Biocrude production from sugarcane bagasse and ethanol over green catalysts based on shellfish waste

Abstract

The development of sustainable fuels has been a great challenge during the last decades. In this regard, this research discusses the liquefaction of sugarcane bagasse, a waste from bio-ethanol and/or sugar manufacture, using water, hydrous ethanol and anhydrous ethanol over shellfish waste catalysts (mussel and crab) constituted mainly by CaCO3. In the absence of catalysts, the bagasse dissolved better in hydrous ethanol (82%) than to dry ethanol (72%) and water (73%). The total yield of biocrude for the process with water was low (18%) because it was necessary to perform a liquid-liquid extraction with an organic solvent to recover it. The yield of the biocrude increased to approximately 60% when ethanol was used instead of water. Reactions with the waste catalysts presented a reduction of biochar content and yielded products with different compositions, mainly due to esterification/hydrolysis reactions between the ethanol, water, and the acids from the biocrude. The biochars and biocrudes presented high-energy content, with a higher heating value between 19.8 and 26.9 MJ.kg−1. The catalysts based on crab residues showed to be a little more effective for liquefaction compared to the catalyst from mussel wastes, due to the presence of more alkaline phases than CaCO3. The biocrude obtained with hydrous ethanol and crab catalyst presented esters (39%), alcohols (6%), and phenols/aromatics (35%). For the reactions with mussel catalyst, the biocrude composition changed to esters (56%), alcohol (5%), and phenols/aromatics (38%). Both biocrudes have the potential to be used as sustainable biofuels for a sugarcane plantation, processing, and other activities. Due to the alkaline compounds present in the solid product, which is a biochar-CaCO3 composite, it could also be used in the soil to neutralize its acidity and reducing cane plantation costs, in a circular economy.