Effect of the pH value of precursor solution on the catalytic performance of V₂O₅-WO₃/TiO₂ in the low temperature NH₃-SCR of NO_x

V₂O₅-WO₃/TiO₂ catalyst for the selective catalytic reduction of NO_x with NH₃ (NH₃-SCR) was prepared through wet impregnation and characterized by XPS, Raman spectra, H₂-TPR, NH₃-TPD, NH₃-DRIFT, XRD and physical adsorption. The effect of the pH value of vanadium precursor solution on the catalytic performance of V₂O₅-WO₃/TiO₂ in the low temperature NH₃-SCR of NO_x was investigated to optimize the preparation conditions. The results indicated that with the enhancement of precursor solution acidity, more polymeric vanadium species are formed on the catalyst surface; meanwhile, the ratio of V⁴⁺⁽³⁺⁾/V⁵⁺, surface acidity, and quantity of active sites are increased, whereas the de-NO_x performance of the V₂O₅-WO₃/TiO₂ catalyst is largely improved. As a result, a V₂O₅-WO₃/TiO₂ catalyst with high performance in de-NO_x through NH₃-SCR can be obtained by enhancing the precursor solution acidity in the preparation process.