A series of Co3O4-CeO2 binary oxides with various Co/(Ce+Co) molar ratios were synthesized using a citric acid method, and their catalytic properties toward the total oxidation of propane were examined. The activities of the catalysts decrease in the order CoCeOx-70 > CoCeOx-90 > Co3O4 > CoCe-Ox-50 > CoCeOx-20 > CeO2. CoCeOx-70 (Co/(Ce+Co) = 70% molar ratio) exhibits the highest catalytic activity toward the total oxidation of propane, of which the T90 is 310 °C (GHSV = 120000 mL h 1 g 1), which is 25 °C lower than that of pure Co3O4. The enhancement of the catalytic performance of CoCeOx-70 is attributed to the strong interaction between CeO2 and Co3O4, the improvement of the low-temperature reducibility, and the increase in the number of active oxygen species. In-situ DRIFTS and reaction kinetics measurement reveal that Ce addition does not change the reaction mechanism, but promotes the adsorption and activation of propane on the catalyst surface. The addition of water vapor and CO2 in reactant gas has a negative effect on the propane conversion, and the catalyst is more sensitive to water vapor than to CO2. In addition, CoCeOx-70 exhibits excellent stability and reusability in water vapor and CO2 atmosphere.
Effective utilization of coal bed methane is very significant for energy utilization and environment protection. Catalytic combustion of methane is a promising way to eliminate trace amounts of oxygen in the coal bed methane and the key to this technology is the development of high-efficiency catalysts. Herein, we report a series of CeLaO (x = 0-0.8) monolithic catalysts for the catalytic combustion of methane, which are prepared by citric acid method. The structural characterization shows that the substitution of La enhance the oxygen vacancy concentration and reducibility of the supports and promote the migration of the surface oxygen, as a result improve the catalytic activity of CeO. M-CeLaO (monolithic catalyst, CeLaO coated on cordierite honeycomb) exhibits outstanding activity for methane combustion, and the temperature for 10 and 90% methane conversion are 495 and 580 °C, respectively. Additionally, CeLaO monolithic catalyst presents excellent stability at high temperature. These CeLaO monolithic materials with a small amount of La incorporation therefore show promises as highly efficient solid solution catalysts for lean-oxygen methane combustion. Graphical abstract ᅟ.
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