金属离子助催化稀酸水解纤维素工艺的研究

以小麦秸秆为原料,采用正交试验考察了硫酸浓度、Fe2+浓度、反应温度和反应时间等因素对稀酸水解纤维素的还原糖得率的影响,得到了优化的纤维素水解反应工艺组合:反应温度180℃,Fe2+浓度0.0375mol/L,硫酸质量分数1%,反应时间90min。研究了Fe2+、Ni2+、Na+、Mg2+四种金属离子对稀酸水解纤维素制备还原糖的影响,结果表明,金属离子能明显提高稀酸水解纤维素的转化率和还原糖得率,其助催化作用的大小依次为:Fe2+Na+Ni2+Mg2+,Fe2+对稀酸水解小麦秸秆制备还原糖的催化效果最佳,还原糖得率最高可达73.05%,纤维素转化率达到85.79%。     

NaOH冷冻-HCl再生预处理辅助碳基固体酸水解纤维素研究

本研究以提高纤维素转化率和还原糖得率为目标,以玉米秸秆制备的碳基固体酸为催化剂,采用Na OH冷冻-HCl再生为预处理方法,考察了预处理过程中Na OH浓度及纤维素水解过程中水解温度和水解时间对纤维素水解效果的影响。结果表明,在水解温度180℃、水解时间3h、纤维素0.15g、催化剂用量0.45g的条件下,纤维素水解还原糖得率38.78%,纤维素的转化率45.6%,与相同工艺条件下未经预处理的纤维素相比,还原糖得率及纤维素转化率分别提高了30.88%和31.1%,说明Na OH冷冻-HCl再生处理纤维素能够辅助提高碳基固体酸催化水解纤维素的效率。     

秸秆预处理方法的筛选

农作物秸秆组分结构特殊,秸秆中的木质纤维素很难被酸和酶降解。解决了木质素的降解问题,就能提高秸秆的降解性能。研究开发适宜的预处理技术是一种重要的降解木质素方法。通过预处理技术,使木质纤维素首先降解成简单成分,从而有利于随后的厌氧消化过程。通过试验,分析了不同的预处理方法对秸秆组分降解率的影响和污泥预处理方法的筛选,最终得出：最佳预处理方法为稀硫酸预处理法,处理条件如下：硫酸浓度：0．7％;处理温度：121℃;预处理时间：1h。     

吐温-80及碱预处理对饲用稻草木质素含量和纤维素酶解产糖的影响

探讨了添加1‰吐温-80非离子表面活性剂和不同浓度碱预处理对稻草秸秆木质素及纤维素的影响,并对预处理前后的稻草进行了X射线衍射光谱(XRD)分析,从结晶度的变化综合分析了预处理对纤维素酶解的影响。实验结果表明:在30℃下添加1‰吐温-80非离子表面活性剂时,用4%NaOH预处理稻草秸秆,木质素含量降至6.5%(较未处理稻草下降了41.9%),灰分值仅占6.9%,具有较好的粗饲料价值;在121℃(0.1 MPa)下添加1‰吐温-80非离子表面活性剂时,用4%NaOH预处理稻草秸秆,木质素含量降至2.8%(较未处理稻草下降了74.5%),酶解还原糖达到393.9 mg/g,纤维素糖化率为59.3%(较未处理稻草提高了2.4倍)。XRD分析显示,在较温和的条件下,低浓度碱预处理稻草秸秆,对纤维素结晶区带来的影响相对于无定形区弱,不足以引起纤维素结晶度的降低。     

碱性臭氧预处理对稻草秸秆酶水解的影响

以稻草秸秆为原料经碱性臭氧预处理后进行酶水解,研究了处理前后稻草秸秆半纤维素、纤维素、木质素含量的变化,通过测定酶水解还原糖含量来判断预处理的效果。结果表明,碱性臭氧预处理与碱预处理相比,在稻草秸秆木质素含量与降解上没有什么差异,但酶水解糖化效果更优。经O3/2%NaOH预处理过的稻草秸秆,在pH值5.0、酶用量31.2mg.（g底物）-1、45℃条件下酶水解120h时,还原糖含量达到了902mg.（g稻草秸秆）-1,糖化率达到了92.57%。     

