共查询到20条相似文献,搜索用时 109 毫秒
1.
《纤维素科学与技术》2015,(3):8-14
采用水抽提方法得到玉米秸秆中的水抽提液,研究水抽提液、水抽提液的稀酸水解液对水抽提玉米秸秆和稀酸预处理的水抽提玉米秸秆酶水解性能的影响。研究结果表明,与未处理玉米秸秆相比,水抽提玉米秸秆的酶水解性能有所提高,从48 h的9.88%提高到23.56%;与稀酸预处理玉米秸秆相比,稀酸预处理的水抽提玉米秸秆酶水解性能略有提高,从48 h的67.07%提高到73.44%;通过向水抽提玉米秸秆和稀酸预处理的水抽提玉米秸秆中添加水抽提液的酶水解结果表明,与未添加的空白样相比,添加水抽提液对酶水解得率的影响极小(2%以内),但水抽提液经过稀酸水解后再添加到水抽提玉米秸秆和稀酸预处理的水抽提玉米秸秆中,可以发现与未添加的空白样相比,酶水解得率大幅度降低,酶解48 h时分别下降了15.03%和13.96%,这说明水抽提液在稀酸预处理过程中产生了对酶水解有抑制作用的物质。因此,通过水抽提去除部分水抽提物可减少稀酸预处理过程中抑制物的产生,从而提高酶水解得率的能力。 相似文献
2.
采用微波辅助稀酸法对棉花秸秆进行水解糖化。探索了微波辐射温度、微波辐射时间、料液比及硫酸浓度对秸秆水解糖化效果的影响。结果表明,微波辅助棉花秸秆稀酸水解糖化的最佳糖化工艺条件为:微波辐射温度80℃,微波辐射时间50min,料液比1∶16g/mL,硫酸浓度3.0%。各影响因素对还原糖收率的影响顺序为:料液比微波辐射温度硫酸浓度微波辐射时间。在最佳糖化工艺条件下,还原糖收率为3.17%。 相似文献
3.
4.
以长期驯化选育得到的耐抑制物氧化葡萄糖酸杆菌Glucobacter oxydans NL71为催化菌株,对全细胞直接催化木质纤维(麦秆)稀酸预处理水解液产木糖酸的工艺进行研究。结果表明:未脱毒水解液对催化反应生产木糖酸具有抑制作用,且随浓度提高,抑制作用增强。提高细胞浓度和提高供氧能力可以有效抵抗麦杆稀水解液的抑制效应。在摇瓶体系中以2 g/L细胞接种量直接催化未经脱毒的麦秆稀酸水解浓缩液,当初始木糖质量浓度超过100 g/L时,细胞的催化性能受到严重抑制,木糖酸得率均低于50%;当细胞接种量提升至8 g/L时,木糖酸得率可以达到85.7%;在机械搅拌式通氧加压反应体系中,采用密封加氧技术对100 g/L木糖浓度的麦秸稀酸水解浓缩液全细胞催化24 h的细胞接种量8 g/L,木糖酸终质量浓度达到103.1 g/L,木糖酸得率可达到93.1%,产生速率为摇瓶体系的1.6倍。 相似文献
5.
6.
7.
8.
9.
稀酸水解菊芋制乙醇技术研究 总被引:1,自引:0,他引:1
考察了固液质量比、酸浓度、反应温度和反应时间4个条件对菊芋粉稀酸水解的总糖浓度和总糖转化率的影响。结果表明,菊芋稀酸水解的最优化条件为:固液比0.3,硫酸浓度3%,反应温度80℃,反应时间90 min。在此条件下水解菊芋,水解液中的总糖浓度为24.1%,总糖转化率为80.3%;水解液经过中和后,接入酵母菌发酵产乙醇,最终乙醇浓度可达到10.4%,乙醇得率为86.4%。 相似文献
10.
采用焙烧酸化法对凹凸棒土进行了改性,通过单因素实验对凹凸棒土的热改性条件进行了优化,且采用N2吸附-脱附、X射线衍射、扫描电镜等表征手段对其脱色机理进行了研究。结果表明,对玉米秸秆稀酸水解液的脱色效果最佳的凹凸棒土热改性条件:450℃焙烧2 h、酸浓度10%。酸化作用使凹土内粒间杂质胶结物和碳酸盐矿物分解,疏通内部孔道,H+与凹土结构内阳离子置换,增大比表面积,改善其表面特性;焙烧活化可除去不同状态的水,改变其结构,增大孔容和比表面积;两者结合处理使颗粒白土的吸附脱色能力提高。 相似文献
11.
