木质素基环氧树脂的合成与应用

木质素是一种储量丰富的多酚类天然高分子材料,以木质素为原料合成的木质素基环氧树脂具有原料可再生、成本低、可降解等特点。本文从木质素直接环氧化以及通过酚化、酯化、丙氧基化等改性后再环氧化这2方面综述了木质素基环氧树脂的合成与应用,并对其未来的发展进行了展望。     

木质素基表面活性剂研究现状

木质素作为一种天然高分子化合物,其来源丰富,可以用来代替石油资源制备表面活性剂,缓解当前石油资源枯竭的问题。常见的木质素基表面活性剂有阳离子表面活性剂、阴离子表面活性剂、两性离子表面活性剂以及非离子表面活性剂。木质素基表面活性剂在工业领域具有广泛的应用范围,可以作为染料分散剂、混凝土减水剂、沥青乳化剂以及原油采集过程中的驱油剂等。木质素基表面活性剂的开发利用为生物质产品的高值化利用开辟了一条新的路径。     

木质素基碳材料催化剂的制备及应用研究进展

木质素具有三维网状苯环结构、来源丰富、含碳量高、官能团丰富可控等特点,是一种理想的碳材料前体。通过化学改性和微结构调控制备具有特殊功能的木质素基碳材料,其在能源催化转化、电化学储能和环境修复等领域应用广泛。本文介绍了木质素基碳材料催化剂的国内外最新研究进展,总结了木质素基碳材料催化剂的制备方法,重点综述了木质素基碳材料催化剂在氧化反应、氢解反应、酯化反应、水解反应、脱水反应、费托合成等热催化反应、电解水析氢和锌空气电池氧还原等电催化反应、有机污染物降解等光催化反应的研究进展,但如何构筑高效、稳定、廉价、可规模生产的木质素基碳材料催化剂仍然是一个具有挑战性的课题。文章总结：今后研究中应加强对木质素的基础化学结构和微结构调控、活性组分与木质素碳材料载体间的相互作用、木质素基碳材料催化剂在催化反应中的作用机理等的研究,更好地发挥其低成本、三维结构易成型和微结构可调控等优势,拓展木质素生物质资源的高值化利用领域。     

木质素基活性炭氮掺杂改性及其电化学性能

以磷酸法木质素基活性炭为原料,三聚氰胺为氮源、KOH为活化剂,采用同步掺杂方式制备了氮掺杂活性炭(NAC)。通过BET、XRD、拉曼光谱和XPS表征手段测试了改性后活性炭的结构及其组分,并通过电化学表征手段,测试了其作为超级电容器电极材料在几种不同性质电解液中的性能,初步探究了电解液对电极材料电化学性能的影响机制。实验结果表明：改性后的活性炭具有丰富的孔结构,比表面积达到2 332 m²/g,微孔孔容为1.37 cm³/g,中孔孔容为0.74 cm³/g,平均孔径为2.79 nm,含氮元素7.5%,其中类石墨型氮(N-Q)结构达到34.6%。丰富的孔结构和氮含量大幅提升了活性炭的电化学性能,其在水系电解液中展现出了高比电容,在1 A/g的电流密度下比电容最高可达424 F/g;在有机系电解液中,尽管其在1 A/g的电流密度下比电容最高仅为87 F/g,由于其工作电压窗口更宽(0～2.5 V),因此具备了更高的能量密度。对结果进行分析,发现：活性炭电极材料在水系电解液中的性能主要受电解液水合离子半径影响,而在有机系电解液中...     

Lignin-based copolymer adhesives for composite wood panels – A review

Lignin is a natural and renewable organic compound that can be easily obtained from spent pulping liquors. It can be used as feedstock for making wood adhesives. Nonetheless, lignins need to be modified to enhance reactivity prior to being used as feedstock for making wood adhesives. Appropriate crosslinkers are also needed to ensure the bonding quality of the lignin-based wood adhesives. In the present review, the drawbacks of using lignins alone as wood adhesives, modifications to enhance the reactivity of lignins and production of lignin-based copolymer adhesives for composite wood panels are reviewed and discussed. The objective of this review is to provide background information about the recent status on the development of lignin-based copolymer adhesives for the production of composite wood panels as well as the future prospects of these adhesives in industry. Several modifications such as demethylation, oxidation, methylolation, phenolation, reduction and hydrolysis have shown promising results for enhancing the reactivity of lignins. Several crosslinkers such as phenolic resin, tannin, polymethylene polyphenyl isocyanate (pMDI), furfural and ethylenimine are capable of copolymerizing with lignins to produce lignin-based wood adhesives. The performance of composite wood panels bonded with modified lignin-based copolymer adhesives have been shown to meet the requirements of relevant standards. The main obstacles for the composite wood panels industry to widely adopt to lignin-based copolymer adhesives are the economic and technical issues. Nevertheless, lignin modification methods are proving to enhance the reactivity of lignins and the optimization in such modification methods would justify the economic issue. Together with the public awareness on the safety, health and environment concerns, the utilization of lignin-based adhesives in the composite wood panels industry is feasible.     

