Recent progress in converting biomass to biofuels and renewable chemicals in sub- or supercritical water

Abstract

This review covers recent research and development undertaken in converting biomass (lignocelluloses, carbohydrates, waste vegetable oil and algae) to biofuels and renewable chemicals using sub- or supercritical water (SCW) as thermochemical reaction media. Applications of SCW technology in pretreating biomass for bioethanol production by fermentation and in hydrogen/methane production by gasification are not covered in this review. The focus is on research progress in understanding the conversion characteristics of model biomass compounds, such as hemicellulose, cellulose, triglycerides and, to a lesser extent, real heterogeneous biomass in SCW. Specific attention is given to promising reaction pathways and novel process development in SCW conversion of biomass and its model compounds. There are good opportunities for the use of biomass feedstocks and SCW technology in the production of liquid fuels for the transportation sector, as well as renewable chemicals for the chemical industry. However, a broad range of fundamental and exploratory research is still needed to advance understanding of the complex conversion chemistry of real biomass in SCW.

Acknowledgements

The authors would like to thank James White, an undergraduate student in our department, for assisting the literature search.

Financial & competing interests disclosure

The authors received funding from the United Soybean Board on a project converting crude glycerol to acrolein using supercritical water technology. The authors have no other relevant affiliations or financial involvement with any organization or entity mentioned in this review with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony or royalties.

No writing assistance was utilized in the production of this manuscript.