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1.
分别将木粉、纤维素和木质素在乙二醇中进行热化学液化.研究结果表明木粉中纤维素的非结晶区、木质素和半纤维素首先被液化,而纤维素的结晶区较慢被液化,到液化反应中期基本降解完全,液化产率高于97％.利用在线红外光谱仪跟踪检测了整个液化反应过程,结合GC-MS结果发现:乙二醇在反应过程中脱水生成了二甘醇和三甘醇.在液化反应中,纤维素的糖苷键断裂后生成葡萄糖苷结构,随后葡萄糖苷中的吡喃环也被打开,生成的活性中间体相互反应或与乙二醇反应生成了如3-(2-甲基-[1,3]-二氧戊环-2-基)-丙酸乙酯、乙酰丙酸丁酯等酯类;木质素的苯丙烷结构主要降解为苯酚、2,6-甲氧基苯酚等芳香族衍生物,因此木粉液化产物是聚醚/酯混合多元醇. 相似文献
2.
麦草催化热化学液化产物的组成分析 总被引：10，自引：0，他引：10
麦草和纤维素、木质素等原料分别在乙二醇反应介质中，以浓硫酸/苯酚为催化剂进行液化反应。分析了液化产物组成，探讨了液化过程中各成分的液化情况。实验表明：麦草中要木质素组分在酸性条件下酚化降解，生成一系列单体、二聚体和多聚体，纤维素则最终降解生成乙二醇缩-2-羰基戊酸乙酯。元素分析显示，麦草、碱木质素液化残渣主要成分为灰分，且灰分中主要成分为SiO2。残渣中碳的含量比原料有显著增加，显示原料在反应条件下发生炭化。测定了产物的相对分子质量分布，发现随着反应的进行，降解和缩合同时发生，从而导致相对分子质量分布变宽。 相似文献
3.
《林产化学与工业》2017,(2)
以乙二醇为溶剂,在1-磺酸丁基-3-甲基咪唑硫酸氢盐([C_4H_8SO_3 Hmim]HSO_4)酸性离子液体催化下,进行桉木屑的液化反应。考察了反应温度、反应时间、催化剂用量对液化率以及产物分布的影响,并对液化产物进行了表征。结果表明:在最优液化条件10 g桉木屑,60 g乙二醇,[C_4H_8SO_3 Hmim]HSO_4用量为10 mmol,液化温度为160℃,液化时间150 min下,桉木屑的液化率最高可达96.41%。在离子液体催化下,桉木屑中的半纤维素和木质素快速液化;液化残渣的主要成分为未降解的结晶区纤维素(结晶度75%左右),液化产物水不溶性级分主要为木质素的降解产物,液化产物水溶性级分主要由纤维素的降解产物乙酰丙酸以及乙酰丙酸甲酯组成。 相似文献
4.
针对传统木材苯酚液化技术中存在的反应时间长、产物黏度高和反应活性降低等问题，采用微波加热方式，将杨木木粉在酸化苯酚溶剂中进行快速解聚反应。结果表明，微波加热条件下杨木苯酚液化的适宜条件为：木粉含水率30%～40%，液化时间15 min，苯酚与木粉的比例(P/W)2.5，木粉粒径0.18～0.25 mm，在此条件下木材液化率达到87%。微波加热的木材苯酚液化速率比传统油浴加热提高至少6倍。木材被降解为醇类、酸类、醚类、醛类和酚类等低分子质量物质，液化产物黏度显著降低，仅为3015 mPa·s，且与甲醛的反应活性较高，100 g液化产物反应消耗的甲醛达2.1 mol。微波加热与传统加热下的木材苯酚液化反应历程不尽相同，主要表现在纤维素和半纤维素降解为单糖后，单糖可进一步断裂为2，3－丁二醇、1，2－丙二醇、乙二醇和乙二醛等物质，这些物质相互之间可以发生脱水、羟醛缩合等反应进一步生成 2－乙氧基－丙烷，1，1－二乙氧基－乙烷、二异丙基缩甲醛和12－冠醚－4。 相似文献
5.