木质素衍生吸附材料及其在废水处理中的应用研究进展

木质素是一种广泛存在于植物中的天然酚类高分子,具有来源广泛、含氧官能团丰富、含碳量高等优点。对木质素进行修饰改性、复合、热解炭化能够获得性能优异的木质素衍生吸附材料,在废水处理中具有广泛的应用前景。本文对木质素的分子结构特点进行了概述,总结了木质素基吸附剂的种类及其制备方法,详细介绍了木质素基吸附剂的修饰改性方法,如金属离子、含N、O、S官能团表面修饰以及复合改性等,并综述了木质素基吸附剂在染料、药物、重金属废水处理中的应用研究。最后,对木质素衍生吸附材料目前存在的问题以及未来的研究方向进行了总结和展望,如何实现木质素衍生吸附剂的可控制备和规模化生产,提高吸附剂在实际环境中的适用性是未来的主要研究内容。     

改性木质素合成环氧树脂的研究

以三氟化硼乙醚为催化剂,丙氧基化改性的麦草碱木质素与环氧氯丙烷反应合成木质素基环氧树脂。经单因素实验确定了醚化和环化温度分别为60℃和30℃。通过五因素四水平的正交实验确定了最优反应条件,最优反应条件下所得产物的环氧值达0.44。     

Shell–core structured carbon fibers via melt spinning of petroleum- and wood-processing waste blends

In the last decades, carbon fibers with light weight and high strength have experienced the largely increased uses in various industrial applications. However, their expected uses in the automotive industry and building are largely limited because of their high production cost. Herein, we have demonstrated an effective method of making low cost carbon fibers via the melt spinning of petroleum-processing residue (pyrolyzed fuel oil, PFO)/lignin blends. Careful selection of tetrahydrofuran as the solvent to dissolve both PFO and lignin was made to optimize the miscible blend. The melt spinnable blend with a softening point of 260–280 °C exhibited good spinning ability at 280 °C. The plasticizing function of PFO allowed the highly cross linked lignin-based pitch to have high fluidity in the melt spinning process. Based on detailed TEM observations, the thermally treated fiber prepared at 2800 °C exhibited a shell–core structure, consisting of a highly crystalline surface from PFO and an amorphous disordered core from lignin. Such a crystalline surface structure gave rise to a high modulus value (up to 100 GPa) to the prepared carbon fibers.     

Preparation and performance evaluation of a lignin-based solid acid from acid hydrolysis lignin

A new lignin-based solid acid was prepared by sulfonation of sulfuric acid lignin (a typical acid hydrolysis lignin). The solid acid has been characterized by scanning electron microscopy (SEM), powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), mercury injection apparatus, and elemental analysis. Structural analyses suggest that the material with high thermal and hydrothermal stability is composed of amorphous phenylpropane-based polymers with sulfonic acid groups. Catalytic tests in esterification of acetic acid with ethanol and hydration of 2, 3-dimethyl-2-butene show that the lignin-based solid acid exhibits high catalytic activities in acid-catalyzed reactions, which can be used as a replacement for the conventional solid acid catalysts. This may be attributed to good accessibility of reactants to sulfonic acid groups in the material structure.     

工业碱木质素合成环氧树脂的研究

以工业碱木质素（LG）为原料．先用环氧丙烷（P（））在2MPa下对LG改性获得丙氧基化木质素（HLG）,再将HLG与环氧氯丙烷（ECH）进行反应合成了木质素基环氧树脂（LGEP）;用红外光谱、紫外可见吸收光谱对LGEP的结构进行了表征,并用盐酸一丙酮法测定了LGEP的环氧值（EV）。通过正交实验确定LGEP的最佳合成条件为;m（ECH）：m（HLG）=3．5：1、m（KOH）：m（HLG）=1;1、反应时间3h、反应温度80℃,在此条件下制得的LGEP的环氧值最高。为0．397。     

木质素基材料在混合型超级电容器电极材料中的研究进展

木质素是一种多酚聚合物,具有丰富的芳香类官能团和含氧官能团,且在碳化后形成的多孔碳材料易于转化为石墨化碳层,从而形成局部高导电区域,是制备超级电容器的优质前体,故将木质素用于混合型超级电容器逐渐成为研究热点之一。本文综述了近年来木质素碳材料在混合型超级电容器电极材料中的应用,重点分析了木质素在其中的作用,将其总结为3类进行介绍,包括木质素/多孔炭（石墨烯、碳纳米管）型、木质素/金属化合物（金属氧化物、硫化物、氢氧化物）型和木质素/导电聚合物（聚苯胺、聚吡咯、聚噻吩）型。此外,还介绍了木质素基混合型超级电容器在柔性超级电容器中的应用。最后,总结了木质素基材料应用在混合超级电容器中的优势和挑战。     

