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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.


Effect of the Stot estimated by the V–t plots on the conversion of NO after 300 min of the photo-SCR at various temperatures.
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Figure 8: Effect of the Stot estimated by the V–t plots on the conversion of NO after 300 min of the photo-SCR at various temperatures.

Mentions: The amount of the (NH4)2SO4 species decreased with increasing the reaction temperature. Figures 7(A) and (B) show a correlation between the Stot and the contents of N and S estimated by the EA. The increment of the contents of S and N drastically decreased the Stot. FTIR analysis revealed two species: one is the (NH4)2SO4 species and the other is the surface-coordinated species. The negative linear correlation for the N content strongly suggests that the decrease of the Stot is not because of the generation of the surface-coordinated species but is because of the bulk (NH4)2SO4 species. The conversion of NO after 300 min of the reaction was plotted vs. the Stot (figure 8). The strong positive and linear correlation was obtained, which indicates that the decrease of the Stot results in the decrease of the conversion of NO. Based on the above discussion, we concluded that the generation of the (NH4)2SO4 species plugged a part of the mesopores derived from the gap between the TiO2 particles, which resulted in the decrease of the Stot and the deactivation of the catalyst.


Effects of SO 2 on selective catalytic reduction of NO with NH 3 over a TiO 2 photocatalyst
Effect of the Stot estimated by the V–t plots on the conversion of NO after 300 min of the photo-SCR at various temperatures.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 8: Effect of the Stot estimated by the V–t plots on the conversion of NO after 300 min of the photo-SCR at various temperatures.
Mentions: The amount of the (NH4)2SO4 species decreased with increasing the reaction temperature. Figures 7(A) and (B) show a correlation between the Stot and the contents of N and S estimated by the EA. The increment of the contents of S and N drastically decreased the Stot. FTIR analysis revealed two species: one is the (NH4)2SO4 species and the other is the surface-coordinated species. The negative linear correlation for the N content strongly suggests that the decrease of the Stot is not because of the generation of the surface-coordinated species but is because of the bulk (NH4)2SO4 species. The conversion of NO after 300 min of the reaction was plotted vs. the Stot (figure 8). The strong positive and linear correlation was obtained, which indicates that the decrease of the Stot results in the decrease of the conversion of NO. Based on the above discussion, we concluded that the generation of the (NH4)2SO4 species plugged a part of the mesopores derived from the gap between the TiO2 particles, which resulted in the decrease of the Stot and the deactivation of the catalyst.

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.