Saccharification of Cellulose Using a Hot-Compressed Water-Flow Reactor

Abstract

Cellulose was hydrolyzed with hot-compressed water (HCW; ∼310 °C, 9.8 MPa) using an HCW-flow reactor. HCW was continuously delivered into a reactor charged with cellulose. The effluent from the reactor was cooled and separated into a water-soluble fraction (WS) and a water-insoluble fraction which deposited after cooling (DP). Cellulose started to decompose into WS and DP when HCW was delivered above 230 °C. The main components of the WS were hexose and oligosaccharides ranging from a dimer to a pentamer, and the DP consisted of polysaccharides ranging from a hexamer to an eicosamer or more polymerized saccharides. When HCW was delivered at 295 °C, nearly all of the cellulose decomposed after a 12-min flow of HCW, and 81 wt % of WS and 18 wt % of DP were obtained. The formation rates of WS and DP increased as the temperature of HCW increased. However, the composition of WS and DP barely changed with the HCW temperature under around 280 °C, which corresponds to the softening point of the cellulose. When the HCW temperature was further increased, the depolymerization of the products proceeded. The decomposition rate of cellulose itself was not affected by the flow rate of HCW, but the depolymerization of the products was suppressed when the flow rate of the HCW was increased.

Cracking of Cellulose over Supported Metal Catalysts

“…At 320 o C and 22 MPa, cellulose is subjected to the water for a short period of time to form glucose and many other products [13,14]. Once again, lack of selectivity for any product and requirement of high energy input restrict its use.…”

Hydrothermal conversion of biomass

“…Primary and small secondary/tertiary decomposition products of glucose conversion in hot compressed water were identified by a number of researchers. 22,23,39,43,46,47,53,[58][59][60][61][62][63][64][65][66] In the capillaries, gas yields and compositions of these components were determined. Formation of WSIS was observed by visual inspection and is, thus, only indicative.…”

Two-Step Hot-Compressed Water Treatment of Douglas Fir for Efficient Total Sugar Recovery by Enzymatic Hydrolysis

“…1a. For cellulose decomposition at temperatures exceeding 230 °C (Sakaki et al 2002), HCW treatments were performed at relatively short residence times (5 min). In addition, eucalyptus, which is highly susceptible to HCW treatment (Yu et al 2010b;Silva-Fernandes et al 2015), was also treated under the same conditions to compare the difference in sugar recovery between softwoods and hardwoods.…”