Kinetic Modeling of Pt Catalyzed and Computation-Driven Catalyst Discovery for Ethylene Glycol Decomposition

Knowledge of the underlying mechanisms controlling oxygenate catalytic decomposition to synthesis gas can lead to the design of better catalysts and reactors, enabling the utilization of biomass feedstock for fuels and chemicals. This work studies the decomposition of ethylene glycol, as a simple surrogate to biomass-derived polyols, through the analysis of two catalytic kinetic models. First, a density functional theory (DFT) and statistical mechanical parametrized model of 81 reversible, elementary-like reactions is used to predict and understand ethylene glycol decomposition on Pt. Reaction path analysis indicates that while the majority of decomposition occurs through initial O–H bond breaking, initial C–H bond breaking is active at temperatures around 500 K. Further, sensitivity analysis shows that early dehydrogenation reactions (specifically HOCH 2 CH 2 O* → HOCH 2 CHO* + H*) are kinetically important reactions, rather than C–C bond breaking. We show that steady state reactor conditions open up new reaction pathways not seen in surface science (temperature programmed desorption) experiments. The second model, parametrized based on semiempirical linear scaling and linear free energy relationships, consists of 250 reversible, elementary-like reactions and maps the dependence of ethylene glycol decomposition rate and selectivity to various products versus atomic binding energy descriptors. The results show that an optimal catalyst that maximizes the H 2 production rate should have binding energies of 58, 116, and 145 kcal/mol for atomic hydrogen, oxygen, and carbon, respectively. These models can be used to guide future experimental efforts in developing catalysts for polyol reforming.