Insight into the promoting effect of support pretreatment with sulfate acid on selective catalytic reduction performance of CeO2/ZrO2 catalysts.

[Display omitted] In this paper, sulfated ZrO 2 were synthesized via precipitation and impregnation method, and the promoting effects of support sulfation on selective catalytic reduction (SCR) performance of CeO 2 /ZrO 2 catalysts were investigated. The results revealed that sulfated ZrO 2 could significantly enhance the SCR activity of CeO 2 /ZrO 2 catalysts in a wide temperature range. Especially when S/Zr molar ratio was 0.1, CeO 2 /ZrO 2 -0.1S catalyst exhibited a large operating temperature window of 251 ∼ 500 °C and its N 2 selectivity was 100 % in the temperature range of 150 ∼ 500 °C. Moreover, CeO 2 /ZrO 2 -0.1S catalyst possessed a superior low-temperature activity over 0.1S-CeO 2 /ZrO 2 catalyst. After exposing to 100 ppm SO 2 for 15 h, a high NO conversion efficiency of CeO 2 /ZrO 2 -0.1S catalyst (90.7 %) could still be reached. The characterization results indicated that ZrO 2 treated with a proper dosage of sulfate acid was beneficial to enlarge the specific surface area greatly. Sulfated ZrO 2 was also in favor of promoting the transformation of CeO 2 from crystalline state to highly-dispersed amorphous state, and inhibiting the transformation of ZrO 2 from tetragonal to monoclinic phase. It could also enhance the total surface acidity greatly with an increase in both Brønsted acid sites and Lewis acid sites, thus significantly improving NH 3 adsorption on catalyst surface. Besides, the promoting effect of support sulfation on SCR performance of CeO 2 /ZrO 2 catalysts was also related with the enhanced redox property, higher Ce3+/(Ce3++Ce4+) ratio and abundant surface chemisorbed labile oxygen. The in-situ DRIFTS results implied that nitrate species coordinated on the surface of CeO 2 /ZrO 2 -0.1S catalyst could participate in the Selective catalytic reduction with ammonia (NH 3 -SCR) reactions at either medium or high temperature, suggesting that both Eley-Rideal (E-R) and Langmuir-Hinshelwood (L-H) mechanisms might be followed in SCR reactions. [ABSTRACT FROM AUTHOR]