Chemisorption and kinetic mechanisms of elemental mercury on immobilized V2O5/TiO2 at low temperatures

To investigate the effect of low temperature and catalyst filling pattern on the adsorption of Hg degrees by DeNOx equipment, the chemisorption and kinetic mechanisms of Hg degrees adsorption on 5-30%V2O5/TiO2 immobilized on glass beads at 100-160 degrees C were investigated. The effects of the reaction temperature, influent Hg degrees concentration, and V2O5 doping amount on the adsorption efficiency and capacity for Hg degrees were explored. The active sites for Hg degrees adsorption were further identified. Additionally, the adsorption kinetics were modelled using the linear driving force approximation, Fick's diffusion model, and pseudo-second-order kinetic model. Finally, the influence of immobilization on the adsorption of Hg degrees was also investigated. Experimental results showed that the bridged oxygen atom of V-O-V played a key role in the adsorption of Hg degrees. The Hg degrees adsorption efficiencies decreased from > 90% to 40% as the reaction temperature increased from 120 degrees C to 160 degrees C for 20%V2O5/TiO2, while the adsorptive capacities for Hg degrees were highly influenced by the influent Hg degrees concentration and V2O5 doping amount. 20%V2O5/TiO2 had the highest adsorptive capacity of 2547 mu g Hg degrees/g V2O5/TiO2 at 160 degrees C. The kinetic results showed that the linear driving force approximation model fit the Hg degrees adsorption better than the other models. The diffusion resistance increased significantly for the immobilized catalysts because the external mass transfer coefficient decreased by more than 1200-fold.