12.
Rui Zhang Xuebin Lu Youshan Sun Xinying Wang Shuting Zhang 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2011,86(2):306-314
BACKGROUND: Because of its high cost, nitric acid has not been widely employed as the catalyst for hydrolysis of lignocellulosic biomass to obtain fermentable sugars. However, recently more and more research results have reported that nitric acid was more effective than other acids for the hydrolysis of lignocellulose. Therefore, it is necessary to find an optimum condition for nitric acid pretreatment and a means of reducing the cost. RESULTS: In this work, low concentrations of nitric acid and short reaction times were considered to optimize the pretreatment process. The kinetic parameters of models to predict the concentrations of xylose, glucose, arabinose, acetic acid and furfural in the hydrolysates were obtained. Applying the kinetic models, the optimum conditions were: 150 °C, 0.6% HNO3 and 1 min, which yielded a solution containing up to 22.01 g L?1 xylose, 1.91 g L?1 glucose, 2.90 g L?1 arabinose, 2.42 g L?1 acetic acid and 0.21 g L?1 furfural, which were consistent with the predicted values. The influence of temperature was also studied using the Arrhenius equation. CONCLUSIONS: A combination of experimental data and model analysis suggested that 96% xylose yield can be achieved by using low concentration nitric acid for a short reaction time, which could greatly reduce the pretreatment cost. Therefore, dilute nitric acid could be considered a good choice for the hydrolysis of corn stover. Copyright © 2010 Society of Chemical Industry 相似文献
13.
盐酸水解玉米秸秆木聚糖的动力学研究 总被引:1,自引:0,他引:1
对稀盐酸水解秸秆半纤维素生成木糖水解液过程进行动力学研究。分别测定了不同温度下,不同水解时间水解液中木糖质量浓度以及其降解产物糠醛的质量浓度。利用Saeman模型拟合木糖生成过程。实验表明,该模型能够较好地描述木糖生成过程以及其降解产物糠醛的产生过程。通过曲线拟和确定了不同水解温度下木糖的生成速率以及分解速率常数,同时利用Arrhenius方程确定木糖生成活化能Ea为116 kJ/mol。综合比较不同温度下水解液中的木糖以及糠醛质量浓度,确定使用质量分数为2%的稀盐酸于120℃下水解60 min为最佳水解条件。其水解液中木糖质量浓度可达20.99 g/L,糠醛质量浓度可维持在1.46 g/L以下。 相似文献
14.
15.
Although lots of basic studies , such as the hydrolysis and dissolution of lignocelluloses has made great progress in recent years , the hydrolysates containing complex mixture of pentose and hexose are very hard to be separated , and these process sometimes cause serious environmental problems in practical application of cellulose polymer degradation science.Herein , an efficient two-stage method for selective hydrolysis of lignocelluloses biomass is being developed in this paper by controlling of pH in an ionic liquid.The lignin-hemicelluloses matrix in corn stalk was hydrolyzed into xylose in 23.1% yield in the first stage ; and cellulose-rich residues from the first stage was by farther hydrolyzed to provide a glucose in 26.9%yield.Structure of the products were identified by 13 C NMR.It should be mentioned that , the ionic liquid which can be regenerated and reused throughout the process. The present work significantly opens an a new path to utilize each component of lignocellulose as raw materials producing biofuels , renewable energy and fine chemicals. 相似文献
16.
In this work, a selective two‐stage hydrolysis of lignocelluloses from corn stalk was developed through pH adjustment in 1‐n‐butyl‐3‐methylimidazolium chloride ([C4mim]Cl). In the first stage, the lignin–hemicelluloses matrix of corn stalk was disrupted and hydrolyzed in the ionic liquid at pH 4.5 and 90°C to obtain xylose with 23.1% yield. In the second stage, cellulose‐rich materials in solid residues were further hydrolyzed in the ionic liquid at pH 2–3 and 90°C to produce glucose with 26.9% yield, and pure lignin was also obtained. Structures of the hydrolysates were identified by 13C NMR and IR spectrum analysis, and the ionic liquid was recycled throughout the process. It is expected that the information provided here would be useful for the development of new methods to selectively produce monosaccharides from catalytic hydrolysis processes of biomass. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献
17.
