Promotion Effect of Chromium on the Activity and SO₂ Resistance of CeO₂–TiO₂ Catalysts for the NH₃-SCR Reaction

The Cr-doped CeO 2 –TiO 2 catalysts (CrCeTi) were produced via a coprecipitation method and used for selective catalytic reduction (SCR). The CrCeTi catalyst has good catalytic performance and sulfur resistance. The results of X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), NH 3 -TPD, NO-TPD, X-ray photoelectron spectroscopy (XPS), and H 2 temperature-programmed reduction (H 2 -TPR) suggested that the CrCeTi catalyst with high specific surface area (SSA), strong surface acidity, enhanced redox properties, and effective electron transfer (3Ce 4+ + Cr 3+ ↔ 3Ce 3+ + Cr 6+ ) were the important promotion factors for excellent SCR properties. The in situ diffuse reflectance infrared spectroscopy (DRIFTS) indicated that the incorporation of Cr could improve the adsorption capacity of nitrate and the activation capacity of NH 3, which were conducive to enhancing the catalytic activity. The thermogravimetric analysis-mass spectrometry (TG-MS) confirmed that the doping of Cr reduced SO 2 surface adsorption and promoted the decomposition of NH 4 HSO 4 (ABS). Therefore, the CrCeTi catalyst showed excellent resistance to SO 2 poisoning.