TiO2-modified CeVO4 catalyst for the selective catalytic reduction of NOx with NH3

Abstract

A series of TiO₂-modified CeVO₄ catalysts were prepared by the homogeneous precipitation method, among which the CeVTi₅ catalyst showed the best low-temperature NH₃-selective catalytic reduction (NH₃-SCR) activity at high GHSV. The CeVTi₅ catalyst also exhibited good H₂O and SO₂ durability. These catalysts were characterized by XRD, BET, Raman spectroscopy, H₂-TPR, XPS, and NH₃-TPD. The introduction of TiO₂ into CeVO₄ decreased the crystallite size, increased the surface area and the number of acid sites, and promoted the dispersion of active Ce and V species, leading to enhancement of the redox ability and interactions among Ce, V, and Ti, all of which favor the NH₃-SCR reaction. According to in situ DRIFTS results, modification with TiO₂ increased the number of Lewis acid sites and promoted the adsorption of NO_x. The NH₃-SCR reaction over the CeVTi₅ catalyst followed both the Langmuir–Hinshelwood and Eley–Rideal mechanisms, while only the Eley–Rideal mechanism was observed on the CeVO₄ catalyst.