{"title":"XPS study of Pt ammine decomposition in K faujasites: Comparison with bulk behavior","authors":"Z. Bastl, L. Kubelková, J. Nováková","doi":"10.1016/S0144-2449(97)00066-3","DOIUrl":null,"url":null,"abstract":"<div><p>The XPS method is employed to compare the behavior of [Pt(NH<sub>3</sub>)<sub>4</sub>]<sup>2+</sup> ions in the surface layers of KX and KY zeolites with that in the zeolite bulk. <em>FT</em> i.r. and MS-t.p.d. methods are used to characterize the bulk properties. XPS and <em>FT</em> i.r. reveal the formation of different intermediate NH<em><sub>x</sub></em> species during the decomposition of the ammine complex in a vacuum. They are interpreted as Pt-diammine, framework ammine, and immine complexes. The maximum evolution of ammonia occurs in the temperature interval ranging from 150°C to 250°C. Positive shifts of Pt: (4f) photoelectrons, observed for samples with a decomposed Pt-ammine complex, are explained by a decrease of the population of Pt 5d levels in encaged metallic clusters. The surface concentration of Pt decreases with increasing temperature due to the inward diffusion of Pt atoms.</p></div>","PeriodicalId":23983,"journal":{"name":"Zeolites","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"1997-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0144-2449(97)00066-3","citationCount":"4","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Zeolites","FirstCategoryId":"1085","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0144244997000663","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 4
Abstract
The XPS method is employed to compare the behavior of [Pt(NH3)4]2+ ions in the surface layers of KX and KY zeolites with that in the zeolite bulk. FT i.r. and MS-t.p.d. methods are used to characterize the bulk properties. XPS and FT i.r. reveal the formation of different intermediate NHx species during the decomposition of the ammine complex in a vacuum. They are interpreted as Pt-diammine, framework ammine, and immine complexes. The maximum evolution of ammonia occurs in the temperature interval ranging from 150°C to 250°C. Positive shifts of Pt: (4f) photoelectrons, observed for samples with a decomposed Pt-ammine complex, are explained by a decrease of the population of Pt 5d levels in encaged metallic clusters. The surface concentration of Pt decreases with increasing temperature due to the inward diffusion of Pt atoms.
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