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金属离子助催化稀酸水解纤维素工艺的研究 总被引:1,自引:0,他引:1
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%。 相似文献
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Hadi Amirkhani Umer Rashid Shanti Faridah Salleh A. B. Dayang Radhiah Syafiie Syam 《Chemical Engineering Communications》2013,200(9):1235-1244
Oil palm frond (OPF) fiber, a lignocellulosic waste from the palm oil industry, contains high cellulose and hemicellulose content, thus it is a potential feedstock for simple sugars production. This paper describes the two-stage hydrolysis process focusing on the use of low-temperature dilute acid hydrolysis to convert the hemicellulose in OPF fiber to simple sugars (xylose, arabinose, and glucose). The objective of the present study was to evaluate the effect of operating conditions of dilute sulfuric acid hydrolysis undertaken in a 1 L self-built batch reactor on xylose production from OPF fiber. The reaction conditions were temperatures (100–140°C), acid concentrations (2–6%), and reaction times (30–240 min). The mass ratio of solid/liquid was kept at 1:30. Analysis of the three main sugars glucose, xylose, and arabinose were determined using high-pressure liquid chromatography. The optimum reaction temperature, reaction time, and acid concentration were found to be 120°C, 120 min, and 2% acid, respectively. Based on the potential amount of xylose (10.8 mg/mL), 94% conversion (10.15 mg/mL) was obtained under the optimum conditions with small amount of furfural (0.016 mg/mL). To enhance the effectiveness of dilute acid hydrolysis, the hydrolysis of OPF fiber was also performed using ultrasonic-pretreated OPF fiber. The effects of ultrasonic parameters power (40–80%) and ultrasonication times (20–60 min) were determined on sugar yields under optimum hydrolysis conditions (2% acid sulfuric, 120°C and 120 min). However, the use of ultrasonication was found to have detrimental effect on the yield of simple sugars due to the 10-fold increase in the formation of furfural. 相似文献
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Klaus Garves 《木材化学与工艺学杂志》2013,33(1):121-134
Abstract Cellulose is degraded by alcohols and strong acid-catalysts at 180°C to 200°C within minutes. Alkylglucosides, 5-alkoxyrnethylfurfurals, and alkyl levulinates plus alkyl formates are formed in consecutive reactions, accompanied by some humic residue. The scope of the reaction was explored by using C1-, C2-, C3-, and C4-alcanols and by combining various lignocellulosic substrates with methanol. Effects of catalysts and co-solvents were tested, resulting in more selective reactions and suppressing dialkylether formation of the solvent. Yields of 46% methyl levulinate, 44% ethyl levulinate, and 37% n-propyl levulinate (based on theory) from cellulose point to the preparative value of the reactions. 相似文献
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《纤维素科学与技术》2015,(2):19-26
研究了取代基对纤维素水解动力学的影响,纤维素酸性水解速率的大小直接决定纤维素材料的可用性以及纤维素转化成糖的效率,纤维素衍生物由于其特有的化学非均相性,水解动力学很少有人研究。本文量化了取代基效应、p H、温度对纤维素衍生物水解速率的影响;活性红120取代的纤维素二糖酸性水解反应速率为5.0×10-3 h-1,是未取代双糖速率的190倍,反应活化能较未取代的低10 k J/mol,并且发现被取代的纤维素二糖对质子更加敏感;最终基于反应的非均相性,建立了一个包含多种因素的水解动力学模型。这个模型对今后研究取代基催化纤维素水解的机理提供了帮助。 相似文献
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以玉米芯为底物,采用间歇反应釜,在固液比为0.1 g/mL,一定硫酸浓度(质量分数为0.1%~0.9%)和温度(130~170℃)下反应,建立酸水解动力学模型,通过非线性回归拟合获得模型参数。结果表明:较低温度和硫酸浓度可增大五糖碳收率和玉米芯中六碳糖保留率。合适的反应条件为130℃,H2SO4的质量分数为0.1%,反应82 min时,溶液中五碳糖浓度为36.2 g/L,五糖碳收率为90.7%,玉米芯中戊聚糖水解率为97.6%,六碳糖保留率为96.9%。 相似文献
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Although many previous studies have been carried on the enzymatic hydrolysis of corn stover after pretreatment with dilute sulfuric acid, this paper emphasizes the use of different conditions to attain the highest yields of two sugars, xylose and glucose, from both stages. The pretreatment was performed at a range of sulfuric acid concentrations of 2, 4 and 6 % at 80, 100 and 120 °C. Up to 77 % xylose yield was obtained while the glucose yield was only 8.4 %. The corresponding solid phase was hydrolyzed by cellulase and the influences of five factors and their interactions on enzyme hydrolysis were evaluated by response surface methodology based on one‐factor‐at‐a‐time experiments. The optimal levels for each variable