Microkinetic Modeling and Reduced Rate Expressions of Ethylene Hydrogenation and Ethane Hydrogenolysis on Platinum

Using a hierarchical multiscale methodology, a thermodynamically consistent surface reaction mechanism has been developed to capture the C−C and C−H chemistries of ethylene hydrogenation and ethane hydrogenolysis on platinum. This mechanism, consisting of 32 reversible elementary reactions, describes kinetically limited ethane hydrogenolysis and ethylene hydrogenation experimental data under diverse temperature and composition conditions. Under hydrogenolysis conditions, sensitivity analysis shows that C−C bond cleaving reactions are rate-determining and that most C−C bond cleaving reactions occur through the ethyl and ethylidene surface intermediates. Under hydrogenation conditions, sensitivity analysis shows that both hydrogenation reactions (π-bonded ethylene to ethyl and associative desorption of ethyl to ethane) are rate-controlling. Finally, to enable reactor design and systems simulations, the full mechanism is reduced to two separate, reduced microkinetic models and one-step rate expressions that ...