Liquefaction of woody biomass by flow through hot-compressed water

Flow-through hot-compressed water apparatus was used to study the performance of liquefaction of Japanese beech. The experiments were operated at pressure of 10 MPa, flow rate of 10 mL/min with various temperature from 160℃ to 280℃. The effect of temperature on saccharides from hemicelluloses, saccharides from cellulose and decomposed compounds in water-soluble portion was studied. Water-soluble portion increased with temperature and 96.5% wood could be hydrolyzed into water at 280℃. Both sacchairdes from hemicelluloses and saccharides from cellulose increased with temperature, which reached maximum value at 250℃ and 280℃, respectively. 5-HMF and furfural increased with temperature as well. Meanwhile, X-ray was carried out to investigate the crystallinity of water-insoluble residues. The crystalline index increased with temperature, however, it decreased suddenly at 280℃ and the peak of (002) lattice plane disappeared, which showed that the crystal structure of cellulose was destroyed completely. Furthermore, the typical hemicelluloses peak was disappeared at 250℃ according to FT-IR spectra, which indicated that hemicelluloses were completely hydrolyzed at 250℃. At 280℃, not only hemicelluloses peak but also cellulose peaks disappeared, while characteristic peaks of water-insoluble residue were lignin-derived aromatic skeleton. It is concluded that flow-through hot-compressed water can be used to completely hydrolyze woody-biomass for saccharides production.