间苯二甲腈结晶精制工艺

气相氨氧化法生产间苯二甲腈存在产品纯度低、废水排放量大等问题。文中在实验研究的基础上,从溶剂的溶解特性及结晶提纯效果出发,筛选出了以乙醇和水的复合溶剂为间苯二甲腈的结晶溶剂,通过加热溶解、降温结晶、离心过滤及溶剂回收等工艺过程,精制后的间苯二甲腈纯度(质量分数)可达99.5%以上,满足了国际市场的要求,废水排放量也由每1 000 kg产品40 000 kg降至1 100 kg。     

Engineering Plastics from Lignin. IX. Phenolic Resin Synthesis and Characterization

The performance of phenol-formaldehyde (PF) resins, formulated with lignin derivatives previously synthesized as phenolic resin prepolymers, was evaluated by thermal analysis of the curing process, and by a hard maple shear block test. At 54 and 60% phenol replacement levels, respectively, kraft (KL) and steam explosion lignin (SEL)-based resoles exhibited cure behavior very similar to a standard PF resin. Acid hydrolysis lignin gelled prematurely, and was found to be incompatible with the normal synthesis procedure. Differential scanning calorimetry (DSC) was used to compare kinetic parameters for the curing process of neat and lignin derived phenolic resins. Activation energies and cure rates determined by DSC showed no difference between adhesives. High lignin contents had no inhibitory effect on resin cure. Shear strength properties were evaluated in a compression test, and results illustrate that both lignin-based resins have acceptable strength properties, both in a dry and accelerated aging test. Of the lignins tested, kraft lignin consistently demonstrated superior performance as a pre-polymer in phenolic adhesives. This was attributed to differences in the chemical structure of the two lignins, which had been found to vary in terms of their reactivity with formaldehyde and phenol. KL had been noted to be more amenable to derivatization with formaldehyde and phenol, hence its ability to crosslink with a phenol-formaldehyde fraction during resin synthesis was increased. Positive structural features in KL are a high phenolic guaiacyl (3-methoxy, 4-hydroxy phenyl) content, low carbon-to-carbon bonding between aromatic rings, high solubility in alkali, and a higher number average molecular weight than SEL.     

Sulfonation of Phenolated Kraft Lignin to Produce Water Soluble Products

Kraft lignin is water insoluble and has limited end-use applications. To produce water soluble lignin-based products, the modification of softwood kraft lignin through phenolation followed by sulfonation of sulfuric acid or sodium sulfite treatment were investigated in this work. Fourier transform infrared (FTIR) spectrophotometer, nuclear magnetic resonance (NMR), and thermo-gravimetric analysis were also considered for characterizing the lignin-based products. The results showed that phenolation pretreatment was effective to generate sulfonated lignin (SAP-lignin) by sulfuric acid treatment with a high charge density (3.12 meq/g) and solubility, which is due to the addition of sulfonation sites on the phenolic ring. However, sodium sulfite treatment of phenolated lignin generated sulfonated lignin (SSP-lignin) with the charge density of 1.20 meq/g due to hindered sulfonation by occupation of reactive α-position. SAP-lignin was soluble across the tested pH range of 1–13, but SSP became insoluble at a pH lower than 3. Thermogravimetric analysis revealed that phenolation pretreatment reduced the thermal resistance of modified lignin when compared to kraft lignin, while SAP-lignin exhibited the highest thermal resistance due to condensation under sulfuric acid treatment. SAP- and SSP-lignin were successfully used as a coagulant for dye removal from simulated solutions as they could remove 72.1 and 90.4% of ethyl violet from a simulated dye solution, respectively.     

木质素基活性炭研究进展

木质素是制浆造纸工业的副产物,是地球上最丰富的可再生资源之一。本文简要介绍木质素的结构及其性质,并论述了木质素吸附材料的吸附性能及吸附剂的研制,详细总结了木质素基活性炭吸附剂的研究进展并探讨了今后的研究方向。     

