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Pyrolysis of Halon 1301 over zeolite catalysts

Li, K., Oghanna, F., Kennedy, E., Dlugogorski, B., Fazeli, A., Thomson, S. and Howe, R. (2000) Pyrolysis of Halon 1301 over zeolite catalysts. Microporous and Mesoporous Materials, 35-36 . pp. 219-226.

Link to Published Version: http://dx.doi.org/10.1016/S1387-1811(99)00222-X
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Abstract

This paper describes the pyrolysis of Halon 1301, CBrF3, in the gas phase and over zeolite catalysts HZSM-5 and NiZSM-5. The gas-phase pyrolysis begins at 973 K and increases with increasing temperature; major products are C2F6 and Br2, although other species such as CF4, CBr2F2 and C4F10 are also detected. Over HZSM-5 catalysts there are high initial conversions to C2F6 and Br2, but the catalyst is quickly deactivated. NiZSM-5 shows high initial selectivity to CF4, but deactivates after ca. 60 min on stream at 973 K, giving C2F6 as the major product of steady state conversion. X-ray diffraction, nuclear magnetic resonance, Fourier transform infrared and X-ray photoelectron spectroscopy measurements show that, although zeolite crystallinity is retained, rapid loss of framework aluminium occurs on exposure to CBrF3 at reaction temperatures, with incorporation of fluorine into the zeolite. Acid sites associated with extraframework aluminium fluoride species are suggested to be responsible for C2F6 formation, and nickel sites in NiZSM-5 for CF4 formation. (C) 2000 Elsevier Science B.V. All rights reserved.

This paper describes the pyrolysis of Halon 1301, CBrF3, in the gas phase and over zeolite catalysts HZSM-5 and NiZSM-5. The gas-phase pyrolysis begins at 973 K and increases with increasing temperature; major products are C2F6 and Br2, although other species such as CF4, CBr2F2 and C4F10 are also detected. Over HZSM-5 catalysts there are high initial conversions to C2F6 and Br2, but the catalyst is quickly deactivated. NiZSM-5 shows high initial selectivity to CF4, but deactivates after ca. 60 min on stream at 973 K, giving C2F6 as the major product of steady state conversion. X-ray diffraction, nuclear magnetic resonance, Fourier transform infrared and X-ray photoelectron spectroscopy measurements show that, although zeolite crystallinity is retained, rapid loss of framework aluminium occurs on exposure to CBrF3 at reaction temperatures, with incorporation of fluorine into the zeolite. Acid sites associated with extraframework aluminium fluoride species are suggested to be responsible for C2F6 formation, and nickel sites in NiZSM-5 for CF4 formation.

Publication Type: Journal Article
Publisher: Elsevier
Copyright: © 2000 Elsevier Science B.V.
URI: http://researchrepository.murdoch.edu.au/id/eprint/28036
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