Lignin has high carbon content and is potentially the largest renewable resource of aromatic chemicals and fuels. We describe in this study the use of Nb2O5 catalyst in two different ways to convert lignin monomers into C9 hydrocarbons and tri-epoxide polymer precursors. The Nb2O5 prepared at a low temperature (450 °C) was shown to contain acid sites that enhance the conversion of lignin monomers. On one hand, a physical mixture of Ru/C and Nb2O5 was found to be an effective catalyst for funneling multiple lignin monomers under low H2 pressure at 250 °C to a clean cut of hydrocarbon liquid fuels.1 The reaction solvent is water with a small amount of methanol additive as the secondary hydrogen source. Under optimized conditions, 100% conversion of lignin monomers mixture of dihydroeugenol (DHE), isoeugenol, and 4-allylsyringol were achieved to fully deoxygenated products. Propyl cyclohexane (76%) and propyl benzene (24%) were observed as the C9 hydrocarbons. On the other hand, Nb2O5 itself was found to be active for converting the lignin monomer, 4-propyl-2,6-dimethoxyphenol (DMPP), to a unique tri-functional compound propylpyrogallol (DMPPO). DMPP is selectively made from gene-modified high-S lignin biomass. At 230 °C, DMPP was converted almost quantitatively (96% yield) to DMPPO over Nb2O5 in water medium. Notably, DMPP made from the biomass contained impurities, but these impurities did not negatively impact the catalyst, which the Nb2O5 can be recycled twice without any notable deactivation. As a result, our study demonstrates a simple and green strategy for utilizing biomass monomers as a feedstock to make renewable hydrocarbon fuels and polymer building blocks via Nb2O5 catalyzed reactions.

Utilization of lignin monomers catalyzed by Nb2O5 to C9 hydrocarbons and biobased tri-epoxides

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.