower temperature is critical to protecting the environment, improving human quality of life, and saving fuels. Compared with scarce and expensive noble-metal species (such as Au, Pt, Pd, etc.), recent years have seen tremendous efforts to develop non-precious-metal catalysts (NPCs, such as Cu, Mn, Ce, etc.) for wide application in industrial or civil CO oxidations, resulting in a proliferation of newly emerged NPCs and deep understandings of the active sites and catalytic mechanisms. Here, the NPCs with a focus on the synergy effects of multiple elements on the activity of CO oxidation are simply summarized. First, the fundamental mechanisms of CO catalytic oxidation of CO over NPCs are briefly introduced. Next, with nearly 20 elements as classification indexes, the catalytic characteristics, merits, and typical cases of NPCs in the CO catalytic oxidation process are classified and summarized. Meanwhile, in the typical cases, some strategies that are independent of the elements and can significantly improve the catalytic efficiency are also listed, such as nanosized structures, enlarged-surface areas, polycation enhancement, etc. Finaly, the deactivation of NPCs including H2O and SO2 poisoning, carbon deposition (coking), and thermal degradation (sintering), as well as the ways to control deactivation and regeneration, are summarized. This Review exhibits a scientific basis for the potential design of NPCs for CO oxidation.