纤维素典型热解产物生成机理研究进展

利用生物质热解来生产液体燃料和高价值化学品受到广泛的关注,对生物质组分热解机理的研究有助于对生物质热解规律的理解和对热解过程的调控。对纤维素热解及其典型热解产物如脱水糖类、呋喃类以及小分子化合物等的生成机理进行综述,并指出后续的研究应该选用合适的模化物;为实现纤维素的高值化利用,还应对纤维素在不同类型催化剂作用下的催化热解机理进行研究。     

木材液化技术的研究进展

综述了近30年来国内外木材液化技术的研究进展,简介了以酸或碱为催化剂、无催化剂和超临界萃取等木材液化的主要方法,木材液化技术对充分利用自然界中可再生资源、降低环境污染具有重要的意义.     

硬木纤维素蒸汽闪爆处理机理的研究

研究了硬木纤维素在蒸汽闪爆改性过程中的各种状态及蒸汽闪爆对硬木纤维素超分子结构的影响。用SEM、X-射线衍射、FT-IR分析及对聚合度Pv、溶解度Sa的研究结果表明,蒸汽闪爆改性后硬木纤维素的结晶度Xc(X)和微晶尺寸L002有所增加,但其超分子结构遭到破坏,游离羟基和可及度有所增加,尤其是纤维素内部氢键的断裂与纤维素的Sa有十分密切的关系。     

农林剩余物的液化及液化产物利用研究进展

从液化方法、液化机理及液化产物利用等方面对农林剩余物的研究进展进行了综述,指出存在的主要问题并提出了合理建议,为农林剩余物的高值化应用提供了参考。     

亚/超临界乙醇条件下杨木屑与甘油共液化研究

以60～80目的杨木屑为原料,甘油为液化剂,酸为催化剂,基于超临界乙醇条件下对杨木屑进行液化制备生物重油。实验结果表明:以2.5%硫酸为催化剂,在甘油/乙醇/木屑质量比为5∶10∶2条件下,250℃反应1 h,木屑的转化率可达98%。此液化油含水量为3.04%(wt),运动黏度为524 mm2/s,酸值为2.1 mg KOH/g,羟值为846 mg KOH/g。对液化油进行IR、GPC和GC-MS分析的结果显示,液化油含有大量的羟基物质,平均相对分子质量为811,并且含有4-羰基戊酸丁酯、三乙基甘油醚等聚酯/聚醚类多元醇。     

纤维素快速热解生成左旋葡聚糖的机理研究进展

左旋葡聚糖（LG）是纤维素中温快速热解最重要的产物,其生成机理获得了广泛的关注。本文首先总结了国内外不同学者提出的LG生成机理,将其按照反应类型分为4类,即糖苷键均裂反应、糖苷键异裂反应、生成葡萄糖中间体反应以及协同反应,并指出了实验研究在确定反应机理方面的不足。随后总结了近年来一些学者采用密度泛函理论对LG生成机理的研究,具体比较了研究内容和结果,指出了现有研究的不足。最后提出了今后的研究方向以确定LG的生成途径。     

Effect of the Loosening of Wood Texture on the Mercerization of Cellulose in Wood

When wood was treated with 23% aqueous sodium hydroxide followed by washing with water and drying, no lattice conversion of cellulose was observed under the experimental conditions employed. On the other hand, wood subjected to a pretreatment that results in the loosening of its morphological texture, upon mercerization, showed a varying degree of lattice conversion. The explosion process and the TFA (trifluoroacetic acid) treatment were used to achieve the loosening of wood texture. The lattice conversion of cellulose was studied by X-ray diffractograms. The extent of lattice conversion was found to depend on the conditions of the pretreatment used to achieve the loosening of wood texture. The extent of lattice conversion increased with an increase in the explosion temperature and the time at temperature, within the range of these experiments. Increased duration of TFA pretreatment, at a particular temperature, resulted in a higher degree of lattice conversion. These observed facts have been ascribed to the extent of loosening of the morphological texture of wood, which allows comparatively free swelling of cellulose in alkali.     

棉浆和木浆掺混纺醋酸纤维素纤维结构与性能的分析

对棉浆和木浆三种掺混纺比例(棉浆与木浆的掺混纺比例为0∶100,50∶50,100∶0)的醋酸纤维素纤维的结构与性能进行了测试分析。采用光学显微镜观察、纤维图形分析软件计算、X射线衍射和强伸性能测试,对比分析了三种掺混纺比例纤维的截面形态、结晶度、取向度、断裂伸长率、断裂强度以及初始模量,为棉浆与木浆掺混纺醋酸纤维素纤维的广泛应用提供了理论依据。实验结果表明:三种掺混纺比例纤维的截面形态指标无显著差异,内部晶体基本结构相同,随着棉浆与木浆掺混纺比例的增加,结晶度、取向度以及强伸性能呈现出略微增大的趋势。     

宝浪油田地层结垢机理研究

对宝浪油田地层结垢倾向进行了理论分析,对宝浪油田地层结垢机理进行了静态试验研究.     

