Physical adsorption characterization of nanoporous materials: progress and challenges
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Physical adsorption characterization of nanoporous materials: progress and challenges Matthias Thommes • Katie A. Cychosz
Received: 13 November 2013 / Revised: 25 January 2014 / Accepted: 28 January 2014 / Published online: 19 February 2014 Springer Science+Business Media New York 2014
Abstract Within the last two decades major progress has been achieved in understanding the adsorption and phase behavior of fluids in ordered nanoporous materials and in the development of advanced approaches based on statistical mechanics such as molecular simulation and density functional theory (DFT) of inhomogeneous fluids. This progress, coupled with the availability of high resolution experimental procedures for the adsorption of various subcritical fluids, has led to advances in the structural characterization by physical adsorption. It was demonstrated that the application of DFT based methods on high resolution experimental adsorption isotherms provides a much more accurate and comprehensive pore size analysis compared to classical, macroscopic methods. This article discusses important aspects of major underlying mechanisms associated with adsorption, pore condensation and hysteresis behavior in nanoporous solids. We discuss selected examples of state-of-the-art pore size characterization and also reflect briefly on the existing challenges in physical adsorption characterization. Keywords Physical adsorption Argon 87 K adsorption Pore condensation Hysteresis DFT pore size distribution Hierarchically structured materials
M. Thommes (&) K. A. Cychosz Quantachrome Instruments, 1900 Corporate Dr, Boynton Beach, FL 33426, USA e-mail: [email protected]
1 Introduction Major progress has been made in recent years concerning the synthesis of nanoporous materials with tailored pore size and structure, controlled surface functionality, and their applications (e.g. for reviews see: Barton et al. 1999; Roth and Vartuli 2005; Zhao and Wang 2007; Hoffmann et al. 2006; Kleitz 2008; Hartmann and Jung 2010; Kresge and Roth 2013). Advances have also been made in the development and structural characterization of micro- and mesoporous materials such as mesoporous zeolites and hierarchically organized pore structures with an appropriate balance of micropores, mesopores, and macropores, the latter being required to ensure the transport of fluids to and from the smaller pores at a satisfactory rate (e.g. Mintova and Cejka 2007; Serrano et al. 2009; Na et al. 2011; Mo¨ller and Bein 2011; Pe´rez-Ramı´rez et al. 2011; Zhang et al. 2012; Li et al. 2013; Valiullin and Kaerger 2011). Recently, the synthesis of a novel class of alumina/silica transition metal based materials has been reported, which have pores between 1 and 2 nm, i.e. these novel materials bridge between zeolites and M41S materials (Shpeizer et al. 2006, 2010). A major point of interest are metal– organic framework materials (MOFs) and related nanoporous materials which offer a wide range of potential applications such as gas storage, separation, catalysis
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