EAGER: Catalytic Reaction Coupling of Bio-oil Hydrodeoxygenation and Alkane Dehydrogenation

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The development of economically viable techniques for manufacturing liquid transportation fuels from bio-oils produced by pyrolysis of lignocellulosic biomass is a grand challenge with important societal and environmental sustainability implications. One of the obstacles is the high hydrogen requirement for removing the undesired oxygen from the bio-oil via a chemical reaction called catalytic hydrodeoxygenation (HDO). On the other hand, recent developments in shale gas technologies have led to the production of vast amounts of under-utilized light alkanes, which could serve as a source hydrogen for bio-oil HDO. The main objective of this EAGER project is to explore the direct coupling reaction of bio-oil HDO and light (C2-C4) alkane dehydrogenation (DH) using a new family of bifunctional catalysts.The central hypothesis of the proposed exploratory research is that an integrated catalyst design, consisting of a precious metal (e.g., Pt) and an oxophilic metal (e.g., Mo) on a low acidic and weak electronegative metal oxide support (e.g., TiO2), will enable the proposed reaction coupling scheme. Such a catalyst concept is theoretically possible, based on thermodynamic analysis, but has not been experimentally proven and remains untested. If successful, such a catalyst will radically transform the existing bio-oil upgrading and olefin production methods. Three specific research aims will be pursued to explore the feasibility of this concept: (1) the effect of metal site size and metal-metal site distance will be determined; (2) the influence of oxophilicity of the bio-oil HDO sites will be revealed; (3) the impact of support composition will be characterized. To obtain molecular-level understanding of the surface reaction pathways, the bifunctional catalysts will be synthesized with their structures controlled at the nanoscale. Catalyst activity will be measured based on the yields of desired and undesired products from the flow reactor experiments. The dependence of product distribution on (1) the size of the precious metal site, (2) the distance between the DH and HDO sites, (3) metal-oxygen bond strength of the oxophilic metal site, and (4) the compositions of the metal oxide support will be determined. The proposed exploratory research may lead to fundamental understanding of the catalytic geometric and electronic effects on the chemical kinetics of the surface reactions. In addition to training two graduate students, the principal investigators plan to integrate research outcomes into undergraduate and graduate curricula.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.