Session: Undergraduate Research Posters: Computational Chemistry:

Biomass is recognized as a sustainable resource to offset fossil fuel demand and reduce greenhouse gas emissions. Biomass can be broken down into bio-oil compounds through pyrolysis and hydrothermal liquefaction. To convert the bio-oil into valuable fuels or chemicals, catalytic hydrogenation and deoxygenation are necessary. Electrocatalytic hydrogenation (ECH) can renewably supply the hydrogen equivalents required for hydrogenation via proton reduction in aqueous phase, opening an attractive route to produce high-energy density transportation fuels in a sustainable manner. By understanding and increasing ECH activity and selectivity, the economics for bio-oil conversion can be greatly improved. In this project, the thermodynamics and kinetics of aqueous-phase ECH of phenol to cyclohexanol on platinum and rhodium metals are investigated via density functional theory (DFT) calculations, first-principles microkinetic simulations, and experimental kinetics measurements. The experimentally measured intrinsic rate for ECH of phenol on Pt/C and Rh/C nanoparticles decreases as the average particle size decreases, as well as the fraction of (111) terraces. Therefore, we hypothesize that the active site for phenol hydrogenation is the (111) terrace, which is more prevalent than step sites on the surfaces of larger particles. To test this hypothesis, we performed DFT calculations and microkinetic simulation of phenol hydrogenation on the (111) terraces, (100) terraces, and (553) steps of Pt and Rh. Our microkinetic model predicts the terrace sites are more active than step sites, consistent with experiment. These findings provide atomistic insight into the activity differences between steps and terraces, as well as the impact of hydrogen coverage on phenol ECH.

Oliver Gutierrez

Appearances