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Dynamic behavior of surface complexes of 2-propanol on aluminia during adsorption and dehydration was studied using IR spectroscopy. Good agreement was found between the first-order rate constants of alkene formation in pulse-flow experiments and that of disapearance of a reactive surface complex. It was shown that the simple surface alkoxide 2-Pr-O-Al remains on the surface constant temperature, but it can be completely removed by hydrolysis, or by heating up to 200 °C. The surface carboxylates are formed very slowly and are stable even in the presence of water vapour at 300 °C.

The dynamic behaviour of systems consisting of 2-propanol or tert-butanol and of a solid dehydration catalyst has been studied by means of pulses of the alcohols, water, nitrogen or carbon dioxide, respectively, introduced onto fresh catalyst surface in a stream of nitrogen, or onto the working surface. The catalysts employed were alumina, alumina modified by fluoride, sulphate or sodium ions, respectively, thoria, silica-alumina, phosphotungstic acid and a sulphonated styrene-divinylbenzene copolymer. The positions and shapes of the response curves allowed to distinguish between catalysts operating by formation of surface alkoxides or of protonated alcohols as surface intermediates in the transformation of the alcohols into alkenes.

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