Catalytic Hydrothermal Saccharification of Rice Straw Using Mesoporous Silica-based Solid Acid Catalysts

Catalytic hydrothermal saccharification of rice straw was carried out in the presence of sulfonated mesoporous silica (SBA-15) -based solid acid catalysts. Effects of reaction time, reaction temperature and weight ratio of solid acid catalyst to rice straw on the saccharification of rice straw were investigated. With increasing reaction time and reaction temperature, the yield of monosaccharide initially increased and then decreased, but the yield of byproducts increased. With increasing weight ratio of solid acid catalyst to rice straw up to 25 %, the yield of monosaccharide initially increased and then remained almost constant. The yield of monosaccharide was 38 % for the saccharification of rice straw carried out at 180 °C for 1 h with the weight ratio of rice straw/distilled water/solid acid catalyst equal to 3/30/0.5 (g/g/g). The composition of rice straw and crystallinity index of cellulose in rice straw before and after the saccharification were determined, respectively. Based on the composition analysis, most xylan and glucan derived from hemicellulose were decomposed, but glucan derived from cellulose was little decomposed via catalytic hydrolysis at 180 °C and below. On the other hand, xylan and glucan derived from hemicellulose were almost completely decomposed, and part of glucan derived from cellulose was also decomposed at 200 °C and above. At the same time, some ash and lignin in rice straw were removed in all the reactions.