Promoting mechanism of CuO on catalytic performance of CeFe catalyst for simultaneous removal of NOx and CO

Abstract

Nitrogen oxides (NOx) and carbon monoxide (CO) coexisted in numerous industrial waste gases. And selective catalytic reduction of NOx with ammonia (NH3-SCR) and CO catalytic oxidation were considered as the effective technologies for simultaneous elimination of NOx and CO, respectively. However, an efficient bifunctional catalyst was crucial for achieving simultaneous removal of NOx and CO. Herein, we developed a series of Cu-modified CeFe catalysts for simultaneous removal of NOx and CO. The results demonstrated that 5Cu-CeFe catalyst presented the best catalytic performance, achieving approximately 81% NOx removal efficiency and nearly 99% CO conversion rate at 200 °C under a gas houely space velocity of 90,000 h−1. The XPS analysis demonstrated that copper oxides played a critical role in promoting the formation of Ce3+ and Oβ, thereby facilitating the NH3-SCR catalytic performance and CO catalytic oxidation. Moreover, the copper oxide modification of CeFe catalyst attained a trade-off between the surface acidity and redox ability, resulting in improving adsorption and activition capacity of the reactant gases. In situ DRIFTS experiments revealed that the NH3-SCR process primarily obeyed the Eley-Rideal (E-R) pathway over both CeFe and 5Cu-CeFe catalysts, while Langmuir-Hinshelwood (L-H) pathway hardly participated in NH3-SCR process. The presence of Cu+–CO species and surface lattice oxygen was crucial for CO oxidation, and both Mars-van Krevelen (M−K) and L-H pathways might be involved in the CO catalytic oxidation process over 5Cu-CeFe catalyst.