在选择催化还原(selective catalytic reduction,SCR)反应中,SO_2对脱硝催化剂活性具有重要影响.通过浸渍法制备的金属有机骨架(metal-organic frameworks,MOFs)MIL-100(Fe)(materials of Institute Lavoisier,MIL)担载CeO_2的CeO_2/MIL...在选择催化还原(selective catalytic reduction,SCR)反应中,SO_2对脱硝催化剂活性具有重要影响.通过浸渍法制备的金属有机骨架(metal-organic frameworks,MOFs)MIL-100(Fe)(materials of Institute Lavoisier,MIL)担载CeO_2的CeO_2/MIL-100(Fe)催化剂在250℃含有500×10^(-6) SO_2的条件下,对NO_x转化率在10h内可以稳定在91%以上,高于MIL-100(Fe)催化剂的83%.原位红外漫反射傅里叶变换谱实验结果表明,SO2会导致MIL-100(Fe)催化剂表面B酸性位上NH_4^+物种的吸附强度降低,由此导致了含硫SCR反应中NO_x转化率下降.CeO_2/MIL-100(Fe)催化剂中由于添加了CeO_2,有效地减弱了SO2对催化剂表面B酸性位上NH_4^+物种吸附强度的影响,提高了含硫条件下NO_x的转化率,增强了复合催化剂在SCR反应中的抗硫性能.展开更多
Ceria-based catalytic materials are known for their crystal-face-dependent catalytic properties.To obtain a molecular-level understanding of their surface chemistry,controlled synthesis of ceria with well-defined surf...Ceria-based catalytic materials are known for their crystal-face-dependent catalytic properties.To obtain a molecular-level understanding of their surface chemistry,controlled synthesis of ceria with well-defined surface structures is required.We have thus studied the growth of CeOx nanostructures(NSs)and thin films on Pt(111).The strong metal-oxide interaction has often been invoked to explain catalytic processes over the Pt/CeOx catalysts.However,the Pt-CeOx interaction has not been understood at the atomic level.We show here that the interfacial interaction between Pt and ceria could indeed affect the surface structures of ceria,which could subsequently determine their catalytic chemistry.While ceria on Pt(111)typically exposes the CeO2(111)surface,we found that the structures of ceria layers with a thickness of three layers or less are highly dynamic and dependent on the annealing temperatures,owing to the electronic interaction between Pt and CeOx.A two-step kinetically limited growth procedure was used to prepare the ceria film that fully covers the Pt(111)substrate.For a ceria film of^3–4 monolayer(ML)thickness on Pt(111),annealing in ultrahigh vacuum(UHV)at 1000 K results in a surface of CeO2(100),stabilized by a c-Ce2O3(100)buffer layer.Further oxidation at 900 K transforms the surface of the CeO2(100)thin film into a hexagonal CeO2(111)surface.展开更多
文摘在选择催化还原(selective catalytic reduction,SCR)反应中,SO_2对脱硝催化剂活性具有重要影响.通过浸渍法制备的金属有机骨架(metal-organic frameworks,MOFs)MIL-100(Fe)(materials of Institute Lavoisier,MIL)担载CeO_2的CeO_2/MIL-100(Fe)催化剂在250℃含有500×10^(-6) SO_2的条件下,对NO_x转化率在10h内可以稳定在91%以上,高于MIL-100(Fe)催化剂的83%.原位红外漫反射傅里叶变换谱实验结果表明,SO2会导致MIL-100(Fe)催化剂表面B酸性位上NH_4^+物种的吸附强度降低,由此导致了含硫SCR反应中NO_x转化率下降.CeO_2/MIL-100(Fe)催化剂中由于添加了CeO_2,有效地减弱了SO2对催化剂表面B酸性位上NH_4^+物种吸附强度的影响,提高了含硫条件下NO_x的转化率,增强了复合催化剂在SCR反应中的抗硫性能.
基金supported by the National Key R&D Program of China(2017YFB0602205,2016YFA0202803,2017YFA0303104)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB17020200)the National Natural Science Foundation of China(21473191,91545204)~~
文摘Ceria-based catalytic materials are known for their crystal-face-dependent catalytic properties.To obtain a molecular-level understanding of their surface chemistry,controlled synthesis of ceria with well-defined surface structures is required.We have thus studied the growth of CeOx nanostructures(NSs)and thin films on Pt(111).The strong metal-oxide interaction has often been invoked to explain catalytic processes over the Pt/CeOx catalysts.However,the Pt-CeOx interaction has not been understood at the atomic level.We show here that the interfacial interaction between Pt and ceria could indeed affect the surface structures of ceria,which could subsequently determine their catalytic chemistry.While ceria on Pt(111)typically exposes the CeO2(111)surface,we found that the structures of ceria layers with a thickness of three layers or less are highly dynamic and dependent on the annealing temperatures,owing to the electronic interaction between Pt and CeOx.A two-step kinetically limited growth procedure was used to prepare the ceria film that fully covers the Pt(111)substrate.For a ceria film of^3–4 monolayer(ML)thickness on Pt(111),annealing in ultrahigh vacuum(UHV)at 1000 K results in a surface of CeO2(100),stabilized by a c-Ce2O3(100)buffer layer.Further oxidation at 900 K transforms the surface of the CeO2(100)thin film into a hexagonal CeO2(111)surface.
