Ketal-rich bio-petroleum from lignocellulosic biomass: a tunable feedstock for green hydrocarbon production under refinery conditions

Abstract

The intensive use of fossil feedstocks has raised numerous concerns regarding their environmental impact. As of 2023, renewable energy including modern biofuels, traditional biomass, and other sources accounted for only 8% of global final energy consumption. Recently, our research group developed a novel methodology to convert second-generation biomass into a liquid product, which is a viscous, brown oil composed primarily of carbohydrate-derived O-isopropylidene ketals (CKs), with mono- and di-isopropylidene derivatives of glucose and xylose, called bio-petroleum (BP). Given the successful proof of concept for the direct conversion of BP into green hydrocarbons within refinery processes, the present study seeks to evaluate the capacity of various lignocellulosic biomasses to yield BP. The results presented in this study demonstrate that various lignocellulosic biomasses can be effectively converted into BP enriched in carbohydrate-derived isopropylidene ketals through hydrolysis–ketalization reactions under mild processing conditions. Up to 50% of the original biomass carbohydrate content was recovered in the form of monosaccharide diisopropylidene ketals in a sequence where hemicellulose is first removed, followed by amorphous cellulose, and finally crystalline cellulose. This progression enables temperature-controlled tailoring of BP composition, offering a means of modulating the performance of BPs in refinery downstream upgrading processes for fuel production.