8-37: Two-stage pretreatment of rapeseed straw with sodium hydroxide and sulfuric acid

Biological conversion of biomass into fuels and chemicals requires hydrolysis of the polysaccharide fraction into monomeric sugars, which can be performed enzymatically. In this study, sodium hydroxide and dilute sulfuric acid used as a catalyst for the pretreatment of rapeseed straw. The purpose of this study is to minimize the enzyme loadings in hydrolysis of pretreated rapeseed straw. The first pretreatment step with sodium hydroxide performed with relatively mild conditions; sodium hydroxide concentration of 0.5%, temperature of 140°C, and reaction time of 15 min, which can extract a little fraction of lignin and maximum xylose fraction can be retained in the biomass. And in the second step with dilute acid, the hemicelluloses monomerized into xylose and some acid soluble lignin released into hydrolyzate. The process parameters were investigated in the range of acid concentration of 3~12%, reaction temperature of 160~200°C, and reaction time of 10~30 min. The two step pretreatment reactor, which has two reservoirs designed to perform each steps in a row, was used in this experiment.