Improving the Performance of Gd Addition on Catalytic Activity and SO2 Resistance over MnOx/ZSM-5 Catalysts for Low-Temperature NH3-SCR

SO2 poisoning is a great challenge for the practical application of Mn-based catalysts in low-temperature selective catalytic reduction (SCR) reactions NOx with NH3. A series Gadolinium (Gd)-modified MnOx/ZSM-5 were synthesized via citric acid–ethanol dispersion method and evaluated by NH3-SCR. Among them, GdMn/Z-0.3 catalyst molar ratio Gd/Mn 0.3 presented highest activity, which 100% NO conversion could be obtained temperature range 120–240 °C. Furthermore, exhibited good resistance compared Mn/Z presence 100 ppm SO2. The results Brunauer–Emmett–Teller (BET), X-ray photoelectron spectroscopy (XPS), temperature-programmed H2 (H2-TPR) desorption NH3 (NH3-TPD) illustrated that such performance was mainly caused large surface area, abundant Mn4+ chemisorbed oxygen species, strong reducibility suitable acidity catalyst. situ diffuse reflectance infrared Fourier transform spectra (DRIFTS) revealed addition Gd greatly inhibited reaction between MnOx active sites to form bulk manganese sulfate, thus contributing high resistance. Moreover, DRIFTS experiments also shed light on mechanism SCR over GdMn/Z-0.3, both followed Langmuir–Hinshelwood (L–H) Eley–Rideal (E–R) mechanism.