Proceedings of International Symposium on EcoTopia Science 2007, ISETS07 (2007) Corresponding author: M. Sasaki, msasaki@kumamoto-u.ac.jp Reaction Behavior and Kinetics of Cellulosic Materials in Sub-critical Water Takashi Saito 1 , Hiroaki Kawanabe 2 , Yuki Yoshino 2 Mitsuru Sasaki 2 and Motonobu Goto 1 1. Department of Pulsed Power Science, Kumamoto University, Kumamoto, Japan 2. Department of Applied Chemistry and Biochemistry, Kumamoto University, Kumamoto, Japan Abstract: Recently, biomass resources have been attracted for recovering valuable chemicals. Especially, cellulose is mostly contained in biomass resources. Glucose is the constituent sugar of cellulose, can pro- duce ethanol by fermentation. For these reasons, we focus biomass and its derivation reagents as potential chemical for fossil fuels. One of the method to transform from biomass into some chemicals, in general techniques, for example, one of the representative decomposition methods is a dilution sulfuric acid methods is a dilution sulfuric acid method. The dilution sulfuric acid method with 0.1-2.0% of acid con- centrations and 130~240 o C of reaction temperatures, leads to recover useful chemicals as decomposition products. Although it is very easy to obtain some degraded products, however by-products from secon- dary reactions of the materials have not been studied yet very well. For the purpose of understanding on the reaction behavior of various monosaccharides in the region of high-temperature and high-pressure of water, we investigated reaction pathway and kinetics through reaction experiments of saccharides degra- dation in sub-critical water. The experiment was conducted by using a continuous flow-type micro-reactor. 1.5-10 wt% D(+)-glucose was used as the starting material. The reaction pressure was adjusted from 15-20 MPa. The reaction temperature was adjusted from 200~240 o C. In the case of 240 o C, 20 MPa, 3 wt%, the conversion of D(+)-glucose increased with residence time. And it became 83.1 % at 120 sec. High yield of 2-furfural was obtained at longer residence time. This result indicates that the dehydration reaction was occurred on D(+)-glucose. High concentration of D-fructose, that is an isomer of D-glucose, was observed at the short residence time. This reaction is supposed to be caused by keto-enol tautomeri- zation. 5-HMF was formed in high yield at the longer residence time. This result expresses that the dehy- dration reaction occurred with D-fructose. For the yield of organic acids, almost all products were ob- tained in high yield at the longer residence time. In another series of experiments, some cellulose deriva- tives were used as starting materials to understand their hydrolysis rates in sub-critical water. Keywords: Cellulose, Glucose, Saccharide, Sugar, Sub-critical, Hydrothermal 1. INTRODUCTION In recent years, the energy is increasing in all over the world. The growth in consumption of energy in 2001 is three times as high as its 1965 [1,2]. Fossil fuel is used for the automobiles and the industrials, and it causes the elevation in carbon dioxide concentration in the atmos- phere. From these facts, the biomass is receiving attention for its capability as an alternative to fossil fuels as an chemical resources. Cellulose, hemi-cellulose and lignin are main components of biomass. Especially cellulose, which is contained as a constituent element of biomass. It is also able to convert into energy in diverse ways. In conventional techniques, for example, a dilute sulfuric acid method [3] is representative as one of reaction methods. The dilute sulfuric acid method with 0.1~2.0 % of acid concentrations and 130~240 o C of reaction tem- peratures, leads to recover useful chemicals as decompo- sition products. Although these decomposition methods use sulfuric acid or hydrochloric acid as catalysts, it makes treatment process cumbersome and complicated by the treatment of the harmful catalyst which remains after the process. Therefore, in the conversion of the biomass to the utilization science material, the low-loaded material is selected for environment and de- velopment of the new synthetic method of the environ- ment fitter type and high economic efficiency is desired. Consequently we focus on water as the solvent that is low load to the human body, and advance the research of the conversion method of the biomass under the non-catalytic condition. Because sub-critical and supercritical water have many interesting properties [4], it is widely used as the solvent of extraction and crystallization. In the previ- ous works, a lot of study results that decomposition of saccharide with sub-critical and supercritical water are reported [5-9]. In this study, we carried out the experi- ments of conversion of D(+)-glucose under sub-critical water condition to investigate thermal stability of saccha- ride. 2. EXPERIMENTAL 2.1. MATERIALS D(+)-glucose used in the experiment starting material was purchased from Wako Pure Chemials Industries Ltd. Regents used for products analysis were D(-)-fructose, DL-lactic acid, formic acid and acetic acid also provided by Wako Pure Chemicals Industries Ltd. 5-hydroxymethyl-2-furfural (5-HMF) and glycolic acid were from Sigma-Aldrich Co. The other reagents, such as 1,6-anhydro-β-D-glucose and 2-furfural, were obtained from Tokyo Chemical Industry Co., Ltd. and Kishida 589