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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.


(A) TG profiles, (B) DTA profiles and (C) derivative thermogravimetry (DTG) profiles of the catalysts and the reference samples. (a) BR, (b) AR-373K, (c) AR-433K, (d) AR-533K, (e) (NH4)2SO4 and (f) physical mixture of (NH4)2SO4 and TiO2 ((NH4)2SO4: 10% by weight).
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Figure 4: (A) TG profiles, (B) DTA profiles and (C) derivative thermogravimetry (DTG) profiles of the catalysts and the reference samples. (a) BR, (b) AR-373K, (c) AR-433K, (d) AR-533K, (e) (NH4)2SO4 and (f) physical mixture of (NH4)2SO4 and TiO2 ((NH4)2SO4: 10% by weight).

Mentions: TG profiles of the catalysts are shown in figure 4(A). Several steps of the weight loss were observed in all the catalysts after the reaction, although the TiO2 has only one step of the weight loss around 330 K. From room temperature to 1173 K, the weights of BR, AR-373K, AR-433K and AR-553K decreased by 3.9, 16.1, 12.5 and 8.1%, respectively. Figure 4(B) shows the DTA profiles of the catalysts. All the profiles had a strong exothermic band around 1150 K without the weight loss, which was derived from the phase transition of TiO2 from anatase to rutile. In the DTA profile of BR (see the inset of figure 4(B)), a broad exothermic band was observed around 820 K without the weight loss. The peak was observed in all the catalysts before and after the reaction and was possibly due to the crystallization of TiO2 [21]. In addition, other exothermic bands were observed around 500 and 700 K in the case of the catalysts after the reaction.


Effects of SO 2 on selective catalytic reduction of NO with NH 3 over a TiO 2 photocatalyst
(A) TG profiles, (B) DTA profiles and (C) derivative thermogravimetry (DTG) profiles of the catalysts and the reference samples. (a) BR, (b) AR-373K, (c) AR-433K, (d) AR-533K, (e) (NH4)2SO4 and (f) physical mixture of (NH4)2SO4 and TiO2 ((NH4)2SO4: 10% by weight).
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
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Figure 4: (A) TG profiles, (B) DTA profiles and (C) derivative thermogravimetry (DTG) profiles of the catalysts and the reference samples. (a) BR, (b) AR-373K, (c) AR-433K, (d) AR-533K, (e) (NH4)2SO4 and (f) physical mixture of (NH4)2SO4 and TiO2 ((NH4)2SO4: 10% by weight).
Mentions: TG profiles of the catalysts are shown in figure 4(A). Several steps of the weight loss were observed in all the catalysts after the reaction, although the TiO2 has only one step of the weight loss around 330 K. From room temperature to 1173 K, the weights of BR, AR-373K, AR-433K and AR-553K decreased by 3.9, 16.1, 12.5 and 8.1%, respectively. Figure 4(B) shows the DTA profiles of the catalysts. All the profiles had a strong exothermic band around 1150 K without the weight loss, which was derived from the phase transition of TiO2 from anatase to rutile. In the DTA profile of BR (see the inset of figure 4(B)), a broad exothermic band was observed around 820 K without the weight loss. The peak was observed in all the catalysts before and after the reaction and was possibly due to the crystallization of TiO2 [21]. In addition, other exothermic bands were observed around 500 and 700 K in the case of the catalysts after the reaction.

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.