Resource Upgrading in Advanced Supercritical Fluid (Supercritical Fluid with Catalyst and Cosolvent): Liquid Fuels from Biomass in Sub and Supercritical Water and Carbohydrate Up-Conversion in Ionic Liquid and Supercritical Fluids Mixtures

Liquid fuels from biomass and up-conversion of biomass in advanced supercritical fluid are reviewed in this chapter. Lignin can be converted into heavy hydrocarbons in subcritical water extraction. Lipid, which is triglyceride, is catalytically converted into straight-chain hydrocarbons of free fatty acid (decarboxylation) formed by hydrolysis. Carbohydrate is also hydrothermally converted into furan ring compound and fatty acids. Protein is converted into amino acids in hydrothermal water and depolymerization of protein is favored with rapid heating and denaturation agency such as alkaline earth metals. Free amino acids are further decomposed into carboxylic acid through deamination and into amine through decarboxylation. To inhibit Maillard reactions, which result in polymerization, the deamination of amino acid at low temperature was favored and a solid catalyst was quite active for deamination of free amino acids at quite low temperature hydrothermal water. Cellulose was dissolved in some ionic liquids with high mass percentages (5–20 wt%) and converted into monomers and useful components such as furan ring compounds and supercritical fluid cosolvent such as hydrothermal water in ionic liquids supported improvement of reaction efficiency. For hydrogenation of biomass, it was confirmed that hydrogen solubility was enhanced with supercritical carbon dioxide and it must be helpful for hydrogen reaction with biomass molecule

Hydrothermal Extraction of Antioxidant Compounds from Green Coffee Beans and Decomposition Kinetics of 3‑<i>o</i>‑Caffeoylquinic Acid

Separation of antioxidant compounds (caffeoylquinic acids (CQAs), phenolics, melanoidin, and caffeine) from green coffee beans with hydrothermal extraction and decomposition kinetics of 3-<i>o</i>-caffeoylquinic acid (3-CQA) are reported. Antioxidant capacity (AOC) of the extracts increased as extraction temperature was increased up to 410 K and then it decreased up to extraction temperatures of 500 K. As extraction temperature was further increased above 500 K, AOC remarkably increased. The decomposition rate of 3-CQA in water was determined from 433 to 513 K. The increase and decrease in AOC with extraction temperature can be attributed to the hydrolysis of oligomeric structures (glycosides) in the coffee beans that yield CQAs, the decomposition of the CQAs, and to the formation of melanoidins that had a characteristic brown color. Hydrothermal extraction provides an effective method for the separation of antioxidant compounds from green coffee beans, and the effluent extracts may be suitable for food products