Adsorption of chlorofluorocarbons in nanoporous solids; a combined powder neutron diffraction and computational study of CFCl3 in NaY zeolite

Caroline Mellot-Draznieks; Juan Rodriguez-Carvajal; Dave E. Cox; Anthony K. Cheetham

doi:10.1039/B212330B

Adsorption of chlorofluorocarbons in nanoporous solids; a combined powder neutron diffraction and computational study of CFCl₃ in NaY zeolite†

Caroline Mellot-Draznieks,*^a Juan Rodriguez-Carvajal,^b Dave E. Cox^c and Anthony K. Cheetham^d

* Corresponding authors

^a Institut Lavoisier, Université de Versailles Saint-Quentin, 45 avenue des Etats-Unis, 78035 Versailles Cedex, France
E-mail: mellot@chimie.uvsq.fr
Fax: +44 1 39 25 43 58
Tel: +44 1 39 25 43 77

^b Laboratoire Léon Brillouin, CEA/Saclay, 91191 Gif sur Yvette, France

^c Brookhaven National Laboratory, Upton, New York, USA

^d Materials Research Laboratory, University of California Santa Barbara, CA, USA

Abstract

The crystal structure of NaY (Na₅₄Si₁₃₈Al₅₄O₃₈₄) + CFCl₃ has been determined at 20 K by Rietveld analysis of powder neutron diffraction data in space group Fd [3 with combining macron] m. The sodium cations were located preferentially in sites II, which are fully-occupied and also in sites I, which are half-occupied. A new cation position in the β-cages was detected around x = 0.125, y = 0.125, z = 0.031. Important cation migration is observed upon adsorption of CFCl₃, as shown by the absence of cations in sites I′, known to be a favorable cation site in bare NaY, together with the detection of this new site in the β-cages. Part of extraframework cations remained undetected, that were assumed to be located in the supercages in low symmetry sites. The CFCl₃ molecules are found in the 12-ring windows, where they accomodate Cl⋯O_zeolite and F⋯O_zeolite van der Waals interactions together with Cl⋯Na(II) electrostatic interactions. (N,V,T) Monte Carlo simulations were performed in order to elucidate the role of extraframework cations in the adsorption of CFCl₃ in NaY. They show that the presence of Na ions in the 12-ring window (sites III′) has to be taken into account in order to get adsorption geometries consistent with that obtained from neutron diffraction.

This article is part of the themed collection: In celebration of Tony Cheetham’s 70th birthday

Article information

https://doi.org/10.1039/B212330B

Article type

Paper

Submitted

12 Dec 2002

Accepted

17 Mar 2003

First published

28 Mar 2003

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Phys. Chem. Chem. Phys., 2003,5, 1882-1887

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Adsorption of chlorofluorocarbons in nanoporous solids; a combined powder neutron diffraction and computational study of CFCl₃ in NaY zeolite

C. Mellot-Draznieks, J. Rodriguez-Carvajal, D. E. Cox and A. K. Cheetham, Phys. Chem. Chem. Phys., 2003, 5, 1882 DOI: 10.1039/B212330B

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