Abstract
In this study, we report results of experiments of microcrystalline cellulose decomposition using a continuous flow-type micro-reactor in near- and supercritical water.1),2) For understanding a reaction feature of the cellulose, we analyzed solid residues and aqueous products recovered by this treatment. As a result, we could propose a reaction mechanism of cellulose as follows. At the initial stage of reaction, microcrystalline cellulose can swell and dissolve into near- and supercritical water by cleavage of intermolecular hydrogen bond linkages to form activated cellulose, followed in random hydrolysis β(1,4)-glycosidic bond linkages of the cellulose to form water-soluble cellooligomers and glucose. Whereas, pyrolytic depolymerization of the β(1,4)-glycosidic bond linkages of cellulose in the crystalline region.3) From the evaluation of the effects of experimental parameters (temperature, pressure, and residence time) on the reaction, we found it possible to control contribution of each reaction paths to the overall conversion rate of cellulose by manipulating temperature and pressure in near- and supercritical water. Further, based on the above reaction mechanism, we explored optimum conditions where some valuable chemical intermediates formed in a rapid and selective manner at identical conditions.
