酶促木质素与酚聚合反应分子量及分布实验

在反相微乳液系统中 ,进行了过氧化物酶催化木质素与酚共聚反应实验 ,考察了酶浓度、WO(水 /表面活性剂 ,质量比 )、表面活性剂浓度、单体 (酚、木质素 )浓度及醇烃比对聚合物分子量的影响。结果表明 ,聚合物重均分子量可用表面活性剂浓度、酶浓度、单体浓度及油相中醇烃比来调控。用单纯形优化法关联了实验数据 ,得到了聚合物重均分子量的关联式 :M =6 2 7× 10 4 (Y1× 10 7) -0 .3 4Y0 .982 Y0 .83 Y2 .4 64 Y1.0 55。聚合物分子量分布出现双峰 ,是两种反应机理竞争的结果。     

反相微乳液酶催化合成木质素-对甲酚共聚物

采用一种全新的反相微乳液体系 :十六烷基三甲基溴化铵 正丁醇 异辛烷 水 ,用辣根过氧化物酶催化合成木质素对甲酚共聚物 ,证实了反应的可行性。红外光谱的结果表明木质素与对甲酚发生了聚合反应 ,差示扫描量热分析的结果表明引入对甲酚改善了木质素的热性能。讨论了该聚合过程中酶浓度 ,活性剂浓度 ,W0 :c(H2 O) c(CTAB) ,酚浓度 ,木质素浓度 ,醇烃比对分子量的影响 .回归实验数据得出控制分子量大小的关联式 ,平均偏差为 8.7%。     

过氧化酶催化木质素与酚聚合反应速率研究

进行了过经物酶催化木质素与酚聚合反应研究,结果表明在微乳液系统中酶促反应速率很大。     

麦草碱木素酚化改性及其制备LPF胶粘剂工艺研究

利用碱性条件下酚化改性的麦草碱木素代替部分苯酚制备了高木质素/苯酚比例和胶粘强度高的木质素酚醛树脂(LPF)胶粘剂.利用傅立叶红外光谱(FT-IR)和凝胶色谱(GPC)研究了麦草碱木素在碱性条件下酚化改性前后的结构变化.FT-IR分析表明,麦草碱木素发生了酚化反应,伴随着酯基的断裂和甲氧基的脱落;GPC结果显示,木质素平均分子量降低,分子量分布范围变宽.接着,研究了木质素/苯酚比例、氢氧化钠浓度、甲醛/木质素比例、酚化温度、酚化时间、缩聚温度、缩聚时间等反应工艺参数对LPF胶粘剂性能的影响,优化了麦草碱木素酚化改性制备LPF胶粘剂的反应工艺参数.最后,比较了反应工艺参数优化的LPF胶粘剂与传统PF胶粘剂的各项性能,结果显示,麦草碱木素酚化改性后代替70 % 的苯酚制备得到的LPF胶粘剂的胶粘强度与传统PF胶粘剂相近.     

新型聚氨酯助剂——酶解木质素的研制

研究了采用无机碱性水溶液和有机溶剂从玉米秸秆发酵制备乙醇的残渣中分离得到酶解木质素的方法.结果表明,用有机溶剂提取后的残渣继续用无机碱水溶液再次提取,酶解木质素的产率为25%～35%,其红外光谱与磨木木质素红外光谱相似.酶解木质素的分子中含有丰富的苯环、酚羟基和醚键等官能团,具有较高的反应活性,能直接用于聚氨酯的改性.     

