Experimental and Atomistic Simulation Study of the Structural and Adsorption Properties of Faujasite Zeolite-Templated Nanostructured Carbon Materials

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• 作者：Thomas Roussel ; Antoine Didion ; Roland J.-M. Pellenq ; Roger Gadiou ; Christophe Bichara ; Cathie Vix-Guterl
• 刊名：Journal of Physical Chemistry C
• 出版年：2007
• 出版时间：November 1, 2007
• 年：2007
• 卷：111
• 期：43
• 页码：15863 - 15876
• 全文大小：1639K
• 年卷期：v.111,no.43(November 1, 2007)
• ISSN：1932-7455

文摘

Nanostructured carbon materials were obtained by templating faujasite zeolites. This was achieved by liquidinfiltration of furfuryl alcool and chemical vapor deposition of propylene and acetonitrile. These carbon materialswere characterized by adsorption of gaseous nitrogen and carbon dioxide, and the carbon structure wasinvestigated by X-ray diffraction (XRD). They exhibit a very large pore volume in the micropore region (i.e.,narrower than 2 nm), and the XRD spectra show the presence of a nanostructured carbon material with awell-defined unit cell whose size and symmetry are imposed by the zeolite template. We made use of GrandCanonical Monte Carlo simulation of carbon adsorption in order to obtain numerical models of such materialsand study their texture and mechanical and adsorption properties on an atomistic scale. The carbon-carboninteractions were modeled within the frame of the tight binding and the reactive bond order (REBO) formalisms,while carbon-zeolite interactions were assumed to be relevant to physisorption and described with the PN-trAZ potential. This simulation strategy allowed us to obtain numerical replica that are well-ordered and theopposite of the original 3D zeolite porosity. The numerical samples obtained at various temperatures aremade of curved surfaces containing almost exclusively sp² carbon atoms and are very rigid and stiff. Thecalculated structure factor of such a numerical sample exhibits features that are present in the experimentaldiffractograms, hence validating the nanocasting procedure. However, the comparison between simulatednitrogen adsorption isotherms at 77 K with experimental values lead us to understand that the real materialis defective and contains cavities of a few nanometers in size, larger that those of the perfect original numericalsamples. Finally, we found from both experiment and simulation that pure carbon replicas of faujasite zeolitethat have optimized pore dimensions are not good candidates for hydrogen storage at room temperature andmoderate pressures, allowing us to draw general conclusions on the use of porous carbon for such an application.