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木质纤维原料生物转化燃料乙醇的研究进展 总被引:31,自引:2,他引:31
木质纤维生物量能够用来生产一种可替代有限的石油产品的能源——乙醇。木质纤维的转化主要分两个步骤木质纤维生物量中纤维素水解生成还原糖;糖发酵成乙醇。基于目前的技术,木质纤维原料生产乙醇的主要问题是得率低、水解成本高。促进木质纤维水解的方法包括木质纤维原料预处理脱除木素和半纤维素;纤维素酶的优化;同步糖化发酵法(SSF)。 相似文献
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木质纤维素转化为燃料乙醇的研究进展 总被引:26,自引:0,他引:26
以木质纤维素为原料生产燃料乙醇的生物转化方法包括预处理、酶水解和发酵过程,对这些过程中的技术进展以及解决现存问题的方法进行了评述。氨法爆破技术是较好的预处理方法,超声波、微波处理等新技术有助于改善酶水解。阐述了酶水解机理、纤维素酶的生产以及酶水解过程的优化方法。指出固定化酶糖化发酵技术在生物转化木质纤维原料技术中的前景广阔;选择合适的发酵方法,优化发酵过程,以及解决抑制问题对于提高乙醇产率尤为重要;利用基因重组技术构建旨在发酵混合糖的重组菌对于生产生物乙醇具有里程碑意义。 相似文献
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采用分段酶水解木质纤维原料的方法,以NaOH-Fenton试剂预处理桑木为原料,通过在反应过程中及时移除葡萄糖和纤维二糖,减轻产物的抑制作用,最终达到提高酶水解得率和缩短酶解反应时间的目的。实验结果表明:纤维素酶用量为15FPIU/g(以纤维素计,下同)时,在三段(8+8+8h)水解过程中,经第一段水解,纤维素酶反应速率从1.25g/(L·h)提高到2.21g/(L·h),第二段水解后,酶反应速率为1.54g/(L·h),比未分段水解的酶反应速率提高了73%;当纤维素酶用量为40FPIU/g时,三段(8+8+8h)水解得率增至88.08%;三段(8+8+8h)水解充分利用了酶解残渣上的结合酶进行后续水解。对纤维素酶在预处理桑木上的吸附情况进行研究,发现桑木经NaOH-Fenton试剂预处理后,对纤维素酶的最大吸附量为8.08mg/g,预处理增加了纤维素酶与桑木间的吸附位点。 相似文献
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木质纤维素转化燃料乙醇一般需要经过原料预处理、酶水解和发酵过程。由于木质纤维原料化学结构复杂、直接酶解效率非常低,一般在酶水解之前需要进行适当的预处理以打破其致密结构,增加纤维表面积,提高后续纤维素酶的可及性。预处理程度直接影响纤维底物后续酶水解的效果。本文在木质纤维素常用预处理技术分析的基础上,重点讨论了3种相对高效的预处理技术:微波辅助离子液体预处理、两阶段深度共熔溶剂(DES)预处理和氯化铁预处理技术,分析了它们的优势、不足及发展现状。文中指出微波辅助离子液体预处理可有效解构木质素和半纤维素,破坏纤维素结晶区域,利于后续酶解,但微波加热过程会使离子液体分解和部分底物碳化。两阶段DES预处理可有效提高酶水解效率,但是预处理后原料中残留的DES可能会对后续反应中纤维素酶和微生物产生抑制作用。氯化铁预处理可有效破坏木质素与碳水化合物间的结合键,脱除底物中的半纤维素,而对木质素和纤维素降解较少,具有很好的发展前景。由于单一预处理技术的局限性,寻求低成本高效的联合预处理技术将是未来重点发展的方向。 相似文献
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本文对木质纤维材料的化学组成、结构特点,纤维素酶和半纤维素酶及影响酶水解的关键因素,如产物抑制、酶学特性、木质素的存在、表面活性剂的使用、酶的回收等进行了综述,对高效酶水解制取发酵糖技术的研究进行了展望。 相似文献
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纤维素酶水解农田纤维素废弃物生产还原糖的研究 总被引:2,自引:0,他引:2
以不同农田纤维素废弃物为原料,利用纤维素酶水解生产还原糖。考察了反应时间、底物浓度、酶用量、反应温度及反应pH值等因素对纤维素酶水解农田废弃物生产还原糖的影响,确立了各自的最适反应条件。 相似文献
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从原料预处理技术、纤维素酶技术、水解发酵工艺以及原料的综合利用技术等几个方面,对制约木质纤维素乙醇的技术难点进行了分析与讨论。 相似文献
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Mahendra Rai Avinash P. Ingle Raksha Pandit Priti Paralikar Jayanta Kumar Biswas Silvio Silverio da Silva 《Catalysis Reviews》2019,61(1):1-26
Catalytic conversion (hydrolysis) of carbohydrate polymers present in the lignocellulosic biomass into fermentable sugars is a key step in the production of bioethanol. Although, acid and enzymatic catalysts are conventionally used for the catalysis of various lignocellulosic biomass, recently application of immobilized enzymes (biocatalysts) have been considered as the most promising approach. Immobilization of different biocatalysts such as cellulase, β-glucosidase, cellobiose, xylanase, laccase, etc. on support materials including nanomaterials to form nanobiocatalyst increases catalytic efficacy and stability of enzymes. Moreover, immobilization of biocatalysts on magnetic nanoparticles (magnetic nanobiocatalysts) facilitates easy recovery and reuse of biocatalysts. Therefore, utilization of nanobiocatalysts for catalysis of lignocellulosic biomass is helpful for the development of cost-effective and ecofriendly approach. In this review, we have discussed various conventional methods of hydrolysis and their limitations. Special emphasis has been made on nanobiocatalysts used for hydrolysis of lignocellulosic biomass. Moreover, the other most important aspects, like nanofiltration of biomass, conversion of lignocellulose to nanocellulose, and toxicological issues associated with application of nanomaterials are also discussed. 相似文献
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酶解糖化是木质纤维素材料制备生物质乙醇的关键环节,因此提高稻秆等木质纤维素材料的酶解糖化效率具有重要意义。以稻秆为原料,采用表面活性剂耦合离子液体为预处理方法,考察预处理温度、时间、表面活性剂的添加比例对稻秆酶解的影响。结果表明,预处理温度为110℃、时间为60 min、表面活性剂添加比例为1%,稻秆的酶解效果最佳,与单独离子液体处理的稻秆相比,纤维转化率可提高8%~15%。同时分别通过稻秆成分分析、FTIR、XRD、SEM等对预处理前后的稻秆结构进行表征,证实预处理后酶解效率提高的合理性。 相似文献
