Assessing Guest Diffusion in Nanoporous Materials by Boltzmann's Integration Method

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• 作者：Pavel Kortunov ; Lars Heinke ; Jö ; rg Kä ; rger
• 刊名：Chemistry of Materials
• 出版年：2007
• 出版时间：August 7, 2007
• 年：2007
• 卷：19
• 期：16
• 页码：3917 - 3923
• 全文大小：493K
• 年卷期：v.19,no.16(August 7, 2007)
• ISSN：1520-5002

文摘

With the introduction of interference microscopy to diffusion studies in zeolites, the direct, space-resolved observation of transport diffusion in nanoporous materials has become possible for the firsttime. The method is based on recording transient concentration profiles during molecular uptake or releaseso that the local intracrystalline diffusivities directly result by a microscopic ("differential") applicationof Fick's second law. We show that under certain conditions the thus accessible wealth of informationon the transport characteristics of nanoporous materials may even be surpassed by the application of anintegration method that Ludwig Boltzmann invented more than a century ago and that thus encountersa large new field of application. The procedure is illustrated by discussing its application to the adsorptionprocess of methanol on FER-type zeolite crystallites. The advantages and limitations of the method incomparison with the differential application of Fick's second law are discussed.