两步法预处理制备生物质燃料乙醇

为了扩展燃料乙醇制备的预处理工艺的发展方向,该文针对燃料乙醇制备的2种新预处理方法——半纤维素分离两步预处理法和木质素分离两步预处理法进行了试验研究。分别以能源植物柳枝稷和农业废弃物玉米秸秆为原料,考查了这2种方法对酶水解过程中糖产量的影响。结果表明,半纤维素分离两步预处理法对柳枝稷的较优处理条件为:第一步预处理用3%质量分数的过氧化氢溶液在50℃处理16h,第二步预处理用去离子水在121℃处理30min,最终酶水解可获得89%的纤维素转化率;木质素分离两步预处理法对玉米秸秆的较优处理条件为:第一步预处理用碱性乙醇溶液(1%质量分数氢氧化钠和70%质量分数乙醇)在80℃处理2h,第二步预处理为去离子水在135℃处理30min,最终酶水解可获得83%的纤维素转化率;扫描电镜观察,柳枝稷和玉米秸秆的纤维束均被破坏,纤维素酶的作用面积得到提高。同时,分离提取了部分半纤维素和木质素,可以回收提纯,应用于高附加值化学产品的制备。这一结果表明,这2种方法为实现燃料乙醇制备工程工业化提供依据。

Investigation of two-step pretreatment method for production of ethanol from lignocellulosic biomass

For developing new pretreatment methods of fuel ethanol production, hemicellulose separation two-step pretreatment method and lignin separation two-step pretreatment method were investigated using switchgrass and corn stover. In the hemicellulose separation two-step pretreatment, a cellulose digestibility of 89% was obtained (Step 1 with the condition of 2%wt H2O2, 50oC and 16 h; Step 2 with the condition of 121oC and 30 min), while in the lignin separation two-step pretreatment, the highest cellulose digestibility of corn stover was 83% (Step 1 with the condition of 1%wt NaOH, 70%wt ethanol solution, 80oC and 2 h; Step 2 with the condition of 135oC and 30 min). SEM micrographs showed that the surface of biomass had been altered and the accessibility of enzymes had been improved. Hemicellulose and lignin separated from the feedstock could be recovered for the production of value-added products. The results indicate that these two pretreatment methods have a promising future, and are very helpful for the industrialization of fuel ethanol production.