Xiong Zhi-Bo, Ning Xing, Zhou Fei, Yang Bin, Tu Yan-Wu, Jin Jing, Lu Wei, Liu Zong-Hao
School of Energy and Power Engineering, University of Shanghai for Science & Technology Shanghai 200093 China
Jiangsu Guoxin Jingjiang Power LTD Jingjiang 214500 China.
RSC Adv. 2018 Jun 14;8(39):21915-21925. doi: 10.1039/c8ra03131b. eCollection 2018 Jun 13.
The influence of the citric acid content on the structural and redox properties of a magnetic iron-cerium-tungsten mixed oxide catalyst prepared through a microwave-assisted citric acid sol-gel method is investigated TG-DTG-DSC, XRD, N adsorption-desorption, XPS, H-TPR and NH-TPD. Additionally, the NH-SCR activity of the magnetic FeCeW- ( = 0.25, 0.5 and 1.0) catalysts are also studied. The results indicate that an increase in citric acid content strengthens the sol-gel reaction between citric acid and metal ions and promotes the formation of the γ-FeO crystallite not α-FeO. Meanwhile, it decreases the BET surface area and pore volume of the catalyst. Furthermore, the surface concentration of iron species on the catalyst is enhanced when the molar ratio of citric acid/(Fe + Ce + W) increases from 0.25 to 1.0, but its surface absorbed oxygen and total oxygen concentration decrease. The magnetic FeCeW-0.5 catalyst shows the best reducibility at temperatures below 790 °C. The increase in the citric acid content inhibits the formation of acid sites in the catalyst, thus the magnetic FeCeW-0.25 catalyst possesses the most Lewis acid sites and Brønsted acid sites among the catalysts. The enhancement in citric acid content is beneficial to improve the SCR reaction rates normalized by the surface area of the catalyst. This catalyst exhibits high anti-SO and HO poisoning, and the molar ratio of citric acid/(Fe + Ce + W) affects the adsorption of NO species on its surface.
研究了柠檬酸含量对通过微波辅助柠檬酸溶胶 - 凝胶法制备的磁性铁 - 铈 - 钨混合氧化物催化剂的结构和氧化还原性能的影响，采用TG - DTG - DSC、XRD、N₂吸附 - 脱附、XPS、H₂ - TPR和NH₃ - TPD等方法。此外，还研究了磁性FeCeW - x（x = 0.25、0.5和1.0）催化剂的NH₃ - SCR活性。结果表明，柠檬酸含量的增加增强了柠檬酸与金属离子之间的溶胶 - 凝胶反应，并促进了γ - Fe₂O₃微晶而非α - Fe₂O₃的形成。同时，它降低了催化剂的BET表面积和孔体积。此外，当柠檬酸/(Fe + Ce + W)的摩尔比从0.25增加到1.0时，催化剂上铁物种的表面浓度增加，但其表面吸附氧和总氧浓度降低。磁性FeCeW - 0.5催化剂在790℃以下显示出最佳的还原性。柠檬酸含量的增加抑制了催化剂中酸性位点的形成，因此磁性FeCeW - 0.25催化剂在这些催化剂中具有最多的路易斯酸位点和布朗斯特酸位点。柠檬酸含量的增加有利于提高以催化剂表面积归一化的SCR反应速率。该催化剂表现出高抗SO₂和H₂O中毒性能，并且柠檬酸/(Fe + Ce + W)的摩尔比影响NOₓ物种在其表面的吸附。
