Abstract
Pulsed Field Gradient (PFG) NMR is applied to study molecular diffusion of benzene in a commercial sample of MCM-41. Over a very small concentration range at medium pore filling factors the diffusivity is found to sharply drop by up to one order of magnitude, while it remains essentially constant over the total remaining range from vanishing concentrations up to over-saturation. Similarly extreme deviations from monotonous concentration patterns have so far not been described in the literature. The observed effect may be rationalised as a consequence of the onset of capillary condensation in the transport pores in the hyper-structure of the MCM-41 particles under study.
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B¨ ar, N.-K., J. K¨ arger, C. Krause, W. Schmitz, and G. Seiffert, “Pitfalls in PFG NMR Self-Diffusion Measurements with Powder Samples,” J. Magn. Reson. A, 113, 278–280(1995).
Beck, J.S., J.C. Vartuli, W.J. Roth, M.E. Leonowicz, C.T. Kresge, K.D. Schmitt, C.T.-W. Chu, D.H. Olson, E.W. Sheppard, S.B. McCullen, J.B. Higgins, and J.L. Schlenker, “A New Family of Mesoporous Molecular Sieves Prepared with Liquid Crystal Tem-plates,” J. Am. Chem. Soc., 114, 10834–10854(1992).
Bonneviot, L., S. Giasson, S. Kaliaguine, and M. St¨ocker (Eds.), in Proceedings of the 2nd International Symposium on Mesoporous Molecular Sieves (ISMMS), Quebec City, Canada, 2000, Micropor. Mesopor. Mater., 44/45,v–xi (2001).
B¨ ulow, M. and A. Micke, “Determination of Transport Coefficients in Microporous Solids,” Adsorption, 1,29–48(1995).
Cotts, R.M., M.J.R. Hoch, T. Sun, and J.T. Markert, “Pulsed Field Gradient Stimulated Echo Methods for Improved NMR Diffusion Measurements in Heterogeneous Systems,” J. Magn. Reson., 83, 252–266(1989).
Courivaud, F., E.W. Hansen, A. Karlsson, S. Kolboe, and M. Stocker, “Pulsed Field Gradient NMR Study of the Diffusion of n-Hexane Confined in Hydroxylated and Dehydroxylated MCM-41 of Various Pore Diameters,” Micropor. Mesopor. Mater., 35/36, 327–339 (2000a).
Courivaud, F., E.W. Hansen, S. Kolboe, A. Karlsson, and M. Stocker, “Enhanced n-hexane Diffusion in Partially Filled MCM-41 of Dif-ferent Surface Hydrophobicity Probed by NMR,” Micropor. Mesopor. Mater., 37, 223–232(2000b).
Galvosas, P., F. Stallmach, G. Seiffert, J. K¨arger, U. Kaess, and G. Majer, “Generation and Application of Ultra-High-Intensity Mag-netic Field Gradient Pulses for NMR Spectroscopy,” J. Magn. Reson., 151, 260–268(2001).
Hansen, E.W., F. Courivaud, A. Karlsson, S. Kolboe, and M. Stocker, “Effect of Pore Dimension and Pore Surface Hydrophobicity on the Diffusion of n-Hexane Confined in Mesoporous MCM-41 Probed by NMR—A Preliminary Investigation,” Micropor. Mesopor. Mater., 22, 309–320(1998).
K¨ arger, J., “On the Compatibility of Diffusion Data for Adsorbate-Adsorbent Systems Obtained from NMR Pulsed Field Gradient Technique and from Quasi-Elastic Neutron Scattering,” Mol. Phys., 43, 1189–1191(1981).
K¨arger, J. and D.M. Ruthven, Diffusion in Zeolites and Other Microporous Solids, Wiley-Interscience, New York, 1992.
K¨ arger, J., C. Krause, and H. Sch¨ afer, “A PFG NMR Study of the Channel Structure of Porous Materials,” GIT Spezial, Chro-matographie, 1,26–28(1997).
K¨ arger, J., G. Fleischer, and U. Roland, “PFG NMR Studies of Anomalous Diffusion,” in Diffusion in Condensed Matter, J.