碳酸钠预处理对麦草酶水解糖化的影响

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%。     

稀酸催化小麦秸秆分步水解研究

利用农作物秸秆水解产物酿造酒精是发展可再生能源的一条重要途径,促进秸秆组分中半纤维素和纤维素的高效、低成本水解转化是实现这一途径的关键和瓶颈。以小麦秸秆为原料,稀硫酸为催化剂,研究了秸秆组分中半纤维素和纤维素的分步水解工艺,通过正交试验优化了酸浓度、原料固含量、反应时间和反应温度等工艺条件,在优化的分步水解工艺条件下原料转化充分,还原糖得率较高。     

NaOH/AQ预处理对玉米秸秆脱木质素及酶解性能的影响

对玉米秸秆进行氢氧化钠/蒽醌（NaOH/AQ）去木质化预处理,考察了预处理温度、时间和NaOH用量对玉米秸秆脱木质素程度的影响,并探讨了脱木质素程度对提高预处理后物料酶解性能的影响。L₉（3⁴）正交试验得出较适宜预处理工艺条件为：温度160℃,时间60 min,NaOH用量（以绝干原料质量计）2.8%;其他条件为AQ用量0.05%,固液比1：5（g：mL）,此时木质素脱除率为75%,酶解后聚糖转化率达到73.79%。随着物料脱木质素程度的提高,其酶解效率相应增加;当木质素脱除率达到一定程度后,预处理后的聚糖转化率达到最大值,继续提高木质素脱除率,聚糖转化率反而降低。响应面优化的酶水解工艺条件为纤维素酶用量30 FPU/g,β-葡萄糖苷酶10 IU/g,反应时间72 h,温度50℃,底物质量分数2.5%,此时还原糖得率为85.62%。对酶解液进行HPLC分析,酶解液中的葡萄糖质量浓度为14.83 g/L,木糖质量浓度为4.83 g/L。XRD分析显示,预处理前后纤维素的晶型没有变化,而结晶度由31.40%提高至46.91%,表明物料中木质素和半纤维素发生了不同程度的溶出。     

不同预处理方法对玉米秸秆吐温-80/酶水解的影响

比较了稀硫酸、氢氧化钠、氨水和氢氧化钙4种预处理方法对玉米秸秆吐温-80/酶水解的影响,结果表明:氢氧化钠预处理方法效果最佳,得到的总还原糖产率比未处理时提高了10.7倍.其红外光谱和广角X-谢线衍射谱图表明:经氢氧化钠预处理后,玉米秸秆中的木质素含量降低了62%,纤维素的结晶度也有所降低.     

微波辐射对硫酸催化稻草水解的促进作用

研究了微波辐射对硫酸催化稻草水解的促进作用.考察了微波辐射功率、辐射时间、硫酸质量分数及每升硫酸溶液中稻草添加量对还原糖得率的影响.与常规酸水解比较,微波辐射可显著加快水解速率,缩短糖化时间.采用正交试验法对微波辐射下稻草硫酸水解条件进行了优化,最佳条件为:微波功率280 W,辐射时间30 min,硫酸质量分数25%,每升硫酸溶液中稻草添加量30 g,还原糖得率达到26.5%.     

