Kinetic modeling of THF co-solvent enhanced production of furfural, HMF, and levulinic acid

Petroleum is the primary feedstock for liquid fuels production and also provides a platform for synthesis of valuable chemicals and polymers. The historically high price of petroleum products and concern about the impact of fossil emissions of carbon dioxide on global climate change make it important to develop sustainable routes for production of fuels and chemicals. Furfural, 5-hydroxymethylfurfural (HMF), and levulinic acid (LA) are important fuel precursors (FP) that can be derived from lignocellulosic biomass and converted into drop-in fuels compatible with the existing fuel infrastructure. We recently developed a novel co-solvent system we call Co-solvent Enhanced Lignocellulosic Fractionation (CELF) that employs low boiling tetrahydrofuran (THF) in solution with water to improve yields of FPs from lignocellulosic biomass.  This novel system achieves >87% yields of furfural, removes more than 90% of original lignin, and produces a highly reactive glucan rich solids residue. In this study, we developed kinetic data for THF co-solvent assisted fuel precursor production from pure sugars and biomass. First, the effect of various operating conditions on carbohydrate breakdown and FP yields were determined. Then, kinetic models were developed from that data to help define reaction conditions that favored the highest yields of each fuel precursor for the THF co-solvent system. In order to understand how CELF improves fuel precursor yields, we identified which kinetic parameters were impacted by the presence of THF and how addition of different metal halide catalysts further changed their values.