Effect of SO2 on the Selective Catalytic Reduction of NOx over V2O5-CeO2/TiO2-ZrO2 Catalysts

Abstract

The effect of SO2 on the selective catalytic reduction of NOx by NH3 over V2O5-0.2CeO2/TiO2-ZrO2 catalysts was studied through catalytic activity tests and various characterization methods, like Brunner−Emmet−Teller (BET) surface measurement, X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray fluorescence (XRF), hydrogen temperature-programmed desorption (H2-TPR), X-ray photoelectron spectroscopy (XPS) and in situ diffused reflectance infrared Fourier transform spectroscopy (DRIFTS). The results showed that the catalyst exhibited superior SO2 resistance when the volume fraction of SO2 was below 0.02%. As the SO2 concentration further increased, the NOx conversion exhibited some degree of decline but could restore to the original level when stopping feeding SO2. The deactivation of the catalyst caused by water in the flue gas was reversible. However, when 10% H2O was introduced together with 0.06% SO2, the NOx conversion was rapidly reduced and became unrecoverable. Characterizations indicated that the specific surface area of the deactivated catalyst was significantly reduced and the redox ability was weakened, which was highly responsible for the decrease of the catalytic activity. XPS results showed that more Ce3+ was generated in the case of reacting with SO2. In situ DRIFTS results confirmed that the adsorption capacity of SO2 was enhanced obviously in the presence of O2, while the SO2 considerably refrained the adsorption of NH3. The adsorption of NOx was strengthened by SO2 to some extent. In addition, NH3 adsorption was improved after pre-adsorbed by SO2 + O2, indicating that the Ce3+ and more oxygen vacancy were produced.

Promotional mechanism of enhanced denitration activity with Cu modification in a Ce/TiO2–ZrO2 catalyst for a low temperature NH3-SCR system

“…The peaks denoted as u' and v' are assigned to Ce 3+ , while the peaks denoted as u, u'', u''', v, v'' and v''' are attributed to Ce 4+ . 31,32 The existence of Ce 4+ /Ce 3+ redox couple contributes to the better NH 3 -SCR activity of the catalyst. Fig.…”

Decomposition of N2O on ZIF-67-Derived Co/CoOx@Carbon Catalysts and SO2 Interference

“…For a detailed comparison, their corresponding 3D-contour spectra (the adsorption intensity as a function of time, 2400–2100, 1600–1100 cm –1 in detail) are presented in Figure a–c, and the specific discussion is as follows. As SO 2 was injected at 350 °C, a concentrated and strong adsorption zone between 1320 and 1380 cm –1 was observed (Figure A-a). The bands centered at 1372 cm –1 could be ascribed to the asymmetric vibration of OSO groups existing in the form of SO 4 2– , and that centered at 1340 cm –1 could be ascribed to adsorbed SO 2 existing in the form of SO 3 2 . , , However, the bands corresponded to N 2 O at 2240, 2214, and 2195 cm –1 were hardly observed. It suggested that SO 2 adsorbed at low temperature was competitively combined and further reacted with cobalt species, resulting in serious deactivation. As the adsorption temperature increased, several scattered bands were observed (Figure B-b).…”

“…Besides, the bands at ∼1384 cm −1 suggested that a CoOSO 4 intermediate was possibly formed via the reaction of adsorbed SO 2 (SO 3 2− ) with Co−OH at 550 °C, which might further lead to the conversion of CoOSO 4 into SO 3 and Co 2+ species. 69,73 (iii) The bands at 2240, 2214, and 2195 cm −1 were observed at higher temperatures (Figure 13C) but generally lagged behind those caused by SO 2 (Figure 13c). This indicated that the binding capacity of SO 2 to active sites on Co-650N was stronger than that of N 2 O, consistent with the competitive adsorption results at 350 °C.…”

“…The bands centered at 1372 cm −1 could be ascribed to the asymmetric vibration of OSO groups existing in the form of SO 4 2− , and that centered at 1340 cm −1 could be ascribed to adsorbed SO 2 existing in the form of SO 3 2 . 69,7069,70 However, the bands corresponded to N 2 O at 2240, 2214, and 2195 cm −1 were hardly observed. It suggested that SO 2 adsorbed at low temperature was competitively combined and further reacted with cobalt species, resulting in serious deactivation.…”

A Green CeO2−WO3/TiO2 Medium‐Low Temperature de‐NOx Catalyst for Selective Catalytic Reduction of NOx with NH3

“…Catalysts were the core part of SCR reaction, various catalysts have been developed, such as manganese-based catalyst, [5][6][7][8] vanadium-based catalyst, [9][10][11][12] rare earth-based catalyst, [13,14] carbon-based catalyst, [15][16][17] etc. Among them, cerium-based catalysts have gradually become a research hotspot because of the great performance and wide temperature windows.…”