酸催化下苯酚液化木材的制备与表征 总被引：19，自引：3，他引：19
在硫酸作用下用苯酚对人工林杨木和杉木进行液化,考察反应时间、反应温度等对液化反应的影响,并对液化产物进行表征分析.结果表明:1)在硫酸催化下,杨木和杉木被苯酚液化的历程相似,但残渣含量稍有不同.酸性催化剂不仅对纤维素和半纤维素起作用,对木质素也起作用.2)反应温度比反应时间对液化效率的影响大,二者均能影响液化产物的分子量和分子量分布.通常杉木液化产物的重均分子量高于杨木.3)液化过程中,木质素和半纤维素首先被液化,最后是纤维素.木材组分的分解、酚化和再缩聚反应主宰整个液化动力学过程及液化产物的结构特征. 相似文献
6.
7.
为了确定蜜环菌对榛子木材木质部和树皮部分的降解作用,以及对其成分的影响,本文对受蜜环菌降解不同时间的榛子木材的红外光谱进行研究。方法:选择蜜环菌作为侵染榛子木材的腐朽菌,以健康榛子木材和受蜜环菌腐朽40d、80d以及腐朽1年的榛子木材为研究材料,利用傅里叶变换红外光谱分析仪(FTIR)测定其红外光谱图。根据图谱中木质素、综纤维素及草酸钙官能团谱峰位置和谱峰相对吸收强度的振动变化情况,分析被蜜环菌腐朽后的榛子木材成分的变化情况。结果表明:榛子木材树皮部分和木质部中主要成分为木质素、综纤维素和一水草酸钙结晶(COM)。这3种成分均能被蜜环菌降解,并随着降解时间的改变,榛子木材成分发生不同程度的变化。其中,草酸钙可以被蜜环菌降解至含量很低,并能够在综纤维素降解时,再大量生成;另外,木质素的相关吸收峰,仅在受蜜环菌降解1年的榛子木材树皮部分发生变化,说明木质素很难被降解。 相似文献
8.
木质纤维素及其组分转化木材胶粘剂的发展趋势 总被引：1，自引：0，他引：1
木质素是造纸工业废液中的主要成分。其具有和酚醛树脂相似的结构, 因此可以部分替代苯酚用于酚醛树脂的生产。但是由于木质素化学结构复杂, 具有化学反应活性的位点少、反应官能团所收到的空间位阻大, 一般添加量不超过10%~20%。有机溶剂法制浆分离的木质素分子量大, 纯度高, 酚醛树脂允许的添加量可达20%~30%, 但是要求提高固化温度、延长固化时间来克服木质素反应活性低的限制。对木质素进行化学改性如羟甲基化、酚解、醇解、还原等, 可以降低分子量, 增加活性基团如酚羟基的含量、并使苯环上更多的活性位点暴露出来, 从而提高木质素的化学反应活性。酚醛树脂经过改性木质素的允许的添加量可达30%~40%。部分木质素含量高的木质纤维素类原料如核桃壳粉等, 经过研磨和化学活化处理后可以直接添加到酚醛树脂中, 部分替代苯酚而不对胶接性能产生影响。环碳酸酯类和多元醇混合物被用来作为全新的液化剂来把木质纤维素快速液化为有用的化学原料。所得到的液化产物具有较高的反应活性, 是今后利用木质纤维素开发绿色木材胶粘剂的一条可资利用的途径。 相似文献
9.
