Upgrading of biomass-derived solar hydrothermal bio-oils through catalytic hydrodeoxygenation in supercritical ethanol

Abstract

The use of concentrated solar energy as the heat source to perform hydrothermal liquefaction (HTL) of biomass is a promising alternative to improve the thermal efficiency of the process and reduce the environmental impact of the use of fossil fuels. However, the HTL of lignocellulosic biomass produces a bio-oil that still requires an upgrading treatment to improve its properties as fuel. In the present work, bio-oils obtained from solar hydrothermal liquefaction of Agave and corncob were upgraded for the first time by hydrodeoxygenation (HDO) in supercritical ethanol using a Mo2C catalyst supported in carbon nanofibers. The main results showed yields up to 69% of the upgraded bio-oil and a deoxygenation grade of 71%, with HHV values around 35 MJ/kg for most of the upgraded bio-oils. Moreover, it was observed that HDO treatment of the solar bio-oils can produce upgraded bio-oils with chemical properties and yields similar to those produced by conventional thermochemical methods, which opens the door to extend the use of concentrated solar technologies for the whole process: from biomass thermochemical conversion to its upgrading into drop-in fuels.