Studies on Formation and Recrystallization of Intermediate Reaction Products in the System Magnesia-Silica-Water

Mixtures of magnesia and silicic acid ranging in composition from 0.5 to 2.0 M/S were treated hydrothermally at temperatures of 75° to 350°C. for various periods of time. The reaction solids were examined by differential thermal analysis, X ray, and electron microscopy and analyzed chemically. The intermediate products of reaction ranging in composition between that of talc (0.75 M/S) and chrysotile (1.5 M/S) comprised a continuous series of cryptocrystalline needle-like crystaIs matted tightly together and showing the same X-ray pattern. The initial reaction product of the 0.75 to 1.50 M/S raw mixtures was a cryptocrystalline solid having a 1.5 M/S ratio. This phase subsequently reacted with the residual silica, so long as any was available, to form a solid having the composition of the raw mix, but only at relatively moderate temperatures(100°to175°C.). As the temperature was increased the crystals of the 0.75 and 1.50 M/S compositions increased in size, but all remained submicroscopic. The compositions intermediate between 0.75 and 1.5 M/S crystallized as mixtures of talc and chrysotilelike products. The chrysotilelike product appeared as minute needles which did not possess any apparent flexibility.     

木材液化及其在高分子材料中的应用

木材通过液化可转化为具有反应活性的液态产物,进一步反应可以制备胶粘剂、聚氨酯材料等新型高分子材料。文章从方法、机理以及其产物在制备高分子材料等方面对木材液化的研究进展进行了评述。     

Lattice Conversion of Cellulose in Wood

When peracetylated wood, prepared in an acetic anhydride-pyridine medium, was saponified and recrystallized, almost no conversion of cellulose I to cellulose II took place. Neither was conversion detected, when thirteen species of wood, differing in density from 0.17 to 0.71, as well as in lignin content from 18.1 to 38.8 %, were treated with 17.5 % aqueous NaOH, followed by recrystallization. The corresponding treatments for cellulose triacetate or cellulose resulted in complete conversion to cellulose II. Partial delignification of wood preceding the alkali-induced mercerization was found to cause partial lattice conversion to cellulose II, and the ratio of lattice conversion (L.C.R.) increased with the degree of delignification. The L.C.R. value reaches slightly more than 50 %, when one third of the lignin is removed, and the removal of about two third of the lignin from wood results in an almost complete conversion. The effect of lignin removal on lattice conversion was similar among the wood species, irrespective of their density and lignin content, Introduction of acyl groups larger than caproyl into wood, followed by saponification and mercerization resulted in a high conversion of cellulose in wood from cellulose I to cellulose II.     

Modification of Poplar Wood Using Polyhexahydrotriazine and Its Effect on Hygroscopicity

Chemical modification is an efficient method for improving the properties of wood. In this study, poplar sapwood was modified via paraformaldehyde, 4,4′-oxydianiline (ODA), and N-methylpyrrolidone solvents through a vacuum-pressure impregnation process. The poplar sapwood underwent a curing process producing the ODA polyhexahydrotriazine polymer, which is a strong thermosetting material. The results showed that the weight percent gain of the modified poplar sapwood was 223.3%. The density of the modified wood specimen increased from 356.8 kg/m³ to 445.0 kg/m³. The water absorption decreased from 159.6% to 0.9% due to the thermosets penetration into the lumen and the cell walls of the wood. Additionally, condensation reactions occurred between the aldehyde groups of the paraformaldehyde and the hydroxyl groups of the poplar wood. The results showed that the modified wood achieved stronger waterproof properties than the unmodified wood.     

香蕉假茎苯酚液化及其产物树脂化制备胶黏剂

以苯酚为液化试剂、硫酸为催化剂对香蕉假茎进行液化,探讨液化条件对液化反应的影响,并结合傅里叶红外光谱(FT-IR)、热重分析(TGA)和成分分析研究了不同液化时间的液化物性质差别,同时以液化产物制备环氧树脂胶黏剂,并对其性能进行表征。单因素试验结果表明:优化条件为催化剂用量(占原料的质量分数)30%、反应温度150℃、液固比4:1和液化时间90 min; FT-IR分析表明:40 min和90 min液化产物官能团相似且具有芳香衍生物和酚羟基特性;成分分析和TGA分析表明:40 min残渣中纤维素保留量比90 min高;性能测试表明,90 min液化产物环氧树脂胶黏剂的剪切强度可达7.26 MPa,玻璃化温度(T_g)可达78℃。在优化的反应温度、催化剂用量和液固比的条件下,液化时间对残渣率和液化产物官能团的影响较小,但对残渣中纤维素含量的影响较大,液化产物适合制备生物质环氧树脂胶黏剂。     