《林产化学与工业》2017,(6)
将三大组分的模型化合物微晶纤维素、木聚糖和木质素进行不同配比得到合成生物质,对不同配比的合成生物质样品进行热重(TG)分析,研究了其溶剂辅助热解液化行为,并得出三大组分在溶剂辅助热解液化过程中的协同作用。研究发现:温度低于350℃时,半纤维素对纤维素的降解有一定的促进作用;而高于350℃时,则有明显的抑制作用;半纤维素和纤维素均对木质素的降解起到抑制作用。采用极端顶点法选取典型配比的合成生物质,运用热裂解-色谱-质谱联用技术(Py-GC/MS)探究了合成生物质的溶剂辅助热解液化产物分布,得出了生物质各组分对溶剂辅助热解液化产物分布的影响。结果表明:合成生物质中的木质素含量较高会促进酸类物质的生成,纤维素和半纤维素的溶剂辅助热解液化产物对木质素溶剂辅助热解生成酚类化合物有一定的抑制作用;对于酯类化合物来说,合成生物质溶剂辅助热解液化都生成了较多的酯类物质,生物质三组分不同的配比促进了酯类化合物的生成。 相似文献
10.
以小麦秸秆为原料,浓硫酸为催化剂,乙醇为溶剂进行液化实验,分析了液化产物的组成,考察了不同条件对目标产物乙酰丙酸乙酯(EL)得率及液化率的影响。结果表明:在浓硫酸用量10%、反应温度190℃、反应时间60 min,液固比为18∶1(g∶g)条件下,小麦秸秆的液化效果较好,液化率为75%,此时EL的得率为18.11%;经红外光谱分析可知秸秆在反应过程中发生降解;液体产物中包含醛、酮、酯、酚、酸类等多种含氧化合物,纤维素降解生成葡萄糖、葡萄糖苷、乙氧基甲基糠醛等中间产物,并最终转化为乙酰丙酸乙酯。 相似文献
11.
Characterization of the products resulting from ethylene glycol liquefaction of cellulose 总被引：9，自引：0，他引：9
The composition of liquefied cellulose in the presence of ethylene glycol (EG) was studied. The liquefied products were fractionated and analyzed with highperformance liquid chromatography and nuclear magnetic resonance. EG-glucosides were detected as the only saccharides and 2-hydroxyethyl levulinate as the highly decomposed compound derived from cellulose. Quantitative analysis of the EG-glucosides and levulinic acid that comes from the levulinate shows the presence of the following mechanism in the EG-liquefaction of cellulose. First, cellulose is degraded and produces considerable amounts of EG-glucosides during the early stage of liquefaction. Then, when liquefaction is prolonged, the glucosides are decomposed, leading to a large quantity of levulinates. 相似文献
12.
Masahiko Kobayashi Toshiyuki Asano Mikio Kajiyama Bunichiro Tomita 《Journal of Wood Science》2005,51(4):348-356
The effects of ozone treatment were investigated to improve the process of liquefaction of wood with polyhydric alcohol solvents. The liquefied wood having a high wood to polyhydric alcohol ratio (W/P ratio) could be prepared by using the wood treated with ozone in the liquid phase. The liquefied wood with a W/P ratio of 2 : 1 had enough fluidity to act as a raw material for chemical products. To get some information about the effects of ozone treatment toward the wood components, cellulose powder and steamed lignin were treated with ozone and liquefied. In particular, ozone treatment in the liquid phase was found to be effective for wood and cellulose powder. On the other hand, steamed lignin self-condensed during liquefaction after treatment with ozone in the liquid phase. Thus, ozone treatment provided lignin with reactive functional groups, and caused the subsequent condensation reaction. Although lignin was converted to a more condensable structure by ozone treatment, the condensation reaction was found to be suppressed for wood during its liquefaction. The wood liquefied products displayed good solubilities in N,N-dimethyl formamide (DMF) even after treatments of long duration. It was suggested that one of the main effects of ozone treatment toward wood was the decomposition of cellulose.Part of this report was presented at the 53rd Annual Meeting of the Japan Wood Research Society, Fukuoka, April 2003 相似文献
13.