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Elmer Ccopa Rivera Sarita Cândida Rabelo Daniella dos Reis Garcia Rubens Maciel Filho Aline Carvalho da Costa 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2010,85(7):983-992
BACKGROUND: The efficient production of a fermentable hydrolyzate is an immensely important requirement in the utilization of lignocellulosic biomass as a feedstock in bioethanol production processes. The identification of the optimal enzyme loading is of particular importance to maximize the amount of glucose produced from lignocellulosic materials while maintaining low costs. This requirement can only be achieved by incorporating reliable methodologies to properly address the optimization problem. RESULTS: In this work, a data‐driven technique based on artificial neural networks and design of experiments have been integrated in order to identify the optimal enzyme combination. The enzymatic hydrolysis of sugarcane bagasse was used as a case study. This technique was used to build up a model of the combined effects of cellulase (FPU/L) and β‐glucosidase (CBU/L) loads on glucose yield (%) after enzymatic hydrolysis. The optimal glucose yield, above 99%, was achieved with cellulase and β‐glucosidase concentrations in the ranges of 460.0 to 580.0 FPU L?1 (15.3–19.3 FPU g?1 bagasse) and 750.0 to 1140.0 CBU L?1 (2–38 CBU g?1 bagasse), respectively. CONCLUSIONS: The dynamic model developed can be used not only to the prediction of glucose concentration profiles for different enzymatic loadings, but also to obtain the optimum enzymes loading that leads to high glucose yield. It can promote both a successful hydrolysis process control and a more effective employment of enzymes. Copyright © 2010 Society of Chemical Industry 相似文献
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The cost of cellulase is a major factor limiting the enzymatic hydrolysis of cellulosic biomass. Thus, immobilization of cellulase would be an important advancement. Lignophenol is a lignin-based functional phenolic polymer synthesized from a lignocellulosic material and a phenol derivative at ambient temperature. Cellulase derived from Trichoderma reesei is easily immobilized by softwood and hardwood lignocresol simply by mixing to produce a water-insoluble lignophenol-cellulase complex. Enzymatic hydrolysis performances of cellulases immobilized on lignocresols are approximately 80–90% and 30–50% relative to that of free cellulase in the hydrolysis of carboxymethylcellulose (CMC) and filter paper, respectively. Cellulase was active enough even after adsorption on lignocresols. Limited physical contact between solid substrates and immobilized cellulase due to the presence of lignocresol seems to lead to lower enzymatic activity for solid substrates. Hardwood lignocresol-immobilized cellulase exhibits slightly higher activity than softwood lignocresol-immobilized cellulase when the same amount of cellulase is used per gram lignocresol. Although cellulase activity gradually decreases with recycling, sufficient enzymatic activity, at least for hydrolyzing soluble substrates, remains that it can be reused. 相似文献
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半纤维素作为木质纤维素的重要组分之一,通过氢键与纤维素的微纤丝结合,严重阻碍了纤维素表面与纤维素酶的接触,降低了酶解的效率。该试验以碱处理甘蔗渣作为底物,通过添加不同量的半纤维素酶去除不同比例的半纤维素。通过成分分析、X射线衍射(XRD)和扫描电镜(SEM)等手段分析添加半纤维素酶前后残渣的结构和酶解特性变化,发现随着半纤维素酶添加量的增大,残渣中木质素所占的比例逐渐增大,结晶指数逐渐增大,电镜表面沟壑逐渐加深,纤维束之间结构变得疏松。以半纤维素酶处理过的甘蔗渣作为底物,按照5FPU/g底物加入纤维素酶水解72h,与不添加半纤维素酶对照组相比,添加1600U/g半纤维素酶处理的试验组木聚糖的转化率提高了74.24%,葡聚糖转化率提高了35.30%。通过半纤维素酶添加可以有效促进纤维素酶解过程的进行,节约反应时间提高酶解转化率。 相似文献
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麦草是一种具有很大潜力的制取生物乙醇的可再生木质纤维素原料。文章探讨了碳酸钠预处理预浸时间、保温时间、碳酸钠用量对麦草化学成分及酶水解效率的影响。结果表明,延长碳酸钠预处理保温时间对木质素脱除无明显影响,但浆料得率和酶水解总糖转化率有所下降;合理的预浸时间为30 min,继续延长预浸时间对预处理浆料酶水解总糖转化率无促进作用;增加预处理Na2CO3用量有助于促进木质素的脱除,大部分碳水化合物保留在浆料中。在8% Na2CO3(Na2O计)用量下,麦草于80℃预浸30 min后升温至130℃,不保温所得到的浆料在纤维素酶用量为20 FPU/g(对纤维素)时,其总糖转化率为60%。 相似文献