Enhancement of performance and sulfur resistance of ceria-doped V/Sb/Ti by sulfation for selective catalytic reduction of NOx with ammonia
- Enhancement of performance and sulfur resistance of ceria-doped V/Sb/Ti by sulfation for selective catalytic reduction of NOx with ammonia
- 권동욱; 홍성창
- Issue Date
- RSC advances
- VOL 6, NO 2-1181
- A ceria-doped V/Sb/Ti catalyst prepared by sulfation was investigated for the selective catalytic reduction of NOx by NH3. The sulfation treatment was carried out at 250, 300, 400, and 500 degrees C. The properties of the catalysts were studied using physico-chemical analyses, including Brunauer-Emmett-Teller (BET) surface area analysis, X-ray photoelectron spectroscopy (XPS), H-2 temperature-programmed reduction (H-2-TPR), temperature programmed oxidation (TPO), NH3 and NO temperature programmed desorption (TPD), transmission infrared spectra (IR), and thermal gravimetric analysis (TGA). The sulfated catalyst demonstrated increased activity due to the following reasons: (i) total acidity was increased by the formation of SO42--NH4+ on the surface of the catalyst; (ii) fast selective catalytic reduction (SCR) reaction was induced by the production of NO2 through reaction of NO and O-2; (iii) the excellent SCR activity can be attributed to an enhancement in active oxygen species and chemisorption of NH3. The SCR reaction over sulfated CeO2 mainly enhanced the Eley-Rideal mechanism as compared to the V/Sb/Ce/Ti (Fresh). The sulfated catalyst demonstrated the best catalytic activity when sulfation was carried out at 500 degrees C for 1 h. At the same time, SO2 resistance was also observed to be increased. On increasing the sulfation time, further increase in catalytic activity was not observed. In contrast, SO2 resistance was decreased with prolonged sulfation. Sulfated ceria had positive effects on the catalytic activity; however, if formed at higher than appropriate levels, negative effects were observed on SO2 deactivation. When considering the activity and SO2 deactivation for the ceria-doped V/Sb/Ti catalyst, the optimal conditions for sulfation were 500 degrees C for 1 h.
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