Studies on reaction mechanism of SO2 reduction catalyzed by CeO2-La2O3/γ-Al2O3

Supported catalysts CeO2/gamma-Al2O3, La2O3/gamma-Al2O3 and CeO2-La2O3/gamma-Al2O3 were prepared by impregnation. The studies were engaged in the catalytic reduction of SO, by CO over the catalysts under the following conditions: feed gas 25 % SO2-75% CO, with N-2 as a carrier gas, flow rate 1 L/min and catalyst mass 15 g. The activation process and catalytic activity of the catalysts, as well as the effect of the concentration ratio of the reactants on the catalytic reaction were investigated. The XRD and XPS were used to characterize the catalysts before and after the reaction. The result demonstrated that the activation temperature of CeO2-La2O3/gamma-Al2O3 is 50 similar to 100 degreesC lower than that of La2O3/gamma-Al2O3 or CeO2/gamma-Al2O3, and CeO2-La2O3/gamma-Al2O3 has higher activity than La2O3/gamma-Al2O3 or CeO2/gamma-Al2O3 for catalytic reduction of SO2 by CO. This result revealed the synergism between redox reaction of CeO2 and COS intermediate reaction of La2O3. The experimental results showed that the generation of elemental sulfur from the redox reaction of CeO2 was an important source of COS intermediate reaction through the whole reaction, based on which a redox-COS overlapped reaction mechanism was proposed for the reduction of SO2 by CO over CeO2-La2O3/gamma-Al2O3.