科研之友
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摘要
V2O5-MoO3-TiO2 (V-Mo-Ti) is often used as a selective catalytic reduction catalyst for NOx from coal-fired flue gas. The performance of a V-Mo-Ti catalyst for the oxidation of elemental mercury (Hg-0) was investigated. It was found that Mo was resistant toward sulfur dioxide and can enhance the Hg-0 adsorption capacity. Ag was employed to enhance the Hg-0 oxidation reaction and can enlarge reaction temperature Doping with Ag can significantly enhance the oxidation of Hg-0, and adding only 0.5% Ag can keep Hg-0 oxidation efficiency to approximately 90% with 5 ppm HCl, with an increase of 20-40% compared to that of V-Mo-Ti catalyst. Besides, the reaction temperature window of catalyst was enlarged from 150 to 400 degrees C. TEM and XPS characterization data indicated that Ag nanoparticles were loaded on the Mo/V-Ti carrier, maintaining Ag-Mo/V-Ti at a higher oxidation state. Furthermore, the TPR and Deacon reaction tests suggested that the Ag dopant might enhance the redox behavior, which facilitates the Deacon or semi-Deacon reactions for HCl activation. In addition, Hg-0 desorption and breakthrough experiments and mercury valence state change experiments were carried out to investigate the Hg catalytic oxidation mechanisms at various temperature ranges.