K¨ arger, P. Heitjans, and R. Haberlandt (Eds.), pp. 144–168, Vieweg, Braunschweig/Wiesbaden, 1998a.
K¨ arger, J., C. Krause, and H. Sch¨ afer, “Structure Analysis of Nanoporous Materials by PFG NMR Diffusion Measurement,” Fortschritt-Ber. VDI, R.3, Nr. 555, 104–119(1998b).
Matthae, F.P., W.D. Basler, and H. Lechert, “NMR Relaxation and Self-Diffusion Measurements on Small Molecules in MCM-41 with Different Pore Size,” in Mesoporous Molecular Sieves 1998, L. Bounneviot, F. B´ eland, C. Danumah, S. Giasson, and S. Kaliaguine (Eds.), Studies in Surface Science and Catalysis 117, pp. 301–308, Elsevier, Amsterdam, 1998.
Pophal, C. and H. Fuess, “Investigation of the Medium Range Order of Polyhedra Forming the Walls of MCM-41—An X-Ray Diffraction Study,” Micropor. Mesopor. Mater., 33, 241–247(1999).
Rees, L.V.C. and D.H. Shen, “Frequency-Response Measure-ments of Diffusion of Xenon in Silicalite-1,” J. Chem. Soc. Faraday Trans. I, 86, 3687–3692(1990).
Ruthven, D.M., Principles of Adsorption and Adsorption Processes, Wiley-Interscience, New York, 1984.
Ruthven, D.M. and S. Brandani, “Measurement of Diffusion in Porous Solids by Zero Length Column (ZLC) Methods,” in Recent Advances in Gas Separation by Microporous Materials, N.N. Kanellopoulos (Ed.), pp. 187–212, Elsevier, Amsterdam, 2000.
Spange, S., A. Gr¨ aser, A. Huwe, F. Kremer, C. Tintemann, and P. Behrens, “Cationic Host-Guest Polymerization of N-Vinylcarbazole and Vinyl Ethers in MCM-41, MCM-48, and Nanoporous Glasses,” Chem. Eur. J., 7, 3722–3728(2001).
Spange, S., A. Gr¨ aser, H. M¨ uller, Y. Zimmermann, P. Rehak, C. J¨ ager, H. Fuess, and C. Baehtz, “Synthesis of Inorganic/Organic Host-Guest Hybrid Materials by Cationic Vinyl Polymerization within Y Zeolites and MCM-41,” Chem. Mater., 13, 3698–3708(2001).
Spange, S., Y. Zimmermann, and A. Gr¨ aser, “Hydrogen-Bond-Donating Acidity and Dipolarity/Polarizability of Surfaces within Silica Gels and Mesoporous MCM-41 Materials,” Chem. Mater., 11, 3245–3251(1999).
Stallmach, F., A. Gr¨ aser, J. K¨ arger, C. Krause, M. Jeschke, U. Ober-hagemann, and S. Spange, “Pulsed Field Gradient NMR Studies of Diffusion in MCM-41 Mesoporous Solids,” Microp. Mesop. Mat., 44/45, 745–753(2001).
Stallmach, F. and J. K¨ arger, “The Potentials of Pulsed Field Gradient NMR for Investigation of Porous Media,” Adsorption, 5, 117–133 (1999).
Stallmach, F., J. K¨ arger, C. Krause, M. Jeschke, and U. Oberhagemann, “Evidence of Anisotropic Self-Diffusion of Guest Molecules in Nanoporous Materials of MCM-41 Type,” J. Am. Chem. Soc., 122, 9237–9242(2000).
Tabony, J. and T. Cosgrove, “Diffusion Coefficients of Small Molecules at the Gas-Solid Interface as Measured by the Nuclear Magnetic Resonance Pulsed Field Gradient Method,” Chem. Phys. Lett., 67, 103–106(1979).
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Krause, C., Stallmach, F., Hönicke, D. et al. A Surprising Drop of the Diffusivities of Benzene in a Mesoporous Material of Type MCM-41 at Medium Pore Filling Factors. Adsorption 9, 235–241 (2003). https://doi.org/10.1023/A:1024749800809
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DOI: https://doi.org/10.1023/A:1024749800809