Studies On The Structure And SCR Properties Of Supported V₂O₅/TiO₂ Catalysts With Preferentially Exposed Different Facets Of Anatase Supports

The structure and catalytic properties of supported V2O5/TiO2 catalysts with preferentially exposed different facets of anatase supports have been studied in this work by using BET surface area measurements,scanning electron microscope and transmission electron microscope(SEM/TEM),X-ray powder diffraction(XRD),NH3 temperature-programmed reaction and hydrogen temperature-programmed reduction(H2-TPR)combined with micro-reactor tests of selective catalytic reduction(SCR)of NO by NH3.The anatase TiO2 nano-sheets(TiO2-S)with preferentially exposed{001} facets and the anatase TiO2 nano-particles(TiO2-P)with preferentially exposed{101} facets have been prepared by HF-hydrothermal method and conventional sol-gel method,respectively.It has been found that the anatase supports with preferentially exposed different facets of anatase supports exert great influences on the SCR properties of supported V2O5/TiO2 catalysts,and the V2O5/TiO2-S catalysts with preferentially exposed anatase {001} facets exhibit higher SRC acticity than the V2O5/TiO2-P catalysts with preferentially exposed anatase {101} facets.The dispersion capacity of V2O5 on TiO2-S and TiO2-P supports were determined to be 1.63 mmol V/100 m2 TiO2-S and 1.04 mmol V/100 m2 TiO2-P.The higher VOx dispersion,lower polymerization degree and higher reducibility of VOx species dispersed on the anatase {001} facets are the main reasons for the unique low-temperature SCR properties of V2O5/TiO2-S catalysts.Adding WO3 components into the V2O5/TiO2 catalysts can increase their low-temperature SCR activities of V2O5/TiO2 catalysts and widen the temperature window of SCR reaction.It has been shown that V2O5-WO3/TiO2-S catalysts with preferentially exposed anatase{001} facets have higher SCR activity and wider temperature window of SCR reaction than the V2O5-WO3/TiO2-P catalysts with preferentially exposed anatase {101} facets,and the optimum loading of WO3 on theV2O5-WO3/TiO2-S catalyst was determined to be ca 1.0 mmol W/100m2 TiO2.