Effects Of Different Pretreatment Methods On Enzymatic Hydrolysis Of Bamboo To Cellulosic Ethanol

As the global petroleum resources are depleted and the pressure of the carbon reduction, theR&D of bioenergy as a clean renewable energy begins to be received extensive attention in the world.The pretreatment and enzymatic hydrolysis of cellulosic ethanol as a new type alternative fuel is thekey technology.In this thesis, bamboo as raw materials are treated with physical and chemical pretreatment likeammonia fiber explosion (AFEX), steam explosion, hot water and many combined pretreatment likeAFEX with H2O2and steam explosion with dilute acids. The conversion rate and the total yield ofsugars of enzymatic hydrolysis is detected to ensure the effects of pretreatments. In this study, theresults of different type’s bamboo, corn stover and poplar are comparative analyzed. Raw materialcomposition, enzymatic hydrolysis and sugars determination are mainly based on the experimentalanalysis procedures of the national renewable energy laboratory (NREL). The improvement andoptimization of pretreatment processes involve parameters of raw material types, moisture content,pretreatment strength (temperature, pressure), residence time, and ammonia loading.The conclusions in this thesis are as follow:(1) The pretreatment process for biomass feedstock has significant selectivity; the effect of sametreatment is different on various raw materials. This may be related to the chemical composition of theraw materials, the surface density and lignifications. It is especially important about how to select thehigh carbohydrate and low lignifications of the raw materials. The carbohydrate of bamboo is high,but it is more difficult of pretreatment than crop straw, and the significant influence of enzymatichydrolysis rate is depend on the age of bamboo.(2) The effects of multi-factors combined processes is more excellent than single-factor ones’,and the combined pretreatments of raw material biomass are the important ways to improve the effectof enzymatic hydrolysis.(3) The correct analysis of sugars rate from biomass must be through mass balance, because highintensity of the pretreatment will lead to monosaccharide be decomposed.(4) Partial results of optimized pretreatment processes and the yield of enzymatic hydrolysis:1)The optimized conditions of AFEX pretreatment process for one-year Moso bamboo: at60%moisturecontent and2:1ammonia loading, set pretreatment temperature at150℃for10mins. The conversion rate of glucan and xylan is relative52.35%and91.66%, and we can get monosaccharides42.6gfrom100g bamboo of dry basis, there is6.1-fold increase in sugar yield compared to the untreatedhydrolysate (UT). In similar conditions, three-year Sinocalamus oldhami bamboo is1.8-fold yield ofUT.2) Combined AFEX pretreatment (H2O2) with optimized conditions: at80%moisture content(adding H2O2) and2:1ammonia loading, set pretreatment temperature at150℃for10mins. Theconversion rate of glucan and xylan is relative69.92%and94.23%, and we can get monosaccharides49.1g from100g bamboo of dry basis, which is7.1-fold yield of UT, closing to76%of total sugartheoretical yield.3) The optimized conditions of AFEX pretreatment process for corn stover: at60%moisture content and1:1ammonia loading, set pretreatment temperature at90℃for5mins. Theconversion rate of glucan and xylan is relative87.43%and96.53%, getting monosaccharides61.9gfrom100g bamboo of dry basis.4) The optimized conditions of combined AFEX pretreatment forpoplar wood: at60%moisture content (adding H2O2) and2:1ammonia loading, set pretreatmenttemperature at90℃for10mins. The conversion rate of glucan and xylan is relative43.24%and49.10%, getting monosaccharides24.8g from100g bamboo of dry basis.5) In the steam explosionpretreatment, the severity factor index of highest total sugars yield is3.65, when is2.1-fold yield ofUT.