Microkinetic Modeling of Furan Hydrodeoxygenation over Transition-Metal Surfaces

Hydrodeoxygenation (HDO) of biomass-derived oxygenates
present
in bio-oil is a critical step in their conversion to high-value chemicals
and fuels. Furanics represent a significant fraction of the bio-oil
and are considered as potential platform chemicals to yield a variety
of valuable chemicals. In this study, density functional theory calculations
and a descriptor-based microkinetic modeling (MKM) approach were utilized
to investigate furan HDO on transition-metal surfaces and predict
activity and selectivity for the formation of ring-hydrogenated product
like dihydrofuran (DHF), open-chain alcohols, aldehydes, and deoxygenated
molecules as a function of carbon (EC)
and oxygen-binding energies (EO). Deoxygenated
products were favored at high temperatures and low pressures on surfaces
with weak EC and strong EO, while alcohols were favored on surfaces with weak EO and low temperatures. DHF and aldehyde formation
were favored at high H2 pressures and low temperatures
on surfaces having very weak oxygen-binding energies and very high
carbon/oxygen-binding energies, respectively. Ni had high activity
and selectivity toward deoxygenated products in agreement with experimental
observations, while Pd and Pt show the highest activity and selectivity
toward ring-hydrogenated products. Our MKM analysis was extended to
screen single-atom alloy surfaces for HDO activity, and NiFe was found
to be a potential deoxygenating catalyst in agreement with previous
experimental studies.