Investigation of the promotion effect of Mo doped CuO catalysts for the low-temperature performance of NH3-SCR reaction

A novel Mo-doped CuO catalyst is developed and used for low-temperature NH3-SCR reaction. Compared with the undoped CuO sample, the Mo doped CuO catalyst shows an increased SCR performance with above 80% NOx conversion at 175 °C. The XRD and Raman results have confirmed the incorporation of Mo metal ions into CuO lattice to form Mo-O-Cu species which may be related to the enhanced SCR activity. The XPS and UV–vis results reveal the creation of electron interaction between Cu and Mo in this Mo-O-Cu system which provides an increased amount of Lewis and Brønsted acid sites, thereby promoting the adsorption capacity of NH3 and NOx as verified by NH3-TPD and NOx-TPD characterization. Besides, it also promotes the formation of oxygen vacancies, leading to the increasing of chemisorbed oxygen species, which improves the NO oxidation to NO2 activity. Furthermore, in situ DRIFTS technology was also used to study the reaction mechanism of this Mo doped CuO catalyst. The formed NO2 could react with NHx (x = 3, 2) species to enhance the low-temperature NH3-SCR activity via the “fast-SCR” reaction pathway. The nitrate and nitrite ad-species may react with NH3 and NH4+ ad-species through the L-H pathway. [Display omitted]