Liquefactions of cellulose powder, steamed lignin, alkali lignin, and their mixtures were carried out to analyze the reaction process of wood using polyhydric alcohol. The liquefaction of wood proceeded immediately and wood components were converted to N,N-dimethylformamide (DMF)-soluble components. After that, the condensation reaction occurred with increasing reaction time. However, none of cellulose powder, steamed lignin, and alkali lignin condensed by themselves during their liquefaction. The mixture of cellulose and lignin was also liquefied, and condensed after a long reaction time. The results of analysis showed that the behavior of the mixture resembled that of wood with respect to molecular weight distribution and the main functional groups. Lignin was converted to DMF-soluble compounds in the initial stage of wood liquefaction, followed by cellulose gradually being converted into soluble compounds. After that, condensation reactions took place among some parts of depolymerized and degraded compounds from cellulose and lignin, and were converted into DMF-insoluble compounds. It was concluded that the rate-determining step of wood liquefaction was the depolymerization of cellulose. Furthermore, it was suggested that the condensation reaction was due to the mutual reaction among depolymerized cellulose and degraded aromatic derivatives from lignin or due to the nucleophilic displacement reaction of cellulose by phenoxide ion.Part of this report was presented at the 52nd Annual Meeting of the Japan Wood Research Society, Gifu, April 2002 相似文献
14.
IKEDA Atsushi 《中国林业科技(英文版)》2003,(2)
By means of gel permeation chromatography analysis, the molecular weight of liquefied wood under different reaction conditions was investigated to trace the change in the structural characteristics of the liquefied wood. The insoluble residues were analyzed by Fourier transform infrared to investigate the liquefaction order of three main wood components. The results indicate that both reaction temperature and reaction time could affect the molecular characteristics of the liquefied wood obtained. The molecular weight of liquefied Chinese Fir wood is higher than that of liquefied Poplar wood under most of reaction conditions. During wood liquefaction, lignin is liquefied firstly. Hemicellulose is liquefied in the middle stage and cellulose is the most difficult to be liquefied. 相似文献
15.
The liquefied product of Salix psammophila wood was separated by thin-layer chromatography (TLC) and column chro-matography, and its structure was identified by nuclear magnetic resonance (NMR) spectra in our study. The separation result indi-cates that the sample of liquefied S. psammophila contained at least two categories of components. The structure of the main compo-nents was guaiacyl C-1, C-2 of the hydroxyphenyl propane, i.e., the aromatic nucleus protons of lignin. Degradation and polycon-densation reactions occurred when the S. psammophila wood was liquefied in phenol. Polycondensation reactions occurred among the depolymerization products from cellulose, the aromatic depolymerization products from lignin and the products of the displace-ment reactions between phenoxide ion and cellulose. 相似文献
16.
Separation of liquefied product of Salix psammophila by column chromatography and structure analysis of its components 总被引：2，自引：1，他引：1
The liquefied product of Salixpsammophila wood was separated by thin-layer chromatography （TLC） and column chromatography, and its structure was identified by nuclear magnetic resonance （NMR） spectra in our study. The separation result indicates that the sample of liquefied S. psammophila contained at least two categories of components. The structure of the main components was guaiacyl C-1, C-2 of the hydroxyphenyl propane, i.e., the aromatic nucleus protons of lignin. Degradation and polycondensation reactions occurred when the S. psammophila wood was liquefied in phenol. Polycondensation reactions occurred among the depolymerization products from cellulose, the aromatic depolymerization products from lignin and the products of the displacement reactions between phenoxide ion and cellulose. 相似文献
17.
Liquefied wood is a naturally based product which has the potential to be used as an adhesive. The bonding of wood with liquefied wood requires a high enough temperature to cure the liquid polymers and achieve bond strength. Dielectric analysis, rheometry and differential scanning calorimetry were used to analyse the curing process of low solvent liquefied wood. For the liquefaction, ethylene glycol was used as a solvent and sulphuric acid was used as a catalyst. The dielectric analysis was used for in situ measurements of the curing of liquefied wood during the bonding of wood. It was found that curing started after a temperature of 100 °C had been reached in the bond. This is correlated with the water evaporation and the diffusion of water and ethylene glycol from the liquefied wood into the wood substrate. Rheological measurements proved the influence of the substrate on the curing of the liquefied wood during bonding. Differential scanning calorimetry showed that the curing of liquefied wood occurs in two parts: first, the initial elimination of water and ethylene glycol from the liquefied wood, and then the chemical reaction of the liquefied wood at higher temperatures. 相似文献
18.
