Interaction of hydrocarbons containing four hydrogen atoms with condensed phases: Classification of H/D exchange mechanisms and mechanism selection algorithm

The paper focuses on an analysis of the mechanisms of hydrogen interaction between gases containing 4 hydrogen atoms and a condensed phase in terms of H/D exchange. Based on the theory of five types of exchange, different cases of mechanisms are analysed according to the accepted values of probabilities of hydrogen isotope exchange between the gas and condensed phases. The analyses made it possible to classify the mechanisms into 3 groups: one-step, two-step, and multistep. Two-step and multistep groups contain two subgroups each. The paper shows that all groups of mechanisms are distinguishable experimentally. An algorithm for selecting the exchange mechanism is proposed. The implementation of the proposed algorithm is shown on a number of experimental data known in the literature. Hydrogen exchange mechanisms have been revised for the following systems: CH₄-H₂SO₄, CH₄-H₂-Ni and CH₄-H₂-Pt-Rh.