Uncovering the Atomistic-Scale Catalytic Roles of Hydrogen Transfer at Liquid-Solid Interfaces for the Targeted Removal of Oxygen from Bio-Oil Compounds
EMSL Project ID
50478
Abstract
A grand challenge for catalysis this century is to accelerate the carbon cycle–wherein fossil fuels derived from biomass formed over 300 million years ago are extracted from the ground and then used to produce energy, fine chemicals, and environmentally damaging greenhouse gases–to the speed of catalytic chemistry. Thermochemical treatment of lignocellulosic biomass produces an array of hydrocarbon compounds that resemble fossil fuel sources and petrochemicals, but suffers from high oxygen content and requires catalytic upgrading in the form of hydrodeoxygenation (HDO) in order to produce sustainable biofuels and bioproducts. Further complicating the design of effective HDO catalysts is the complexity and heterogeneity of the biomass feedstocks, which contain complex functional groups like ketones, acids, aldehydes, and phenolics. To minimize hydrogen consumption and thus upgrading cost, HDO catalysts must be able to effectively transport hydrogen to and from bio-based hydrocarbons at the catalyst surface, resulting in the selective targeting of the C-O bonds. Such transport can be significantly enhanced through solvent effects at the liquid-solid interface, but increases the design variables for the optimum performance of HDO catalysts. Therefore, there is a critical need for fundamental insight into the atomistic-scale elementary HDO reactions occurring at the liquid-solid interface. To enable sustainable access to biofuels and bioproducts, we propose to address the scientific issues related to the atomistic-scale interplay between polar protic solvents and metal nanoparticle surfaces at the liquid-solid interface during elementary hydrogen transport, C-H formation, and C-O cleavage reactions under realistic HDO conditions. We particularly aim to provide an atomistic understanding of the identity and formation of reactive surface hydrogen species under liquid phase HDO conditions and the subsequent elementary reaction steps directly leading to the targeted cleavage of C-O bonds. We expect to identify key predictors in the electronic character of transition metal nanoparticle surfaces which can be used to develop new, cheaper, and higher performing HDO catalysts. Our central hypothesis is that protons formed from the ionization of H adatoms at the interface between transition metals and polar protic solvents will accelerate key hydrogen transfer steps during the HDO of phenolics and that the ionization potential of H adatoms can be used to predict the HDO activity and selectivity of metal catalyst surfaces. We propose to use the critical theoretical capabilities available at EMSL to understand the interactions at the liquid-solid interface that are associated with catalytic conversion of lignocellulosic biomass in the condensed phase. Throughout the course of this project, a close correlation between experiment and theory on model catalysts will be performed in order to reduce both the computational expense and experimental efforts in characterizing such complex systems. To reach this goal, we have assembled a team with a wealth of experience in both the application and science of heterogeneous catalysis and track of record in collaborating with EMSL staff in producing high impact science, especially as related to the catalytic hydrodeoxygenation of phenolic compounds, and with outstanding expertise in the diverse tools necessary to achieve the objectives of the proposed studies.
Project Details
Start Date
2018-10-01
End Date
2019-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Co-Investigator(s)
Team Members
Related Publications
Hensley A., Y. Wang, and J. Mcewen. 2019. "The partial reduction of clean and doped a-Fe2O3(0001) from first principles." Applied Catalysis. A, General 582. PNNL-SA-147349. doi:10.1016/j.apcata.2019.02.019