Synergistic catalysis of NO and chlorobenzene over Mn3O4-CeO2 catalysts: Acid sites, catalytic pathway and mechanism

Abstract

Catalyst active sites and surface acidity are crucial for the synergistic catalysis of NOx and dioxins, determining the selectivity towards N2 and CO2. This study synthesized Mn3O4-CeO2 catalysts to investigate the influence of these sites on the catalytic performance for NO and chlorobenzene. Mn0.086Ce, made by the redox method, showed the highest Mn-Ce interface, achieving nearly complete conversion of chlorobenzene and NO at 180℃, with CO2 and N2 selectivity reaching about 80 % and 100 %, respectively. EPR, NH3-TPD and Py-IR analyses revealed that the Mn-Ce interface induces the formation of Lewis acid sites and oxygen vacancies, facilitating the adsorption and conversion of chlorobenzene, NH3, and NO. Mn adjacent to Lewis acid sites is the main active site, while Ce acts as an electron transfer agent. Based on the results of in-situ DRIFTS and TOF-SIMS, the possible degradation pathway for chlorobenzene was proposed and as follows: phenol, benzoquinone, maleic anhydride, propionic acid, CO2, and H2O. The NH3-SCR reaction follows the Eley-Rideal mechanism at 150–300℃.