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提出了一个木质纤维素生物质预处理的全绿色加工过程.以玉米秸秆和玉米芯为原料,以超临界CO_2和超声偶合法对木质纤维素进行预处理.超临界CO_2预处理条件为:压力15-25 MPa,温度120_170℃,含水量50%,反应时间0.5_4 h.超声场功率600W,温度80℃,作用时间2-8 h.用纤维素酶水解反应获得的还原糖总量来评价预处理效果.结果表明,单纯超临界CO_2和超临界CO_2偶合超声预处理都能够提高生物质水解反应还原糖产量.对于玉米芯,超临界CO_2预处理(170℃,20 MPa,3 0min)后,还原糖产率为62%(未预处理的为12%).对于玉米秸秆(170℃,20 MPa,2.5 h),还原糖产率为46.4%.对于玉米芯,超临界CO_2偶合超声预处理(600 W,80℃下超声处理6 h,然后用170℃,20 MPa超临界CO_2预处理30 min)后,还原糖产率为87%.对于玉米秸秆,超临界CO_2偶合超声预处理(600 W,80℃下超声处理8 h,然后用170℃,20 MPa超临界CO_2预处理1 h)后,还原糖产率为25.5%.与未处理生物质相比,X射线衍射结果表明玉米秸秆和玉米芯在超临界CO_2和超声预处理后其结晶度没有明显变化.扫描电镜分析则发现木质纤维素的表面积显著增加.
A whole green process of pretreatment of lignocellulosic biomass was proposed.The lignocellulose was pretreated by supercritical CO_2 and ultrasonic coupling with corn stalks and corn cob as raw materials.The conditions of supercritical CO_2 pretreatment were as follows: pressure 15-25 MPa, temperature 120-170 ℃, water content 50%, reaction time 0.5_4 h, ultrasonic field power 600W, temperature 80 ℃, action time 2-8 h. The total amount of reducing sugar obtained by cellulase hydrolysis was used to evaluate The results showed that both supercritical CO_2 and supercritical CO_2 preconditioning could increase the yield of reducing sugar in biomass hydrolysis.For corn cob, supercritical CO_2 pretreatment (170 ℃, 20 MPa, 30 min) , And the yield of reducing sugar was 62% (12% without pretreatment) .For corn stover (170 ℃, 20 MPa, 2.5 h), the yield of reducing sugar was 46.4% .For corn cob, supercritical CO2 coupled ultrasound (600 W, sonicated at 80 ℃ for 6 h, then pretreated with 170 MPa, 20 MPa supercritical CO 2 for 30 min), the yield of reducing sugar was 87%. For corn stalk, supercritical CO 2 coupled ultrasonic pretreatment 600 W, sonicated at 80 ℃ for 8 h and then pretreated with supercritical CO 2 at 170 ℃ and 20 MPa for 1 h, reducing sugar Rate of 25.5% .Compared with the untreated biomass, X-ray diffraction results showed that corn stalks and corn cob did not change significantly after supercritical CO_2 and ultrasonic pretreatment.The scanning electron microscopy analysis showed that the surface area of lignocellulose was significant increase.