The reactions of perfluoroisobutene on metal-impregnated charcoal

The reactions of perfluoroisobutene (PFIB) on the surface of metal-impregnated and nonimpregnated charcoals have been studied. X-ray photoelectron spectroscopy has been used to determine changes on the charcoal surface after reaction. Free fluoride was shown to be left on the charcoal surface, along with an adsorbed fluorocarbon species which is not PFIB. Thermal desorption spectroscopy was carried out by monitoring the reactions by mass spectrometry during heating of the sample. Factor analysis was then used to deconvolute the mass spectra. For the non-impregnated charcoal, some conversion of PFIB to higher-mass fluorocarbon fragments was observed, but there is little evidence for hydrolysis or conversion to TTFM (tris (trifluoromethyl) methane). However, for the charcoal impregnated with copper and chromium, some conversion of PFIB to TTFM was shown to occur. (C) 1997 Elsevier Science Ltd.