Effect of acid sites modification on the catalytic combustion of 1,2-dichlo- roethane: Revealing the synergy between NbOx and CeO2

1,2-Dichloroethane are primarily sourced from the emissions of the chlor-alkali industry, resulting in severe pollution of soil, air, and water. In this work, Nb/CeO2 catalysts were prepared by impregnation method, and their performance for EDC oxidation was evaluated. The addition of Nb improved the activity, selectivity, and stability of CeO2. Nb was highly dispersed on CeO2 surface in the form of NbOx, and partially entered the lattice of CeO2. This caused lattice distortion and more surface defects, thereby increasing the number of oxygen vacancies. Nb-O-Ce bonds formed in between Nb and CeO2 weakened the Ce--O bonds and enhanced lattice oxygen mobility. The presence of NbOx increased the number of Lewis acid (Nb--O) and Bronsted acid (Nb-OH) sites, which facilitated the cleavage of C-Cl and C-C bonds. Increased acidity promoted the removal of Cl species in the form of HCl and effectively mitigated the chlorine poisoning of CeO2. In-situ DRIFTS results indicated that EDC oxidation on Nb/CeO2 catalysts followed a Mars-van Krevelen mechanism and progressed via the pathway of alcoholate-* formate/methoxy-* COx.