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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.


Deposition model of sulfate species of the catalysts.
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Figure 6: Deposition model of sulfate species of the catalysts.

Mentions: N2 adsorption/desorption experiments revealed the decrease of the Stot after the reaction, which was mainly due to the decrease of the Sint. The decrease of the Sint is not due to the aggregation of the TiO2 particles during the reaction because the crystalline size of the TiO2 particles did not change after the reaction (table 1). FTIR, TG-DTA, XPS and EA revealed the generation of the bulk (NH4)2SO4 species on the TiO2 surface after the reaction. The amount of (NH4)2SO4 in AR-373K, which contains the largest amount of S and N atoms among the three catalysts after the reaction, is calculated to be 12 wt% assuming that all the N atoms, which were estimated by EA, exist in the (NH4)2SO4 form. However, the XRD diffraction peak of the bulk (NH4)2SO4 species was not observed in AR-373K, which implies that the generated bulk (NH4)2SO4 species has an amorphous structure. Thus, the generated bulk (NH4)2SO4 species plugged the pores of the catalysts, which resulted in the decrease of the Sint (figure 6).


Effects of SO 2 on selective catalytic reduction of NO with NH 3 over a TiO 2 photocatalyst
Deposition model of sulfate species of the catalysts.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC5036466&req=5

Figure 6: Deposition model of sulfate species of the catalysts.
Mentions: N2 adsorption/desorption experiments revealed the decrease of the Stot after the reaction, which was mainly due to the decrease of the Sint. The decrease of the Sint is not due to the aggregation of the TiO2 particles during the reaction because the crystalline size of the TiO2 particles did not change after the reaction (table 1). FTIR, TG-DTA, XPS and EA revealed the generation of the bulk (NH4)2SO4 species on the TiO2 surface after the reaction. The amount of (NH4)2SO4 in AR-373K, which contains the largest amount of S and N atoms among the three catalysts after the reaction, is calculated to be 12 wt% assuming that all the N atoms, which were estimated by EA, exist in the (NH4)2SO4 form. However, the XRD diffraction peak of the bulk (NH4)2SO4 species was not observed in AR-373K, which implies that the generated bulk (NH4)2SO4 species has an amorphous structure. Thus, the generated bulk (NH4)2SO4 species plugged the pores of the catalysts, which resulted in the decrease of the Sint (figure 6).

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.