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摘要: 富氧条件下具有FAU和BEA两种拓扑结构的CoH-FBZ选择催化CH4还原NO,显示出较CoHY和CoHBeta机械混合催化剂更好的催化活性。应用吸附和程序升温脱附(TPD)方法研究了NO和NO+O2与催化剂表面间的相互作用。结果表明,载体的拓扑结构直接影响N、O物种在催化剂表面的稳定性。NO与O2在CoH-FBZ表面形成的吸附态NOy及NO在CoH-FBZ表面形成的吸附态相对更稳定。CoH-FBZ的NO+O2-TPD脱附曲线在630K和660K形成两个NO2脱附峰,表明在CoH-FBZ表面形成了新的NOy吸附中心,即可能有新的Co位产生,该新Co位与沸石催化剂CoH-FBZ中新强酸位协同作用,使CoH-FBZ表现出新的CH4-SCR催化特性。Abstract: Selective catalytic reduction of NO by methane in the presence of excess oxygen over CoH-FBZ zeolite composite catalyst has an advantage over the physical mixture of CoH-Y and CoH-Beta. The interaction between NO or NO+O2 and the catalyst revealed by adsorption and temperatureprogrammed desorption (TPD) technique, results directly in the effect of the topological structure of supports upon the stability of N-and O-species on the surface of the catalysts. The NO+O2-TPD profile of the CoH-FBZ catalyst exhibits two NO2 desorption peaks at 630K and 660K, respectively. This indicates that new adsorption centers for-NOy are formed over the CoH-FBZ and adsorbed more stably on CoH-FBZ than on CoH-Y or CoH-Beta, NO does in a similar manner. The synergism of the newly formed Co sites and the new strong acidic sites contributes to the novel CH4-SCR catalytic properties of the CoH-FBZ catalysts.
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Key words:
- selective catalytic reduction /
- NO /
- CH4 /
- temperature-programmed desorption /
- CoH-FBZ
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