Counterdiffusion of p-Xylene/Benzene and p-Xylene/o-Xylene in Silicalite Studied by the Zero-Length Column Technique

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• 作者：Stefano Brandani ; Mohamad Jama ; and Douglas M. Ruthven
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2000
• 出版时间：March 2000
• 年：2000
• 卷：39
• 期：3
• 页码：821 - 828
• 全文大小：158K
• 年卷期：v.39,no.3(March 2000)
• ISSN：1520-5045

文摘

This paper describes the extension of the zero-length column (ZLC) method of measuringintracrystalline diffusion to the study of counterdiffusion. Theoretical ZLC response curves arederived for two simple models considering chemical potential gradient as the driving force fortransport with the intrinsic mobilities either constant or inversely dependent on total loading.Experimental response curves for benzene-p-xylene and p-xylene-benzene in silicalite are shownto be consistent with the first of these models. The response curves conform quantitatively tothe response predicted from this model using the measured pure component diffusivities.However, the behavior of the benzene-o-xylene and p-xylene-o-xylene systems does not conformto the simple model. The retardation caused by o-xylene is substantially greater than thatpredicted from the single-component diffusivity data. A simple microdynamic explanation issuggested to account for this apparent anomaly.