The poisoning and regeneration effect of alkali metals deposed over commercial V_2O_5-WO_3/TiO_2 cat

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In this study,commercial V2O5-WO3/TiO2catalysts were deactivated by loading with alkali metals(K and Na).These catalysts were then regenerated by washing with either deionized water or 0.5 mol/L H2SO4(through the ultrasonic-assisted method).The samples used in this research were characterized by NH3-temperature programmed desorption(TPD),and X-ray photoelectron spectroscopy(XPS).Results showed that Na2O and K2O doping can poison the V2O5-WO3/TiO2catalyst and that the poisoning effect of Na2O was stronger than that of K2O.However,the Na2O-loaded sample was easier to regenerate than the K2O-loaded sample.The surfaces of catalysts can be sulfated by washing with dilute sulfuric acid because strong acid sites adhere to the catalyst surface.SO42-could also promote catalyst activity.As indicated by the NH3-TPD findings,the deposition of Na2O and K2O could also reduce the amount of desorbed ammonia and destabilize the acid sites,especially strong chemisorption sites.XPS results revealed that catalysts were deactivated by the decrease in the concentration of chemisorbed oxygen[the Oa/(Oα+Oβ)ratio].In the Na2O-doped catalyst,much chemisorbed oxygen was lost(from 28.8%to10.6%).However,the decrease in the Oa/(Oα+Oβ)ratio was less significant in the K2O-doped catalyst(from28.8%to 23.5%).Nonetheless,the binding energies of O1s broadened with respect to both high and low energy.In particular,the binding energy of chemisorbed oxygen increased from 531.5 to 531.8 eV. In this study, commercial V2O5-WO3 / TiO2catalysts were deactivated by loading with alkali metals (K and Na) .These catalysts were then regenerated by washing with either deionized water or 0.5 mol / L H2SO4 through the ultrasonic-assisted method. Samples used in this research were characterized by NH3-temperature programmed desorption (TPD), and X-ray photoelectron spectroscopy (XPS) .Results showed that Na2O and K2O doping can poison the V2O5-WO3 / TiO2catalyst and that the poisoning effect of Na2O was stronger than that of K2O.However, the Na2O-loaded sample was easier to regenerate than the K2O-loaded sample. The surfaces of catalysts can be sulfated by washing with dilute sulfuric acid because of strong acid sites adhere to the catalyst surface. SO42-could also promote catalyst activity. As indicated by the NH3-TPD findings, the deposition of Na2O and K2O could also reduce the amount of desorbed ammonia and destabilize the acid sites, especially strong chemisorption sites. XPS results revealed that The enzymes were deactivated by the decrease in the concentration of chemisorbed oxygen [the Oa / (Oα + Oβ) ratio]. The Na2O-doped catalyst, much chemisorbed oxygen was lost (from 28.8% to 10.6%). However, the decrease in the Oa / (Oα + Oβ) ratio was less significant in the K2O-doped catalyst (from 28.8% to 23.5%). Nonetheless, the binding energies of O1s broadened with respect to both high and low energy. binding energy of chemisorbed oxygen increased from 531.5 to 531.8 eV.
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