PNNL

Abstract

This work examines a solvent extraction process for Hydrothermal Liquefaction (HTL) biocrude utilizing naphtha range hydrocarbons. A process for low pressure, low temperature, two-stage solvent extraction and separation for HTL products is described. A series of lab scale experiments were carried out to demonstrate the basic process and evaluate key parameters. We examined the solubility dynamics of biocrude in different solvents and observed similar qualitative behavior to bitumen when it comes to paraffin versus naphthene or aromatic solvent composition. Specifically, the biocrude displayed near complete solubility in toluene at elevated temperatures, partial solubility in decane, and intermediate solubility in methyl cyclohexane. The laboratory work indicates that aliphatic/aromatic solvent mixtures at 80°C result in recovery of nearly 100% of the biocrude from the product mixture with reduced carbon content on the HTL solids. The findings illuminate the potential of solvent extraction for HTL biocrude processing.