Al and Ni K-edge XANES and EXAFS experiments have been undertaken to characterise the chemical states of aluminium and nickel in NiZSM-5 catalysts used for the pyrolysis and hydrodehalogenation with methane of Halon 1301 (CF3Br). It is shown that pyrolysis of Halon 1301 over NiZSM-5 involves both extra-framework aluminium fluoride or hydroxyfluoride species and aggregated nickel species, probably fluorided. Reaction products are CF4 and C2F6. The reaction between Halon 1301 and methane over NiZSM-5 produces CHF3 and CH3Br as major, but not exclusive products. In the presence of CH4 framework dealumination and aggregation of nickel is inhibited. Future prospects for utilising these and similar catalysts in reactions of other Halons and CFCs to produce useful fluorocarbon products as an alternative to destruction are briefly discussed. (C) 2002 Elsevier Science B.V. All rights reserved.
- supported palladium catalysts
- CCL2F2 CFC-12