木质纤维原料组分分离的研究

从木质纤维原料预处理对微生物转化的必要性和回收利用半纤维素、木质素意义两个方面分析了木质纤维原料组分分离的必要性。木质纤维原料组分分离意味着木质纤维原料的精制,不是把木质纤维原料仅作为纤维素单一资源看待,而是把它视为一种多组分物料,将木质纤维原料精制成为具有一定纯度的各种组分,并分别加工成有价值的产品,这也是生物量全利用对于木质纤维原料预处理提出的新要求,赋予新的哲理思想。根据生物量全利用的要求,提出了木质纤维原料组分分离技术的新定性评价标准。根据利用汽爆和乙醇萃取法联合对麦草组分分离的研究结果,可提出一条经济可行的麦草组分分离的工艺过程,半纤维素和木质素回收率分别达到了80%和75%,纤维素酶解率达90%以上。     

低共熔溶剂预处理杨木水解渣拆解木质素

为高效去除木质纤维素中的木质素,获得富含纤维素的底物,实现木质纤维素组分的单一分离与组分全利用,制备合成了6种三元低共熔溶剂（deep eutectic solvent, DES）,利用DES预处理已去除半纤维素的杨木水解渣,研究了6种低共熔溶剂对木质素去除和纤维素保留的影响,并优化获得了最佳的预处理工艺参数。结果表明,6种DES中苄基三乙基氯化铵-乙二醇-氯化铁（T-EG-Fe）的预处理效果最优,木质素去除率为80.46%,纤维素保留率为90.81%。优化得到T-EG-Fe预处理杨木水解渣最佳工艺条件为：反应固液比为1∶15,反应温度为130℃,反应时间为5h,在最优条件下预处理得到的固体残渣中纤维素质量分数为92.78%,木质素质量分数为5.33%。T-EG-Fe具有高效拆解木质素的潜力,在木质纤维素预处理过程中具有一定的应用价值。     

Enzymatic hydrolysis from carbohydrates of barley straw pretreated by ionic liquids

BACKGROUND: Lignocellulosic biomass offers many potential advantages in comparison with the traditionally used sugars or starchy biomass since it is very widely available and does not compete with food and feed production. The abundance and high carbohydrates content of barley straw make it a good candidate for bioethanol production in Europe. Since biomass must be pretreated before enzymatic hydrolysis to improve the digestibility of both the cellulose and the hemicellulose biomass, the use of ionic liquids (IL) has been proposed as an environment‐friendly pretreatment of biomass. RESULTS: Different pretreatment conditions were investigated to determine the effects of the experimental conditions (temperature and time) on the enzymatic digestibility of pretreated material. The pretreatment of barley straw with 1‐ethyl‐3‐methyl imidazolium acetate treatment resulted in up to a 9‐fold increase in the cellulose conversion and a 13‐fold increase in the xylan conversion when compared with the untreated barley straw. CONCLUSION: Ionic liquid pretreatment of barley straw at 110°C for 30 min, followed by enzymatic hydrolysis, leads to a sugar yield of 53.5 g per 100 g raw material. It is then ready available for conversion into ethanol and is equivalent to more than 86% from potential sugars. The increase in saccharification was possible due to rupture of the lignin–hemicellulose linkages by treatment with 1‐ethyl‐3‐methyl imidazolium acetate. © 2012 Society of Chemical Industry     

Enhanced enzymatic hydrolysis of rice straw pretreated by alkali assisted with photocatalysis technology

BACKGROUND: The fermentable sugars in lignocellulose are derived from cellulose and hemicellulose, which are not readily accessible to enzymatic hydrolysis because of their biological resistance, so that pretreatment of lignocellulose is needed for this process. In this work, a novel lignocellulose pretreatment method using alkali solution assisted by photocatalysis was investigated. RESULTS: The reaction conditions of nano‐TiO₂ dosage and photocatalysis time were optimized at 2 g L^?1 and 1 h, respectively. After pretreatment under these conditions, cellulose in rice straw was increased from 37.5% to 71.5%, and lignin decreased from 18.5% to 9.0%. The results of X‐ray diffraction (XRD), Fourier transform infrared (FT‐IR) and scanning electron microscopy (SEM) analysis showed that the physical properties and microstructure of the straw were changed by this pretreatment, which favored the following enzymatic hydrolysis. The enzymatic hydrolysis rate of the straw pretreated using this technology was verified to be 73.96%, which was 2.56 times higher than that obtained with the alkali procedure. CONCLUSION: The proposed photocatalysis pretreatment technology was more efficient at degrading the lignin and hemicellulose in rice straw than alkali pretreatment, making it more readily available for the following enzymatic hydrolysis process. Copyright © 2009 Society of Chemical Industry     