Catalytic Liquefaction of Coal and Refining of Products

Abstract

I have been asked to consider the present state of the art in the catalytic liquefaction of coal and refining of products by catalytic means and to suggest some directions for research and development in this very important area of our energy program. This is a large order, as any review of what has been done and what is known about coal liquefaction will quickly show. Coal liquefaction by catalytic means has a long history and has been prached on a commercial scale in various parts of the world. It has had a profound influence on the processing of petroleum. In developing this subject and trying to discern new directions it is very worthwile to review briefly the history of coal liquefaction by catalysis to determine how we have arrived at the present state. By doing this we can also gain knowledge of the constrains imposed on successful developments in this area. It should therefore be possible to determine dirctions for making the processes simpler amnd easier. If nothing else, it will make our attempts to see new things more efficient. Furthermore, the history of coal liquefaction is very interesting and is worth reviewing for itself.     

Catalytic Liquefaction of Coal and Refining of Products

I have been asked to consider the present state of the art in the catalytic liquefaction of coal and refining of products by catalytic means and to suggest some directions for research and development in this very important area of our energy program. This is a large order, as any review of what has been done and what is known about coal liquefaction will quickly show. Coal liquefaction by catalytic means has a long history and has been prached on a commercial scale in various parts of the world. It has had a profound influence on the processing of petroleum. In developing this subject and trying to discern new directions it is very worthwile to review briefly the history of coal liquefaction by catalysis to determine how we have arrived at the present state. By doing this we can also gain knowledge of the constrains imposed on successful developments in this area. It should therefore be possible to determine dirctions for making the processes simpler amnd easier. If nothing else, it will make our attempts to see new things more efficient. Furthermore, the history of coal liquefaction is very interesting and is worth reviewing for itself.     

Raman Spectroscopic Studies on the Formation Mechanism of Hydrous-Zirconia Fine Particles

The Raman spectra of hydrous-zirconia fine particles produced by the hydrolysis of various ZrOCl₂ solutions were investigated. The Raman spectra of hydrous zirconia synthesized at HCl concentrations below 1 mol/L were similar to those of monoclinic, crystalline ZrO₂; those of hydrous zirconia synthesized at HCl concentrations greater than 1 mol/L showed a crystal structure change. The line width of the Raman bands increased with increasing H⁺ ion concentration. Analyzing the relationship between Raman band width and particle size revealed that the primary particle size of hydrous zirconia was controlled by the H⁺ and Cl⁻ ions, because these ions interfered with the polymerization in a hydrolysis reaction. Based on the experimental results, the formation mechanism for primary particles of hydrous zirconia was determined.     

氧化纤维素的制备研究

介绍了氧化纤维素 (DAC)的制备过程 ,用正交法探讨了以NaIO4 作氧化纤维素时反应温度、溶液pH值、氧化剂浓度、反应时间以及交互作用对DAC醛基含量的影响 ,找到了影响醛基含量的主要因素为反应温度、反应温度与NaIO4 的交互作用、反应温度与溶液 pH值的交互作用。初步确定了制备氧化纤维素的反应工艺 ,使醛基含量较高时的最佳反应条件为 :反应温度 3 5℃ ,反应时间 3h ,NaIO4 质量分数 6.78% ,pH值为 2时 ,醛基含量达 68.2 0 %。     

Study on Dissolution and Regeneration of Poplar Wood in Imidazolium-Based Ionic Liquids

Abstract

We tested dissolution and regeneration of poplar wood using 1-butyl-3-methylimidazolium chloride ([C₄mim]Cl) and 1-butyl-3-methylimidazolium acetate ([C₄mim]OAc). When 5wt% of poplar sawdust in [C₄mim]OAc was stirred at 130°C, 96wt% of added poplar was dissolved in [C₄mim]OAc, whereas 25.3wt% of poplar dissolved in [C₄mim]Cl at the same reaction condition. Fourier transform infrared spectroscopy (FT-IR) and lignin content analysis revealed that poplar was partially delignified during the dissolution and regeneration processes. X-ray diffraction (XRD), thermal gravimetric analysis (TGA), and microscopy were used to characterize raw poplar sawdust, undissolved poplar, and regenerated wood from the poplar-ionic liquid solution. The direct acetylation of poplar-[C₄mim]OAc solution using acetyl chloride was also performed in the absence of any organic solvent. FT-IR analysis of the resulting wood sample revealed the formation of partially delignified acetylated-poplar.