The Al promotional effect for Ce 0.4 Zr 0.6 O 2 mixed oxides in selective catalytic oxidation of ammonia to nitrogen

Simultaneous catalytic oxidation of toluene and CO over Cu-V/Al-Ce catalysts: Physicochemical properties-activity relationship and simultaneous oxidation mechanism

Cu-V/Al-Ce with varying ratios of Al2O3/CeO2 were prepared to study the simultaneous catalytic oxidation of toluene and CO. Experimental results show that Cu-V/20Al-80Ce exhibits optimal simultaneous oxidation activity and good durability. This superior performance is related to Cu-Ce, V-Ce, and Al-Ce interactions, which facilitate the exposure of active centers, the creation of oxygen vacanicies, and efficient electron transfer. The mutual influence between toluene and CO during the simultaneous oxidation is then demonstrated. Toluene hinders CO oxidation through the competitive adsorption and the consumption of reactive oxygen species. CO enhances toluene oxidation, which is comprehensively explained by affecting the competition between the desorption and oxidation of benzaldehyde. Despite the mutual influence between toluene and CO, the pathways of CO and toluene oxidation are mutually independent. Toluene oxidation proceeds sequentially from toluene to benzyl alcohol, benzaldehyde, benzoate, and finally to CO2. Before being completely oxidized to CO2, CO is initially converted to carboxylic acid, hydrogen carbonate, free carbonate ion, bidentate formate, and monodentate carbonate.

Quantum chemistry study on the oxidation of NO catalyzed by ZSM5 supported Mn/Co–Al/Ce

The detailed mechanism of NO oxidation catalyzed by ZSM5 supported Mn/Co–Al/Ce is investigated and revealed by Quantum Chemistry Calculation. A three-step catalytic mechanism for NO oxidation is proposed and studied. Theoretical results show that, the activate energies of reactions catalyzed by ZSM-5 supported Mn/Co (71.1[Formula: see text]kJ/mol/80.6[Formula: see text]kJ/mol) are much lower than that obtained from the direct NO oxidation. This indicates that the ZSM-5 supported Mn/Co has an obvious catalytic effect. When the active center Si is replaced by Al and Ce, the activation energies are further decreased to about 40[Formula: see text]kJ/mol. This indicates that the doping of Al and Ce can obviously improve the catalytic effect. The theoretical study illustrates that the catalysts for NO oxidation not only relate to the supported transition metal such as Co and Mn, but also highly relate to the activity centers such as Al and Ce.