HCHO Catalytic Oxidation Performance over Cerium Containing MCM-41 Type Mesoporous Materials Supported Ag Catalysts

Abstract

Understanding the effects of cerium in the formaldehyde (HCHO) catalytic oxidation performance over Ag/MCM-41 catalysts, cerium modified MCM-41 mesoporous materials (Ce-MCM-41) with different ratios were synthesized by one-step hydrothermal method. The activity test results showed that Ag/Ce-MCM-41 with the ratio of Si:Ce = 1:1 catalysts could reach complete HCHO oxidation above 130 °C. These Ag/Ce-MCM-41 catalysts with different Si:Ce ratios were characterized by IR, SXRD, XRD, TEM, UV–Vis, Raman, XPS and H2-TPR. The results show that the interactions between Ag and Ce, between Ce and SiO2 in our Ag/Ce-MCM-41 are enhanced due to adding Ce to MCM-41. The presence of Ce-SiO2 interaction dramatically enhances the reducibility of surface-capping oxygen of CeO2, promotes the bulk oxygen migration to the surface and creates oxygen vacancies in the bulk region of CeO2 and the presence of more oxygen vacancies can facilitate the anchoring and dispersing of Ag particles, which lastly improves the interaction between Ag and Ce. In addition, the amount of formed oxygen vacancy is the highest when the Si:Ce = 1:1. The activation of surface oxygen is closely related to oxygen vacancy, O2 may be transformed into the highly active O2−. The high active O2− in surface adsorbed oxygen promotes the activation of oxygen molecules and enhanced the catalytic oxidation of HCHO.