Title: Graphitic nanocrystals inside the pores of mesoporous silica: Synthesis, characterization and an adsorption study
Authors: de Clippel, Filip ×
Harkiolakis, A
Vosch, T
Ke, X
Giebeler, L
Oswald, S
Houthoofd, Kristof
Jammaer, Jasper
Van Tendeloo, G
Martens, Johan
Jacobs, Pierre
Baron, G. V
Sels, Bert
Denayer, J. F. M #
Issue Date: Oct-2011
Publisher: Elsevier
Series Title: Microporous and Mesoporous Materials vol:144 issue:1-3 pages:120-133
Conference: 16th IZC/7th IMMS Conference Sorrento, ITALY, JUL 04-09, 2010
Abstract: This work presents a new carbon-silica hybrid material, denoted as CSM, with remarkable sorption properties. It consists of intraporous graphitic nanocrystals grown in the pores of mesoporous silica. CSM is obtained by a subtle incipient wetness impregnation of Al-containing mesoporous silica with furfuryl alcohol (FA)/hemelitol solutions. Both the volume match of the impregnation solution with that of the silica template pore volume, and the presence of Al3+ in the silica, are crucial to polymerize FA selectively inside the mesopores. Carbonization of the intraporous polymer was then performed by pyrolysis under He up to 1273 K. The resulting CSMs were examined by SEM, HRTEM, Al-27 MAS NMR, N-2 adsorption. XRD, TGA, TPD, XPS, pycnometry and Raman spectroscopy. Mildly oxidized graphitic-like carbon nanoblocks, consisting of a few graphene-like sheets, were thus identified inside the template mesopores. Random stacking of these carbon crystallites generates microporosity resulting in biporous materials at low carbon content and microporous materials at high carbon loadings. Very narrow pore distributions were obtained when pyrolysis was carried out under slow heating rate, viz. 1 K min(-1). Adsorption and shape selective properties of the carbon filled mesoporous silica were studied by performing pulse chromatography and breakthrough experiments, and by measuring adsorption isotherms of linear and branched alkanes. Whereas the parent mesoporous silica shows unselective adsorption, their CSM analogues preferentially adsorb linear alkanes. The sorption capacity and selectivity can be adjusted by changing the pore size of the template or by varying the synthesis conditions. A relation between the carbon crystallites' size and the shape selective behaviour of the corresponding CSM for instance is demonstrated. Most interestingly, CSM shows separation factors for linear and branched alkanes up to values comparable to those of zeolitic molecular sieves. (C) 2011 Elsevier Inc. All rights reserved.
ISSN: 1387-1811
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Centre for Surface Chemistry and Catalysis
× corresponding author
# (joint) last author

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