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Modelling the effect of water on cation exchange in zeolite A

Higgins, FM; de Leeuw, NH; Parker, SC; (2002) Modelling the effect of water on cation exchange in zeolite A. J MATER CHEM , 12 (1) 124 - 131.

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Abstract

Classical energy minimisation techniques have been employed to model the effect of hydration on the adsorption behaviour of extra-framework cations Na+, Cs+, Ca2+, Ba2+, Cd2+ and Sr2+ in zeolite A. The experimental structure of zeolite CaNa-A (Si/Al = 1) is reproduced accurately, while the energetically preferred position for water molecules is calculated to be inside the alpha -cage, in agreement with experiment. The preferential locations for the sodium and calcium ions in the hydrated zeolite A are governed by the water molecules and are calculated in the siliceous structure to be the beta -cages (S6R position) for Na+ and beta -cages (S6R' positions) for Ca2+. These locations are in agreement with experimental findings of zeolite A structures, but have not previously been calculated for the calcium position.

Type:Article
Title:Modelling the effect of water on cation exchange in zeolite A
Keywords:COMPUTER-SIMULATION, CRYSTAL-STRUCTURE, CLINOPTILOLITE, DIFFUSION, DYNAMICS, 5A, REFINEMENT, CHABAZITE, DIOXIDE, DEFECT
UCL classification:UCL > School of BEAMS > Faculty of Maths and Physical Sciences > Chemistry

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