以玉米秸秆为原料,通过碳化-磺化法制备了碳基固体酸(CSA),采用XRD、FTIR、XPS、SEM、阳离子交换与返滴定法等手段对其结构形貌进行表征,并考察了制备条件对固体酸表面活性基团含量与催化活性的影响。以NaOH/尿素冻融预处理后的纤维素为底物,研究了CSA催化纤维素水解糖化的效果与条件。结果表明:NaOH/尿素冻融预处理能够有效辅助固体酸催化纤维素水解,在350℃碳化2h、100℃磺化5h条件下制备的CSA催化性能最好,其酸量达3.94mmol/g,其中磺酸基、羧基、酚羟基含量分别为1.09mmol/g、1.36mmol/g、1.49mmol/g。在m(CSA)∶m(纤维素)=3∶1、水解温度200℃、水解时间为0.5h的条件下,纤维素水解还原糖得率与转化率分别为47.1%和63%。CSA循环利用3次催化活性下降不大。本研究可为废弃生物质原料制备的固体酸催化纤维素水解转化利用提供科学参考。 相似文献
18.
Khaled Belkacemi Safia Hamoudi 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2003,78(7):802-808
The enzymatic hydrolysis of hemicelluloses as a filtrate originating from aqueous/steam pretreated corn stalks was carried out using commercial enzyme systems of several activities composed of cellulases and β‐D ‐xylosidases from Aspergillus niger. The hydrolysis was conducted using free enzymes in aqueous substrate solution at a temperature of 30 °C and a pH of 5. Saccharification corresponding to 90% of potential simple sugar release was obtained after 10 h using 0.12 activity units (U) of Cellulases_1 complex per mg of dissolved solids present in the filtrate. Synergetic action of Cellulases_1 enzyme complex and β‐D ‐xylosidases proved to be effective for the hydrolysis of plant hemicelluloses. A lumped model based on the Michaelis–Menten approach successfully described the fate of the lumped variables describing the hydrolysis of the overall kinetics of corn stalk hemicelluloses. The maximum saccharification rate evolved with the cellulases concentration as . This overall and pseudokinetic tendency was comparable to those reported in the literature for more simple systems employing a defined substrate and a pure hydrolytic enzyme. The n‐value was found to be in the range of 0.1–0.9 depending on the substrate lump involved in the reaction system. Copyright © 2003 Society of Chemical Industry 相似文献
19.
Kinetic studies of xylan hydrolysis of corn stover in a dilute acid cycle spray flow-through reactor
Hongman ZHANG Qiang JIN Rui XU Lishi YAN Zengxiang LIN 《Frontiers of Chemical Science and Engineering》2011,5(2):252
Xylan of corn stover was pretreated with 1%, 2% and 3% (w/w) sulfuric acid at relatively low temperatures (90°C, 95°C and 100°C) in a dilute acid cycle spray flow-through reactor (DCF). The hydrolysis of xylan to its monomeric xylose was modeled by a series of first-order reactions. Both biphasic and Saeman hydrolysis models were applied to fit the experimental data. The results confirmed that the kinetic data of xylan hydrolysis fitted a first-order irreversible reaction model and the experimental data. The reaction rates of xylose monomer formation and degradation were sensitive to catalyst concentration and temperature. Higher catalyst concentration and lower reaction temperature result in high xylose yield. The activation energy for xylose formation and degradation were determined to be 112.9 and 101.0 kJ·mol-1, respectively. Over 90% theoretical xylose obtained from corn stover can be used to produce ethanol, xylitol and fumaric acid by fermentation. 相似文献
20.
以制备纤维乙醇得到的酶解玉米秸秆残渣为原料,采用碱性乙醇法提取木质素,然后用聚乙二醇/甘油溶液将木质素进行液化得到木质素基多元醇,并以此液化产物代替部分聚醚多元醇用于聚氨酯泡沫的合成。结果表明:碱性乙醇法得到的木质素提取率为93.5%,木质素质量分数达到94.1%;在PEG-400/丙三醇液化体系中,木质素液化率高达99.5%,液化产物羟值为360 mg KOH/g;在聚氨酯合成中,木质素液化溶液对聚醚多元醇的替代量可以达质量分数47%,所得聚氨酯泡沫产品的芯密度和压缩强度分别为48.6 kg/m3和212 k Pa,满足工业聚氨酯硬泡的国家标准。 相似文献