Simultaneous thermal liquefaction of sugarcane bagasse and esterification with ethanol and fusel oil: One-Step process for biofuel production

Abstract

Sugarcane bagasse is an abundant residue from the ethanol/sugar industries and its liquefaction can be a low-cost process for the production of liquid biofuels. However, the resulting biocrude has high acidity, which requires an upgrading before being used. In this study, ethanol and fusel oil, which is the heavy residue of ethanol distillation made up of higher alcohols, were used as solvents for the liquefaction of bagasse. The 1:10 biomass:solvent ratio mixture was used at 300 °C for 30 min and (10 bar) N2 atmosphere. A mixture of both solvents was also tested to make a comparative study. The process with ethanol showed 72% bagasse conversion, but the best result showed 91% with fusel oil, producing a low biochar content (9%). After the distillation of the liquid product, a biocrude with high combustion heat (30.6 MJ.kg−1) and rich in esters was obtained. The results of GC/MS revealed the greater presence of esters with substituted isoamyl groups (51.2%) and, to a lesser extent, phenolic compounds (2.5%). The biochar has a higher heating value of 30 MJ.kg−1 and special thermal stability, suitable for application as a solid fuel. The biocrude was mixed with marine diesel (5%) and the properties of the mixture were evaluated, without relevant modifications. This innovative process showed the use of two residues, bagasse, and fusel oil, to produce a biofuel to be used with different types of diesel, with economic and environmental gains in a cycle economy for the ethanol industry.