【作者】 董博宇；

【导师】 肖冬光；

【作者基本信息】 天津科技大学 ， 生物化工， 2009， 硕士

【摘要】 本文以玉米芯中的半纤维素和纤维素为生产原料,尝试了三种生产燃料乙醇的工艺,将其分开利用产乙醇,提高了木质纤维原料的利用率。以水解液中木糖得率为考察指标,确定了玉米芯半纤维素稀酸水解条件,此条件下84.43%的半纤维素降解为木糖溶解到水解液中,木糖浓度达到29.84g/L。此外,建立了液相快速同时检测水解液中抑制性物质含量的方法,并确立了先过中和再用大孔吸附树脂的脱毒工艺,脱毒后水解液中毒性物质基本脱除掉,糖液澄清,且木糖损失仅有8%左右。接着优化了木糖液发酵的工艺参数,发酵后乙醇得率为0.413g乙醇/g木糖,占理论得率的89.8%。利用酿酒酵母对酸解后残渣中的纤维素进行同步酶解糖化发酵,优化了培养基组成和发酵条件,得到了比较高的乙醇产率0.525g乙醇／g纤维素,达到理论得率的92.59%。以木质素去除率和考察指标,确立了氢氧化钙降解木质素条件,木质素去除率达到81.20%。为了充分利用半纤维素,利用木聚糖酶将其酶解成木糖,再由休哈塔假丝酵母发酵成乙醇,优化了酶解条件和发酵条件,乙醇得率达到0.421g乙醇／g木糖,占理论得率的91.52%。接着优化了纤维素部分同步糖化发酵条件,乙醇得率达到0.522g乙醇／g纤维素,占理论产率的92.06%。正交法优化了白腐菌降解木质素工艺条件,木质素去除率达到42.70%。优化了木聚糖酶酶解条件和木糖酶解液发酵条件,乙醇得率可达到0.424g乙醇/g木糖,占理论得率的92.20%。接着优化了纤维素部分同步糖化发酵条件,乙醇得率达到0.507g乙醇/g纤维素,占理论产率的89.42%。对玉米芯经过三种工艺生产燃料乙醇的产出状况进行了总结。10g玉米芯经酸解生产工艺最终可得到3.2139g乙醇,经氢氧化钙预处理的生产工艺最终可得到2.8159g乙醇,经白腐菌预处理的生产工艺最终可得到2.2975g乙醇。更多还原

【Abstract】 The experiment used hemicellulose and cellulose in corn cob as raw materials source. Three processes was studied. They all made use of respectively, enhancing the output from unit lignocellulose.For technics employed diluted acid hydrolysis, the hydrolyze conditions was optimized in term of xylose yield.84.43% of hemicellulose in corn cob was degradated to xylose which dissolved in hydrolysate. The xylose concentration reached 29.84g/L. The detoxification is necessary in order to making use of xylose in hydrolysate well. First we established a quick method which can measure the content of acetic acid, furfural and 5-hydroxymethylfurfural in hydrolysate at the same time. The order and conditions of method for detoxification were choosed and optimized. After detoxification, all the inhibitive compounds were almost removed. The hydrolysate became clear and the xylose concentition reached 27.74g/L in correlative to 8% of the xylose losing. Followly the xylose was fermented to ethanol with Candida shehatae. The conditions of fermentation contains. The ethanol yield reached 0.413g/g (ethanol/xylose), which is 89.8% of theoretical yield. The cellulose in residues employed pretreatment and enzyme hydrolysis was fermented to ethanol through simultaneous saccharification fermentation with Saccharomyces cerevisiae, the conditions was optimized in term of ethanol yield. The ethanol yield reached 0.525g/g (ethanol/cellulose), which is 92.59% of theoretical yield.For Ca(OH)2 and white-rot fungi delignification technics, in terms of delignification the conditions of pretreatment with Ca(OH)2 were optimized and the conditions with white-rot fungi. In order to taking full advantage of hemicellulose, we hydrolyzed it to xylose with xylanase. The coditions of enzyme hydrolysis were optimized in term of xylose yield. The conditions of fermentation from xylose in enzyme hydrolysate to ethanol with Candida shehatae were optimized, containing loading of enzyme 800U/g and time 60h. The ethanol yields reached 0.421 and 0.424g/g (ethanol/xylose), which is 91.52% and 92.20% of theoretical yield. The SSF conditions of cellulose in two residues were optimized in term of ethanol yields. After SSF, The ethanol yields reached 0.522 and 0.507g/g (ethanol/cellulose), which is 92.06% and 89.42% of theoretical yield.The output of ethanol were summarized employed three diffierent technics.3.2139, 2.8159 and 2.2975g ethanol per lOg corn cob were obtained under the technics of diluted H2SO4 hydrolysis, Ca(OH)2 pretreatment and biodegradation by white-rot fungi.更多还原