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 (E_C) and oxygen-binding energies (E_O). Deoxygenated products were favored at high temperatures and low pressures on surfaces with weak E_C and strong E_O, while alcohols were favored on surfaces with weak E_O 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.