Research On Quality Storage Of Corn Stalk And Efficient Hydrolysis Of Cellulose

In order to realize the large-scale biogas production technology with the dry cornstalk, it is necessary to solve some problems, such as the low fermentation efficiency,poor utilization and high cost of pretreatment. This research investigated a newsilaging method of corn stalk, and explored an effective pretreatment method whichcould convert all cellulose and hemicelluloses in dry corn stalk to matrix directly usedby the methane fermentation bacteria. It could solve the key problems during biogasproduction and realize efficient utilization of corn stalk, which is to achieve futher thegoal that converting corn stalk into resources effectively. The contents and mainconclusions of this research are as follows:（1） Using different methods to silaging the fresh corn stalk, restraininglignifications of corn stalk in the natural drying process, to keep the watersoluble-carbohydrates in the fresh corn stover. The quality of the silage methods wereevaluated by determining the varieties of chemical composition in corn stalk duringsilage period. The results showed that the content of Klason lignin for corn stalksilage decreasing29.4%-43.7%compared with air-dried corn stalk.（2） Air-dried corn stalks were treated with different concentration of NaOHsolution. The lignin removal effects were evaluated by the concentration of NaOHsolution, response time and temperature. A central composite design with threeindependent variables （NaOH concentration, reaction time and reaction temperature）was employed to research their simultaneous effects on three responses includingcellulose and hemicelluloses recovery, the ratio of delignification. Further, theexperimental results were optimized, and the optimum conditions were: NaOHconcentration0.83wt%, reaction temperature34℃and time16h. Under thiscondition, the lignin removal rate was51%, cellulose content and hemicellulosecontent of the solid residue were50.38wt%and25.6%, respectively. In addition, thelignin removal effect of corn stover by different additives and sodium hydroxidemixed solution were studied, it is concluded that the optimum combination was0.83wt%NaOH+0.1wt%urea.（3） HNO₃, HCOOH, FeCl₃and AlCl₃were chosen as catalysts to determine theireffects on cellulose hydrolysis in residues after part of lignin in the dry corn stalk was removed. The results showed that the cellulose hydrolysis effects were higher in260℃than those in220℃. And the HCOOH and FeCl3were the most efficientcatalysts for cellulose hydrolysis. Then it is further researched that effects of theHCOOH and FeCl3concentrations for cellulose hydrolysis, the results showed that,the cellulose hydrolysis was91.6%when the reaction temperature was260℃,reaction time was2min and FeCl3concentrations was0.01M, while the cellulosehydrolysis was93.7%when the HCOOH concentration was4wt%as the samereaction conditions. In addition, the two step hydrolysis method was compared withthe only one step hydrolysis method, and it is showed that the catalyst amount of twosteps pretreatment method was decreased as32.1%, after mixing the two stepshydrolysate, it was more suitable for subsequent anaerobic fermentation biogasproduction.