to obtain the highest reducing sugar yield were as follows: enzyme concentration of 22 FPU/g substrate, substrate concentration of 77 g/L, temperature of 49 °C, pH 4.8 and reaction time of 38 h. A reducing sugar yield of 42.11 g/100 g substrate was achieved, which was consistent with the predicted value of 42.13 g/100 g substrate. Compared with the one‐factor‐at‐a‐time experiments, there was a 9.4 % increase in reducing sugar yield when the enzyme concentration was decreased to 3 FPU/g substrate, the substrate concentration increased to 17 g/L and the reaction time dropped to 22 h. The total sugar released from the two stages was 62.81 g/100 g substrate. 相似文献
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With dilute hydrochloric acid as catalyst and promoted by ferrous chloride, hydrolysis of waste sawdust to produce monosaccharides was conducted by using an one-step method in a batch-wise operation reactor. Based on the model of first order consecutive irreversible reactions, the kinetics equation incorporating the term of catalyst concentration was obtained that is suitable for describing the hydrolysis of sawdust. Activation energies were calculated for hydrolysis of sawdust and decomposition of monosaccharides. 相似文献
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采用稀HCl和HNO3在酸质量分数为1.0%、2.5%和4.0%,反应时间10、30、50、90和120 min,温度90和150 ℃条件下,对玉米芯水解产木糖进行研究。通过动力学模型数据预测木糖浓度,并采用响应曲面优化各个温度下的水解条件。优化得到的最适宜水解条件为温度150 ℃,预处理时间10 min,酸质量分数为1.0%;对应HNO.3.得到的木糖浓度为56.77 g/L,产率96.31%;HCl木糖浓度为45.38 g/L,产率76.99%。动力学结果成功预测了反应条件下的木糖浓度。通过对比得出HNO.3.对玉米芯的水解效果要优于HCl。 相似文献
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主要研究了微晶纤维素在甲酸体系中的水解动力学。探讨了甲酸体系中盐酸质量分数、微晶纤维素加入量、反应温度、反应时间对微晶纤维素水解的影响。分析了在该体系中葡萄糖的降解情况,结果表明葡萄糖的降解反应与纤维素的水解反应相比是个快速反应。微晶纤维素在甲酸体系中的水解速率55℃时为6.34×10-3 h-1,65℃时为2.94×10-2 h-1,75℃时为6.84×10-2 h-1。葡萄糖的降解速率55℃时为0.01h-1, 65℃时为0.14h-1, 75℃时为0.34 h-1。微晶纤维素水解的表观活化能为105.61kJ/mol,葡萄糖的降解表观活化能131.37kJ/mol。 相似文献
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以亚临界H2O-CO2二元体系为反应介质,采用高效液相色谱法对纤维素制备乙酰丙酸的产物进行分析,探讨了亚临界水解纤维素反应制备乙酰丙酸的反应机理,并建立了其反应动力学方程.结果表明,亚临界水解纤维素反应制备乙酰丙酸的反应为一级反应,其表观活化能为141.52 kJ/mol,指前因子为3.73×1011 min-1. 相似文献
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采用纤维素衍生碳、活性炭和介孔碳材料CMK-3为不同碳源前驱体,在不同磺酸化条件下制备磺酸化碳材料负载Ru的双功能催化剂,并用FTIR光谱、XRD、元素分析、热重分析、N2物理吸附 脱附进行了表征,考察了其对纤维素加氢反应的催化活性。结果表明:相比于纤维素衍生化碳,活性炭和介孔碳CMK-3为碳源经过磺酸化后制备的催化剂具有较强的结合-SO3H的能力和较高的催化活性,对多元醇具有良好的选择性,170 ℃下反应10 h六元醇的收率可高达84.0%。在循环使用时,磺酸化活性炭负载Ru催化剂催化活性有所降低,但可以保持对多元醇的选择性;而磺酸化介孔碳负载Ru催化剂存在少量S流失,转化率基本不变,但产物的选择性有所降低。 相似文献
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Degradation Kinetics of Xylose and Glucose in Hydrolysate Containing Dilute Sulfuric Acid 总被引:3,自引:0,他引:3
In preparation of fuel alcohol from biomass as feedstock, hydrolysis with dilute acid as catalyst is one way to produce fermentable saccharide, xylose and glucose. However, the acid is also the catalyst in degradation of xylose and glucose and the yield of sacchride is dependent on the kinetic behaviors of saccharide. The degradation kinetics of xylose and glucose in the hydrolysate was investigated under the conventional process conditions of hydrogen ion concentration from 0.05 to 0.2 mol/L and temperature from 150 to 200℃. With a numerical calculation method, the kinetic parameters were estimated, and the activation energy of xylose and glucose in the degradation reaction was obtained. The kinetic equations correlating the effect of hydrogen ion concentration on the rate constants of degradation reaction were established. Comparison between the calculated results from the equations and experimental ones proved that the established kinetic model could satisfactorily predict the degradation behavior of xylose and glucose in the acidic hydrolysate. 相似文献
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稀硫酸催化水解稻草秸秆半纤维素的研究 总被引:1,自引:0,他引:1
对稀硫酸催化水解稻草秸秆半纤维素进行了研究.考察了固液比、稀硫酸质量分数、反应温度、反应时间对半纤维素水解的影响.采用正交实验法,以总还原糖含量为考察指标,对实验结果进行直观和方差分析,探讨稀硫酸催化水解半纤维素的最优反应条件.结果表明,稀硫酸催化水解稻草秸秆半纤维素以固液比(质量体积比)1:10、稀硫酸质量分数25%、反应温度95℃、反应3h为最优条件,在此条件下,10g稻草秸秆粉末水解得到总还原糖2.704g,总还原糖收率达94.9%. 相似文献
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与固相缩聚工业生产用常规粒径聚酯相比,粉状聚酯的传质和反应均可得到增强.实验研究了不同粒径粉状聚酯(0.2~0.8 mm)在氮气氛围中的固相增黏规律,并采用模型方法对缩聚反应与降解行为进行了分析.结果表明粉状聚酯的固相缩聚反应是缩聚与降解的竞争过程,反应初期缩聚反应占主导地位,特性黏度随反应不断增加,后期降解反应占主导... 相似文献