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	担体酸性对铂催化剂的表面性质和催化性能的电子调变效应; THE ELECTRONIC MODIFICATION EFFECT OF ACIDITY OF SUPPORT UPON THE SURFACE PROPERTIES AND CATALYTIC BEHAVIORS OF SUPPORTED Pt CATALYSTS
	王录平 ; 杨锡尧 ; 庞礼
	1986
关键词	铂催化剂 调变 表面性质 担体 酸强度 加氢活性 电子效应 催化剂组成 程序升温脱附 吸电子
英文摘要	采用红外光谱法、竞争加氢反应法和程序升温脱附法等研究三种具有不同酸性的载体—γ-Al_2O_3,Al_2O_3-SiO_2和HY分子筛与铂的相互作用,结果表明载体的酸性部位对铂原子具有吸电子作用,使铂原子表现为缺电子状态;酸性部位的酸强度越大吸电子的能力越强。酸性部位的这种电子效应使铂催化剂的甲苯加氢活性和抗硫中毒性能都增强。; The electronic effect of acidity of supports upon the surface properties and catalytic behaviors of various supported Pt catalysts have been studied by IR spectroscopy, competitive hydrogenation reaction, TPD method and hydrogenation of toluene as test reaction. The supports used are HY zeolite, Al2O3-SiO2, gamma-Al2O3 etc; Number of acid site and acid strength of supports determined by n-butylamine titration method follow the sequence, for number of acid site, HY>Al2O3-SiO2>gamma-Al2O3 for acid strength, HY>Al2O3-SiO2>gamma-Al2O3 The adsorption band frequencies of CO adsorbed on catalysts, nu((00)) (cm(-1)) are as follows, Pt/HY 2068, Pt/Al2O3-SiO2 2062, Pt/gamma-Al2O3 2058, It is obvious that nu((co)) increases with the acid strength of support; This means that acid sites of support act as electron. acceptor, inducing art additional electron-deficiency of Pt atoms, so that the larger the acid strength cif support the larger the nu((co)) value. The electronic effect of acid sites has been testified too by competitive hydrogenation reaction method, The values of adsorption coefficient ratio of toluene to benzene, K-T/B are as follows, Pt/HY 15.7, Pt/Al2O3-SiO2 Pt/gamma-Al2O3 5, 1, It is shown that K-T/B value increases with the acid strength of support, This indicates that the additional electron-deficiency of Pt atoms increases with the acid strength of support, The results agree well with those of IR determination. In addition, the catalytic behaviors of catalysts are greatly modified by the acid strength of support, namely, the activity for hydrogenation of toluene and resistance to sulfur deactivation of catalysts increase with the strength of support. Comparing the results of IR and competitive hydrogenation reaction investigation with those of hydrogenation of toluene, we might conclude that the increase of additional electron deficiency of Pt atoms, being induced by acid sites, causes the enhancement of catalytic activity and resistance to sulfur deactivation of catalyst. Owing to the electron deficient character of Pt atoms, toluene are adsorbed and activated more strongly and this might he the reason why the catalytic activity of catalyst enhances with the increase of acid strength of support Moreover, it has been shown that adsorbed sulfur species which cause the deactivation of catalyst act as an electron acceptor([10]). As shown above, for supported Pt Catalyst, acid sites of support act as an electron acceptor too. Thererfore, owing to the competition of interaction for Pt atoms between sulfur species sad acid sitits, the adsorption ability of sulfur species on Pt atoms becomes smelter, and so the res resistance to sulfur deactivation of catalyst beverage larger. The TPD profiles of catalysts which preadsorbed by sulfur show that. for Pt/Al2O3-SiO2, and Pt/HY, there are a number of adsortion sites remain unpoisoned from sulfur, These results confirm Cat the acid sites really posses the action to weaken the adsorption ability If sulfur on Pt atoms. On the basis of the results given above, it can be concluded that the acid sites of support in catalyst act as electron acceptor, inducing an additional electron deficiency of Pt atoms, which causes the enhancement of catalytic activity and resistance to sulfur deactivation of catalysts,; http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000207568700006&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701 ; SCI(E); 0; 05; 424-431; 2
语种	中文
出处	知网 ; SCI
出版者	物理化学学报
内容类型	其他
源URL	[http://hdl.handle.net/20.500.11897/78681]
专题	化学与分子工程学院
推荐引用方式 GB/T 7714	王录平,杨锡尧,庞礼. 担体酸性对铂催化剂的表面性质和催化性能的电子调变效应, THE ELECTRONIC MODIFICATION EFFECT OF ACIDITY OF SUPPORT UPON THE SURFACE PROPERTIES AND CATALYTIC BEHAVIORS OF SUPPORTED Pt CATALYSTS. 1986-01-01.

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