New materials from solid residues for investigation the mechanism of biomass hydrothermal liquefaction

Advanced analysis technologies cannot be applicable to structural characterization of solid residue from biomass hydrothermal liquefaction due to its insoluble characteristics in organic solution. In this investigation, the milled solid residue fractions were isolated from the solid residues producing during cypress hydrothermal liquefaction at 220, 260, and 300 degrees C. Their fractions structural characteristics were comparatively investigated by advanced analysis technologies such as liquid state Nuclear Magnetic Resonance. Dichloroethane/ethanol insoluble fractions were firstly found during the liquefaction process at 260-300 degrees C and results showed that the fractions were the intermediate component of biomass carbonization and mainly produced from the re-polymerization reactions of lignin during hydrothermal liquefaction process. The presence of crosslinking reactions between carbon carbon which lead to the formation of a highly crosslinked structure resulting in the formation of milled solid residue fractions, which made the fractions be not insoluble in dichloroethane/ethanol and have high thermal stable and molecular weight. Ether structures scission, de-methylation reactions, re-polymerization between carbon-carbon, and fragmentation of large molecular fractions have been occurred in lignin during hydro thermal liquefaction process. The result showed that characterization of milled solid residue fractions provided some new information of the mechanisms of biomass hydrothermal liquefaction.