Non-noble catalysts formulations using CuO-CeO₂/Nb₂O₅ for low-temperature catalytic oxidation of carbon monoxide

Eliminating Carbon Monoxide (CO) by oxidation using efficient and affordable catalysts holds significant potential for addressing various industrial and environmental challenges. In this study, we investigate the low-temperature oxidation of CO for a broad range of catalysts, while we investigate the effect of moisture and the presence of oxygen for the best -performing catalyst. Ceria oxide (CeO₂) and copper oxide (CuO) catalysts supported on niobium oxide (Nb₂O₅) were synthesized at various loadings, characterized, and tested for the oxidation of carbon monoxide. Several different techniques were used including, X-ray diffraction (XRD), Fourier Transform Infrared (FT-IR), Transmission electron microscopy (TEM), N₂ Adsorption-desorption (BET), and Raman spectroscopy, to investigate the physiochemical properties of the prepared catalysts and their effect on the desired catalytic activity. XRD findings indicated that there were synergistic interactions between copper oxide (CuO) and CeO₂ BET results revealed that synthesized catalysts have high surface area and uniform pore size distribution over supports. It was found that a 10% CuO-CeO₂ supported on Nb₂O₅ shows a significantly improved performance among all the catalysts with full conversion observed at temperatures as low as 150℃. This catalyst endures high stability over a long reaction time (stability tests are performed up to 12 hours). Kinetics parameters were also determined where the fitted activation energy (23.1 kJ mol^-1) follows the CO activity trends. The second best-performing catalyst CuO-CeO₂ demonstrated remarkable versatility in adapting to a wide range of space velocities, ranging from 14,400 to 25,200 cm³ g^-1 h^-1. The effect of excess oxygen (λ) in the feed was also determined and discussed in detail. DFT computations provided the energy profile for the surface oxidation of CO. Results from this work pave the way to formulate low-temperature catalytic operations for the oxidation of CO at practical conditions, i.e., to treat the effluents from internal combustion engines.