Preparation of Rh/Al2O3/Cr2O3 Monolithic Catalysts for Dichloromethane Combustion

A series of Rh catalysts supported on Al2O3 powder was prepared by impregnation method. Then a series of Rh/Al2O3-Cr2O3 monolithic catalysts was prepared by coating method, different proportions of Rh/Al2O3, Cr2O3 and aluminum gel were mixed into a homogeneous slurry, and then was coated onto the cordierite honeycomb ceramic. These catalysts with different Rh contents were tested for catalytic combustion of dichloromethane. It was found that the 0. 4 Rh/Al2O3-Cr2O3(Rh contents: 0. 4 g/L) had the highest activity and no chlorine. containing by. products were formed. The catalysts were characterized by various techniques such as XRD, H-2-TPR, NH3-TPD and BET. The results showed that the addition of Rh can improve the surface acidity and redox performance of the catalyst, and further improve the activity of the catalyst. It was believed that the activity of the catalyst was closely related to its reducibility and surface acidity. Moreover, the addition Cr2O3 is beneficial to the further oxidation of CH3Cl intermediate and thus improve the selectivity.