Abstract
Two areas of concern to man are pollution control and the discovery of renewable resources. The conversion of unutilized biomass to useful chemicals combines both these items. In this sense, we have advocated the Biomass Refinery Social System. The high temperature compressed water decomposition process we developed so far is an important elemental process of the system, which can be operated without any additional catalyst. In order to the implementation of this process, it is necessary to demonstrate the effective continuous decomposition of biomass under high concentration. In this study, we investigated the chemical decomposition of cellulose in newly manufactured continuous high temperature compressed water reactor (25 mm in diameter; 1,500 mm in length) equipped with screw-feeder to allow the feed of high concentration slurry.The decomposition of microcrystalline cellulose was performed to clarify the effects of cellulose concentration, operation temperature, and reaction time, while the operation pressure was set as 15 MPa. It was found from the results that the cellulose was decomposed to valuable chemicals such as furfural, 5-hydroxymethylfurfural (5-HMF), and sugars (mainly glucose) effectively even in high concentration (10wt%). The maximum yields of furfural, 5-HMF, and sugars in this concentration were 0.02, 0.09 and 0.11 gC/gC-cellulose, respectively. The yields were affected by feed concentration, operation temperature and reaction time within the range of 3 to 10 wt%, 240 to 260 degree C, and 7.5 to 20 minutes, respectively. A numerical description of the decomposition mechanism of cellulose in the reactor was also discussed.
