Selective production of bicyclic alkanes as high-density fuel additives by coupling lignocellulose-derived furanics and phenolics

Abstract

High-density fuel additives are important for heavy transportation. Production of high-density fuel additives from renewable resources has been receiving increasing attention in recent years. Despite the progress in the depolymerization of lignin, cellulose, and hemicelluloses, there are limited studies on integrating lignin and carbohydrates to make value-added products. Here we design a route to synthesize high-density fuel additives with lignin-derived monophenolics and carbohydrate-derived furanics. We performed Brønsted base-catalyzed C–C coupling of phenolics and furanics followed by hydrodeoxygenation catalyzed by a synthesized Ir–ReO_x/SiO₂ catalyst. Under optimized reaction conditions, the coupling product of phenolics and furanics, bicyclic furyl phenyl precursors, reached a yield of over 90%, and was further hydrodeoxygenated to bicyclohexyl alkanes with a yield of over 98%. The current two-step strategy demonstrates high-selectivity of preparing high-density hydrocarbon fuels from lignocelluloses and provides a possible way to utilize all components of lignocellulosic biomass in an integrated upgrading pathway.