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Effects of SO 2 on selective catalytic reduction of NO with NH 3 over a TiO 2 photocatalyst

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ABSTRACT

The effect of SO2 gas was investigated on the activity of the photo-assisted selective catalytic reduction of nitrogen monoxide (NO) with ammonia (NH3) over a TiO2 photocatalyst in the presence of excess oxygen (photo-SCR). The introduction of SO2 (300 ppm) greatly decreased the activity of the photo-SCR at 373 K. The increment of the reaction temperature enhanced the resistance to SO2 gas, and at 553 K the conversion of NO was stable for at least 300 min of the reaction. X-ray diffraction, FTIR spectroscopy, thermogravimetry and differential thermal analysis, x-ray photoelectron spectroscopy (XPS), elemental analysis and N2 adsorption measurement revealed that the ammonium sulfate species were generated after the reaction. There was a strong negative correlation between the deposition amount of the ammonium sulfate species and the specific surface area. Based on the above relationship, we concluded that the deposition of the ammonium sulfate species decreased the specific surface area by plugging the pore structure of the catalyst, and the decrease of the specific surface area resulted in the deactivation of the catalyst.

No MeSH data available.


XP spectra of (A) S 2p, (B) N 1s, (C) Ti 2p and (D) O 1s of the catalysts. (a) BR, (b) AR-373K, (c) AR-433K and (d) AR-533K. Patterns are offset for clarity.
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Figure 5: XP spectra of (A) S 2p, (B) N 1s, (C) Ti 2p and (D) O 1s of the catalysts. (a) BR, (b) AR-373K, (c) AR-433K and (d) AR-533K. Patterns are offset for clarity.

Mentions: In the S 2p XP spectra of BR (figure 5(A)), no band was observed in the range of 165–175 eV. In all the catalysts after the reaction, asymmetric bands were observed at the peak position of 168.6–168.8 eV. The asymmetry of the bands is because of the overlap of the split sublevels of the 2p3/2 and 2p1/2 states of S atoms (separation of bands: 1.2 eV) by spin–orbit coupling [23]. The spectra of the catalysts after the reaction were reasonably fitted using two Gaussian functions (figure S3 in the supplementary data and table S1). In all the catalysts after the reaction, the peak positions were 168.5–168.6 and 169.7–169.9 eV, which corresponded to the peak positions of S 2p3/2 and S 2p1/2 of the sulfate ( species, respectively [20]. The ratios of the peak areas of S 2p3/2 to those of S 2p1/2 were 1.96–1.99 in all the catalysts after the reaction, and the values were in good agreement with the theoretical value of 2. The FWHM of the each peak was the same in all the catalysts (about 1.6 eV), which suggests that the S 2p XP spectra of the catalysts are derived from a single sulfur species of (S6+).


Effects of SO 2 on selective catalytic reduction of NO with NH 3 over a TiO 2 photocatalyst
XP spectra of (A) S 2p, (B) N 1s, (C) Ti 2p and (D) O 1s of the catalysts. (a) BR, (b) AR-373K, (c) AR-433K and (d) AR-533K. Patterns are offset for clarity.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Figure 5: XP spectra of (A) S 2p, (B) N 1s, (C) Ti 2p and (D) O 1s of the catalysts. (a) BR, (b) AR-373K, (c) AR-433K and (d) AR-533K. Patterns are offset for clarity.
Mentions: In the S 2p XP spectra of BR (figure 5(A)), no band was observed in the range of 165–175 eV. In all the catalysts after the reaction, asymmetric bands were observed at the peak position of 168.6–168.8 eV. The asymmetry of the bands is because of the overlap of the split sublevels of the 2p3/2 and 2p1/2 states of S atoms (separation of bands: 1.2 eV) by spin–orbit coupling [23]. The spectra of the catalysts after the reaction were reasonably fitted using two Gaussian functions (figure S3 in the supplementary data and table S1). In all the catalysts after the reaction, the peak positions were 168.5–168.6 and 169.7–169.9 eV, which corresponded to the peak positions of S 2p3/2 and S 2p1/2 of the sulfate ( species, respectively [20]. The ratios of the peak areas of S 2p3/2 to those of S 2p1/2 were 1.96–1.99 in all the catalysts after the reaction, and the values were in good agreement with the theoretical value of 2. The FWHM of the each peak was the same in all the catalysts (about 1.6 eV), which suggests that the S 2p XP spectra of the catalysts are derived from a single sulfur species of (S6+).

View Article: PubMed Central - PubMed

ABSTRACT

The effect of SO2 gas was investigated on the activity of the photo-assisted selective catalytic reduction of nitrogen monoxide (NO) with ammonia (NH3) over a TiO2 photocatalyst in the presence of excess oxygen (photo-SCR). The introduction of SO2 (300 ppm) greatly decreased the activity of the photo-SCR at 373 K. The increment of the reaction temperature enhanced the resistance to SO2 gas, and at 553 K the conversion of NO was stable for at least 300 min of the reaction. X-ray diffraction, FTIR spectroscopy, thermogravimetry and differential thermal analysis, x-ray photoelectron spectroscopy (XPS), elemental analysis and N2 adsorption measurement revealed that the ammonium sulfate species were generated after the reaction. There was a strong negative correlation between the deposition amount of the ammonium sulfate species and the specific surface area. Based on the above relationship, we concluded that the deposition of the ammonium sulfate species decreased the specific surface area by plugging the pore structure of the catalyst, and the decrease of the specific surface area resulted in the deactivation of the catalyst.

No MeSH data available.