【目的】将微波加热与甘油利用相结合的综合炼制工艺用于木质纤维素生物质预处理,探索其在燃料乙醇制备中的可行性,为实现经济可行、经济有效的木质纤维素生物质酶解预处理技术和生物燃料生产提供基础信息。【方法】以银腺杨、日本落叶松、刚竹和柳枝稷为试验材料,采用微波液化法对其进行液化处理,将液化产物分为纤维素、半纤维素和木质素组分,并对纤维素纤维组分进行综合表征。【结果】化学分析结果表明,纤维素纤维具有较高的葡聚糖含量;红外光谱显示,木质素和半纤维素的信号逐渐减弱,说明半纤维素和木质素经液化处理后有效脱除;XRD分析结果表明,纤维素纤维结晶度高、表面积大。【结论】相比原木质纤维素生物质,银腺杨、日本落叶松、刚竹和柳枝稷4种原材料纤维素纤维的酶解糖化效率均有不同程度提升(最高酶解转化率可达70%),液化固体产物--纤维素纤维在制备燃料乙醇中具有广阔的潜力和前景。 相似文献
19.
Liquefaction and product identification of main chemical compositions of wood in phenol 总被引：3，自引：0，他引：3
Zhang Qiu-hui Zhao Guang-jie Jie Shu-jun 《中国林学(英文版)》2005,7(2):31-37
To clarify liquefaction ratios and their construction variations of the main chemical compositions of wood in phenol using phosphoric acid as a catalyst, the chemical ingredients of wood such as holocellulose, cellulose and lignin, were measured and extracted according to GB methods. With Fourier transform infrared （FTIR）, the product identification of reactant before and after liquefaction in phenol was investigated. The molecular weights and their distributions of the liquefaction results （acetone soluble parts） were studied by gel permeation chromatography （GPC）. Results show that the molecular weights and their distributions of poplar and Chinese fir are almost the same. In poplar, the distribution of cellulose is the largest, and that ofholocellulose the smallest after liquefaction. For Chinese fir, the distribution of holocellulose is the largest, and that of cellulose the smallest. After liquefaction of poplar cellulose, the change bands of FTIR spectrum observed below 1 600 cm^-1, can be attributed to new substitute groups. The same is true for poplar lignin. For Chinese fir, the spectra of liquefaction results of all chemical compositions differ from that of wood meal. This reveals the more activity groups were produced because of the reactions between Chinese fir and phenol. The research shows that the liquefaction ratios of poplar decrease in the following order： holocellulose 〉 lignin 〉 cellulose, and those of Chinese fir in the order： lignin 〉 cellulose 〉 holocellulose. 相似文献
20.
Hisashi Miyafuji Kenji Miyata Shiro Saka Fumio Ueda Midori Mori 《Journal of Wood Science》2009,55(3):215-219
Reaction of Japanese beech (Fagus crenata) in an ionic liquid, 1-ethyl-3-methylimidazolium chloride ([C2mim][Cl]), which can dissolve cellulose, was investigated.
Although both lignin and polysaccharides such as cellulose and hemicelluloses can be liquefied at a treatment temperature
of around 100°C, the liquefaction of polysaccharides mainly occurs at the beginning of the treatment with [C2mim][Cl]. Cellulose
crystallinity in the wood was gradually broken down as the treatment continued. The solubilized polymers were depolymerized
to low molecular weight compounds. The results indicate that [C2mim][Cl] is an effective solvent and reagent for the liquefaction
of wood components and subsequent depolymerization of them.
Part of this report was presented at the 58th Annual Meeting of the Japan Wood Research Society, Tsukuba, April 2008 相似文献