THERMAL-DESORPTION OF N-ALCOHOLS INTERCALATED IN VANADIUM PENTAOXIDE HYDRATE

The mechanism of irreversible adsorption and thermal desorption of n-a lcohols, having carbon numbers m = 1-7, have been studied on V2O5.nH2O by the use of thermal gravimetry, mass spectrometry, X-ray diffractio n and Fourier-transform infrared spectroscopy. All the alcohols studie d are dissociatively adsorbed as alkoxide by attacking the V-O bonds o f the intralayer structure. Thermal desorption of alcohol occurs by on e of, or a combination of, three processes (1) molecular desorption, ( 2) evolution of chemical species produced by catalytic reaction with t he substrate such as methanal (methanol), ethene (ethanol), propene (p ropan-1-ol) etc., (3) decomposition by combustion with oxygen of the l ayer structure to produce CO2, CO and H2O, which are desorbed, and dec omposition products such as polymerized species and/or carbides, which are deposited in the solid. The formation of the latter compounds del ays the structural changes of the solid to form oxides of vanadium ion s of lower valency (e.g. V4+ and V3+).