麦草蒸汽爆碎处理的研究──Ⅰ.影响麦草蒸汽爆碎处理因素及其过程分析

在组分分离新概念的指导下,对影响安享蒸汽爆碎处理因素及其过程进行了分析。在麦草沟爆过程中,不仅具有半纤维素自体水解作用,而且还有麦草木质素易降解性。     

稻草秸秆3种预处理方法的比较

底物w(纤维素)和w(半纤维素)是木质纤维素转化为乙醇、乳酸和其他化学品最为重要的因素。为了提高底物w(纤维素)、w(半纤维素)和糖化得率,该文采用稀硫酸、氢氧化钠和氢氧化钠联合过氧乙酸等3种化学方法对稻草秸秆进行了预处理。结果表明,用ρ(NaOH)=20 g/L的碱液于85℃与ρ(过氧乙酸)=60 g/L酸液于75℃联合处理秸秆时,秸秆w(纤维素)从41.5%上升到81.5%,w(半纤维素)下降为13.7%,纤维素酶酶解48 h葡萄糖质量浓度达37.7 g/L,木糖质量浓度为12.8 g/L;用ρ(NaOH)=20 g/L碱液于121℃处理秸秆时,秸秆w(纤维素)为66.3%,w(半纤维素)为20.2%,酶解60 h后葡萄糖质量浓度为33.5 g/L,72 h木糖质量浓度为15.1 g/L。     

固态发酵中纤维素基质降解过程初步研究

利用斜卧青霉(Penicillium decumbens JUA10)对汽爆麦草和淀粉质的混合基质进行固态发酵，通过分析各种成份及酶活力变化，研究了各成份的降解速率，并探讨了纤维素、半纤维素降解与纤维素酶、半纤维素酶酶活力的关系. 纤维素基质固态发酵中木质纤维素的降解过程实际是同步糖化发酵过程，还原糖不会积累形成对纤维素酶、半纤维素酶的反馈抑制；纤维素降解与纤维素酶的酶活性、半纤维素的降解与半纤维素的酶活性不成正比. 木质纤维素的降解难主要是木质纤维素结构造成的. 半纤维素的降解甚至比纤维素降解更慢，淀粉容易降解，木质素几乎不降解.     

浅谈秸秆类废弃物制备燃料乙醇的工艺

秸秆类废弃物类物质是地球上一种含量极其丰富的可再生资源,其主要由纤维素、半纤维素和木质素组成。这种废弃物类物质在经过预处理、水解和发酵工艺后,可以用来生产变性燃料乙醇。文章针对这几个关键工艺步骤进行了描述,并探讨了目前有关方面的最新进展。     

Preparation of microcrystalline cellulose from rice straw under microwave irradiation

Crude cellulose was isolated from rice straw and then converted into microcrystalline cellulose (MCC) via partial hydrolysis. Both the isolation and partial hydrolysis were carried out under microwave. Rice straw was successively pretreated with alkaline and acid solutions before hydrolysis. Lignin and silica were almost removed but partial removal of hemicellulose in dilute alkali solution, and the residual hemicellulose was further removed in dilute acid solution. The total removal rates of hemicellulose, lignin and silica reached up 92.0%, 98.5%, and 96.8%, respectively. The cellulose content of 93.6 wt % in MCC was given by partial hydrolysis of crude cellulose isolated from rice straw. The comparison between microwave irradiation and traditional heating method was also investigated. Compared to traditional heating method, similar results were obtained while milder conditions, including shorter time and lower temperature, were required. An effective microwave‐assisted and energy‐efficient methodology using rice straw as the alternative source of cellulose fiber was developed. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44901.