EA-AA共聚物增容的PVC-木质素共混物的热稳定性

木质素分子中含有阻碍酚结构,可抑制基于自由基连锁机理的反应。而聚氯乙烯(PVC)的热降解属于自由基反应,因此用木质素与PVC共混,共混物的热稳定性应高于PVC,但PVC与木质素直接共混物的热稳定性一般都劣于PVC。制备了丙烯酸乙酯(EA)-丙烯酸(AA)共聚物乳液并用其对木质素粉末进行包覆处理。用处理后的木质素与PVC进行共混制备成PVC-木质素共混物。用热重分析法研究了共混物的热稳定性,并据扫描电子显微镜观测结果,结合木质素分子结构推测了共混物热稳定性的改善机理。结果表明,木质素用EA-AA共聚物处理后,共混物的热稳定性得到了明显改善,且优于PVC参照样(其初始分解温度和最大分解速率温度分别比PVC参照样高13℃和27℃左右)。扫描电子显微分析表明,木质素经丙烯酸酯共聚物处理后,与PVC的相容性改善显著,在PVC基体中分散良好。木质素羟基与EA-AA共聚物羧基的结合和分散颗粒的减小有效减弱了木质素的脱水作用,抑制了它对PVC的自催化脱氯化氢的促进作用,从而有效发挥了它的阻碍酚结构对PVC自催化脱氯化氢过程的抑制作用。     

玉米秸秆木质素的漆酶/介体活化处理

采用漆酶配以不同的介体对玉米秸秆木质素进行活化处理,利用红外光谱(FTIR)、紫外光谱、凝胶渗透色谱(GPC)、热失重(TG)、示差扫描量热(DSC)等分析方法研究了介体对漆酶活化降解木质素的影响。结果表明,漆酶会使木质素发生脱甲基作用,降低木质素的相对分子质量,增加酚羟基的含量,但在解聚木质素的同时也伴随着再聚合作用。在漆酶活化木质素的过程中,介体作为传递电子的中间体,能够促进木质素的氧化降解,降低木质素的相对分子质量,提升羟基的反应活性。不同的介体,活化效果不同,HBT、香草醛和紫丁香醛三种介体中,HBT介体的活化效果最佳。     

玉米芯酶解残渣酚化改性工艺及产物结构表征

以玉米芯纤维素酶水解残渣为原料,利用对甲酚和硫酸对其木质素进行酚化改性。采用单因素和正交试验的方法探讨了硫酸浓度、反应温度、反应时间和硫酸用量对酚化改性产物的得率、酚―羟基含量的影响。利用FTIR、1H-NMR和GPC等手段对酚化木质素的结构进行表征。研究结果表明,酚化改性可以有效地提高木质素的酚羟基含量,降低木质素大分子的分子量。正交实验结果表明,反应温度对酚化改性的影响最大,其次是硫酸浓度,酚化改性的最佳工艺条件为:温度40℃,硫酸质量分数60%,时间60 min,硫酸用量20 mL/g(残渣),此条件下木素酚得率达53.85%,酚羟基含量为1.23 mol/C9,相对分子质量(w M)为3388。     

温度对二氧化碳酸析提取黑液中木质素的影响

以碱法制浆的松木黑液为原料,用二氧化碳酸化黑液提取其中的木质素,考察了反应温度(40~80℃)对酸析木质素产率及其无机盐和糖分等含量的影响,采用凝胶渗透色谱(GPC)、离子色谱仪(IC)、元素分析仪和热重分析仪(TG)对木质素产物进行结构表征。结果表明,温度升高不利于木质素析出,产率下降;但较高温度下制备的木质素中无机盐、糖分及硫含量低,纯度高;同时温度越高,木质素相对分子质量越大,甲氧基含量增大,但酚羟基含量减小。TG和DTG曲线显示,反应温度升高木质素最大失重速率增加,残余量减少。     

木质素磺酸钙与环氧丙烷共聚的研究

以马尾松木质素磺酸钙与环氧丙烷为起始原料进行共聚反应。研究了木质素结构特性和共聚方法对产物结构持性的影响。结果表明,木质素磺酸盐的酚羟基是主要的反应点,而芳香环基本上没有变化。连续法加科比一步法容易得到分子量较高的产物,但一步法进行的速率较高。     

工业碱木素热化学转化制备酚类化学品

引言 工业碱木素是碱法制浆过程中产生的重要副产物之一,其排放污染问题越来越受到关注,目前工业处理方法只是将其浓缩燃烧以回收能源和残碱.木质素是一种化学结构复杂的天然高分子聚合物(主要由愈创木基丙烷、紫丁香基丙烷和对羟苯基丙烷通过醚键和碳碳共价键相联),其分子量从几千至几十万,数量上仅次于纤维素,利用潜力较大.     