Sustainable lignin-based polyols as promising thermal energy storage materials

Six lignin-based polyols (LBPs) have been prepared by cationic ring opening polymerization of an oxirane in the presence of an organosolv lignin in tetrahydrofuran (THF) as reaction media and co-monomer. The prepared LBPs have been characterized and tested for the first time as phase change materials (PCMs) for thermal energy storage (TES) at low temperature. It was found a strong influence of the LBPs composition on their performance to storage thermal energy. Thus, LBPs with higher THF wt% content and lower oxirane/THF mass ratio exhibit the highest latent heats. Furthermore, a clear inversely proportional trend between the oxirane/THF mass ratio and the melting temperatures of the prepared LBPs was noticed. Among the prepared LBPs, the highest obtained latent heat was 53.7 J/g demonstrating the potential application of lignin as feedstock for PCMs preparation. To the best of our knowledge, this is the first time that a biomass derived PCM based on lignin has been studied and considered for TES applications at low temperature. LBPs show energetic solid–liquid transitions that point out their promising potential as bio-PCMs. This work paves the way to introduce new bio-based PCMs from lignin in TES systems, for example, in a more sustainable construction sector.     

A new modification method of exploded lignin for the preparation of a carbon fiber precursor

A lignin-pitch for carbon fiber was prepared in a high yield from exploded lignin on phenolysis followed by heat treatment under a vacuum. The lignin-pitch had an excellent spinnability in the melt state to form a fine filament. The green fibers were easily made infusible when heated in air at a relatively high heating rate (15-60°C/h). The lignin-based carbon fiber was produced in 43.7% of yield based on a starting material. The tensile strength was more than 400 MPa, indicating that the lignin-based carbon fiber is classified into a general purpose grade. © 1993 John Wiley & Sons, Inc.     

Thermoplastic and moisture-dependent behavior of lignin phenol formaldehyde resins

Bonding kinetics of thermosetting adhesives is influenced by a variety of factors such as temperature, humidity, and resin properties. A comparison of lignin-based phenol formaldehyde (LPF) and phenol formaldehyde (PF) adhesive in terms of reactivity and mechanical properties referring to testing conditions (temperature, moisture of specimen) were investigated. For this purpose, two resins were manufactured aiming for similar technological resin properties. The reactivity was evaluated by B-time measurements at different temperatures and the development of bonding strength at three different conditions, testing immediately after hot pressing, after applying a cooling phase after hot pressing, or sample conditioning at standard climate. In addition, the moisture stability of the two fully cured resins was examined. The calculated reactivity index demonstrated that LPF requires more energy for curing than PF. Further results indicate that lignin as substituent for phenol in PF resin has a negative impact on its moisture resistance. Additionally, the known thermoplastic behavior of lignin could also be detected in the behavior of the cured resin. This behavior is relevant for the adhesive in use and necessitates a cooling phase before testing the bonding strength development of lignin-based adhesive systems. © 2019 The Authors. Journal of Applied Polymer Science published by Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48011.     

木质素基功能材料的制备与应用研究进展

木质素是植物中含量第二大的天然有机高分子聚合物,以来源于制浆造纸和生物质炼制中的工业木质素为原料,制备具有特殊功能的高附加值材料,对木质素进行资源化高效利用、解决化石资源日趋紧缺及环境污染等问题具有重要意义。近年来,研究人员利用各种技术制备了许多种类的木质素基功能材料,如载药微胶囊、防紫外剂、抗老化剂、光催化剂载体、炭电极材料等。本文介绍了木质素基功能材料的国内外最新研究进展,总结了木质素基功能材料的不同制备工艺和应用领域,评述了木质素微观结构及制备工艺对材料结构特性和应用性能的影响。指出木质素基功能材料的研究是涉及多个学科交叉的前沿课题,但如何高效制备结构规整可控且性能优异的木质素基功能材料仍然是一个具有挑战性的课题。今后的研究应加强对木质素微观结构及其调控机理的研究,以便可以更好地利用其自身的三维网状结构和大量芳香结构等特性制备基于木质素特性的功能材料。     

木糖渣的有机溶剂预处理及酶解性能

木糖渣是玉米芯经稀酸处理提取木糖后的残余物,一般作为燃料焚烧以提供部分热能。由于其含有丰富的纤维素组分,故可通过生物转化来生产多种化工产品,但残渣中大量木素的存在严重抑制了纤维素酶的水解效率。采用一些有机溶剂预处理可将部分木素溶出,因而可改善物料的酶解性能。采用乙醇对木糖渣进行预处理,研究了预处理条件（如温度、时间、固液比等）对木糖渣化学组分和纤维素酶解转化率的影响,并与玉米秸秆和玉米芯等进行了对比。结果表明预处理降低了木糖渣的木素含量,在固液（质量/体积）比1︰8、处理液中乙醇浓度50%（体积）、预处理温度210℃、预处理时间60 min时,木素脱除率为53.26%,预处理后木糖渣在酶解72 h时的纤维素转化率达到84.42%,比预处理前提高 14.58%。研究还发现,与木糖渣相比,有机溶剂乙醇更适合用于玉米芯和玉米秸秆酶解前的预处理。