Concluding remarks on the theory of selective energy transfer and exemplification on a zeolite kinetics study

Abstract

Some 30 years ago it was suggested that catalytic reactions that showed a 'compensation' effect were activated through a vibrational resonance between that one vibrational mode of the reactant that led to reaction and a comparable vibration mode of the catalyst system that represented the energy input. The isokinetic effect can be calculated from this model, in some cases within less than 1 % from the experimental values. The application of the selective energy transfer model to various kinetic investigations provides some rules: (1) The resonance interaction can occur between the quantum of the catalyst vibration and the quantum of the reactant vibration in a ratio of small integers. (2) The activation energy is built up by a certain number of vibrational quanta relating to the critical vibration. (3) The isokinetic temperature can be expressed as a function of the wavenumber of the catalyst vibrator and the wavenumber of the reactant vibrator. (4) The isokinetic data can be used to establish reaction mechanisms. (5) One can also extract the anharmonicity constant of the critical vibration from the data. One observation is that the reacting molecule is not markedly adsorbed, whereas, of course, the remaining molecules may be strongly adsorbed. (Less)