Study On Microwave Ptetreatment Of Corn Stover

The lignocellulose is the most abundant and cheapest renewable resources on the earth, and is supposed to be the most important successive resources for fuel alcohol production. Till now, the technology theory and process are investigated and cognized by researchers, but the cellulose fuel alcohol can not competed with food alcohol since the high cost of cellulose. Therefore, it has been a worldly focus to develop a new, low cost production technology for fuel alcohol production. Pretreatment is among the most costly steps, which takes up up to more than thirty percent of the whole cost and has a major influence on both prior and subsequent operations. Although several pretreatments are promising, they are still confined in laboratory because of huge energy consumed during the process. So developing a cheap and practicable pretreatment has profound meaning on biomass fuel project.Based on mechanism of microwave hydrogenation, microwave is introduced into corn stover pretreatment. Aimed at a good digestibility of the pretreated solids, several microwave absorbers were used and compared and microwave pretreatment were optimized under a microwave absorber selected. The main contents run as follows:Effect of HCl, H2SO4, NaOH, H2O, NH3H2O on microwave pretreatment was studied. The contents of lignin, cellulose and hemicellulose before and after pretreatment were measured by acid hydrolysis method. Reducing sugars after pretreatment combined with enzyme hydrolysis were tested by DNS method. According to the test results, water is determined to be the best microwave absorber in pretreatment.Microwave and water pretreatment is applied and optimized. The contents of lignin, cellulose and hemicellulose before and after pretreatment were measured by acid hydrolysis method. Glucose and xylose after pretreatment combined with enzyme hydrolysis is tested by HPLC. Ethanol after pretreatment combined with SSF is tested by GC. According to the test results, the optimal conditions were achieved, that is soaking 1g dry corn stover in 40mL water, then heated under 800W of microwave power for 4min. At the optimal conditions, 49.1% of cellulose was hydrolyzed to glucose and 21.1% of hemicellulose was converted to xylose. When the resulting pretreated solids at the optimal conditions was SSF, ethanol was achieved at 88% of theoretical yield.It can be clearly seen that un-retreated stover has a smooth and flat exterior with micro fibrils tight arrayed, while pretreated ones have a lot of micro pores on the surface. Considering the results having achieved in this paper, it is discovered that microwave pretreatment is obviously different from other known pretreatment technologies in mechanism. Almost all of the leading pretreatment technologies advanced digestibility of the solids through removal of hemicellulose or lignin, which leads to a relatively incompact structure. Microwave pretreatment enlarged the interface between solids and enzyme due to the micro pores water molecule drilled, which also facilitates enzyme entrance into interiors of solids.In this paper, microwave and water pretreatment was first applied and optimized. Micro pores on stover surface caused by microwave and water molecule was direct observed for the first time, based on which, the mechanism of microwave pretreatment was analyzed in particular. All these basic researches will have a significant value on application of lignocelluloses fuel alcohol production.