Alkali-induced deactivation mechanism of V2O5-WO3/TiO2 catalyst during selective catalytic reduction of NO by NH3 in aluminum hydrate calcining flue gas

摘要

NOx in the flue gas from aluminum hydrate calcining process is the main emission source among the aluminum manufacture industries. The water vapor, various aluminum compounds, and sodium compounds in alumina calcining flue gas affect the NH3-SCR reaction. In this study, we investigated the deactivation mechanism by alkali metals via doping of Al2O3, Al(OH)(3), Na2O, and NaOH over commercial V2O5-WO3/TiO2 catalysts. The results indicated that the doping of Al2O3, Al(OH)(3), NaOH, and Na2O reduced the NH3-SCR activities and it followed the order of NaOH > Na2O > Al2O3 similar to Al(OH)(3). The injection of water vapor could result in about 20 % NO conversation efficiency decreasing. According to the intoxication mechanism study, Al species tend to reduce Lewis acidic sites and Na compounds could decrease both Bronsted and Lewis acidic sites. Na has strong interaction with active V species, with decrease of V5+ species and the reducibility. Al has a weak binding tendency with both V and W, with decrease of NH3 absorption on V species and electron density around W. This study was favorable for further SCR catalyst modification and application in the manufacture industry.