Understanding the Mechanism of Cypress Liquefaction in Hot-Compressed Water through Characterization of Solid Residues

Abstract

Abstract:The mechanism of hydrothermal liquefaction of cypress was investigated by examining the effects of temperature and retention time on the characteristics of the solid residues remaining after liquefaction. The solid residues were divided into acid-soluble and acid-insoluble residues. Results showed the polymerization reactions also mainly occurred at low temperatures. The reactive fragments transformed into acid-insoluble solid residue in the form of carbon and oxygen through polymerization reactions. The process of cellulose degradation consists of two steps: an initial hydrolysis of the more solvent-accessible amorphous region and a later hydrolytic attack on the crystalline portion. Hemicelluloses were decomposed into small compounds during the initial stage of the cypress liquefaction process, and then these compounds may rearrange through polymerization to form acid-insoluble solid residues above 240 °C. The higher heating value of the solid residues obtained from liquefaction at 260-300 °C was 23.4-26.3 MJ/kg, indicating that they were suitable for combustion as a solid fuel.

Understanding low-lipid algae hydrothermal liquefaction characteristics and pathways through hydrothermal liquefaction of algal major components: Crude polysaccharides, crude proteins and their binary mixtures

“…Then different cyclic ketones or phenols are formed through dehydration, isomerization and cyclization. Previous reports found that carbohydrates tend to form aromatics (Liu et al, 2013), which is consistent with our findings. The relatively high contents of ions in subcritical aqueous solution Bio-oils from polysaccharides-proteins mixture obtained at 260 o C and 300 o C were analyzed by GC-MS (Table 3 and 4).…”

“…The bands at 1600 and 1400 cm -1 are attributed to aromatic skeleton vibrations. Results indicated that residue contained a certain amount of organic substances, consistent with the results of previous literature (Liu et al, 2013).…”

“…The overall lower bio-oil yield might due to large amounts of molecules in polysaccharides breaking down to polar water-soluble organics and not to non-polar hydrocarbon type structures. Therefore, the contribution to bio-oil from polysaccharides is small.For crude proteins liquefaction, bio-oil yield increased from 7.43% at 220 o C to16.29% at 280 o C and slightly decreased at 300 o C, while residue yield decreased from 15.95% at 220 o C to 5.44% at 300 o C with the increasing temperature. This has an opposite trend with the polysaccharides liquefaction.…”

Rapid liquefaction of giant miscanthus feedstock in ethanol–water system for production of biofuels

“…The increase in the bio-oil yield with temperature can be attributed to the higher solvolysis effect of biomass components at relatively higher temperatures. Through solvolysis, biomass components (cellulose, hemicellulose, and lignin) are broken to their monomers, and these monomers are converted to liquid and gaseous compounds [21][22][23]. About 50% biooil yield was obtained at 280°C and 50% water/ethanol ratio.…”

Physicochemical modifications of dietary palm kernel meal affect growth and feed utilization of Nile tilapia (Oreochromis niloticus)

“…The spectral bands at 1078, 1416 and 1657 cm −1 represent the presence of lignin as indicated by ␤(1-3) polysaccharide (Szeghalmi et al, 2007), benzene ring stretching vibrations (Liu et al, 2013) and C O in conjugated carbonyl groups (Yang et al, 2010), respectively. The 1461 and 1548 cm −1 bands are related to the skeleton stretching vibration of the aromatic rings and C H deformation in lignin (Fu et al, 2012).…”