铜铁复合层柱粘土的制备及其在含酚废水处理中的应用

以蒙脱石为原料，利用共聚法合成了铜铁复合层柱粘土催化剂。通过XRD、FTIR和N₂吸附-脱附等检测方法对其结构进行了表征。结果证实，交联剂成功插入到蒙脱石层间，所得催化材料具有较大的比表面积。将其作为催化剂，采用催化湿式过氧化物氧化处理含酚废水,实验结果表明，与铁、铁铝等层柱粘土相比，铜铁复合层柱粘土在苯酚处理浓度、催化剂用量、反应时间以及初始pH适用范围等方面都有较大的改善。在最佳工艺条件下，苯酚去除率可达99%，pH＝3~9都具有较高的去除效果，平均去除率达97%以上，循环使用四次后去除率仍大于90%。     

Eucalyptus bark lignin substituted phenol formaldehyde adhesives: A study on optimization of reaction parameters and characterization

The major adhesive resin worldwide used in the manufacture of plywood is phenol formaldehyde resole (PF) resin. The raw material for this kind of adhesive is derived from petroleum oil. Because of rising prices of crude oil and the scarcity of petroleum products, their replacement by natural resource–based raw material has become a necessity. In the present work, the possibility of replacing phenol in PF resin with lignin was explored. The parameters for preparation of bark lignin substituted PF (LPF) adhesive, such as lignin concentration, formaldehyde to phenol molar ratio, catalyst concentration, reaction time, and reaction temperature, were optimized. It was found that up to 50 wt % of phenol can be substituted by lignin to give an LPF adhesive with better bonding strength compared to that of control PF resin. Prepared resins were characterized using IR, DSC, and TGA. IR spectra of LPF adhesive showed structural similarity with that of PF adhesives. Thermal stability of LPF adhesive was found to be lower compared to that of control PF (CPF) adhesive. DSC studies revealed a lower curing temperature for LPF resin than that for CPF resin. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3514–3523, 2004     

Development and characterization of a wood adhesive using bagasse lignin

Bagasse is spent fiber left after extraction of sugar. It is mainly used as a fuel to concentrate sugarcane juice. In the present work, the possibility of preparing wood adhesives from bagasse has been explored. The parameters for the preparation of a lignin phenol formaldehyde (LPF) adhesive, (lignin concentration, formaldehyde to phenol molar ratio, catalyst concentration, reaction time and reaction temperature) have been optimized. It was found that up to 50% of phenol can be substituted by bagasse lignin to give LPF wood adhesive having better bonding strength in comparison to a control phenol formaldehyde (CPF) wood adhesive. Prepared resins were characterized using IR, DSC and TGA. IR spectra of LPF resin showed structural similarity with CPF resin. Thermal stability of LPF resin was found to be lower as compared to CPF resin. DSC studies reveal a lower curing temperature for LPF adhesive in comparison to CPF adhesive. A shelf-life study reveals that LPF exhibits consistent behavior as compared to CPF in respect to adhesive strength.     

Waste liquors from cellulosic industries. IV. Lignin as a component in phenol formaldehyde resol resin

The lignin separated from the spent liquor of soda pulping of rice straw can replace a part of phenol in the condensation reaction with formaldehyde in a basic medium to form phenol lignin–formaldehyde (PL–F) resol resin. The production of phenol lignin–formaldehyde resol resin was carried out in two stages: First was the formation of the adduct (lignin phenol) using different lignin percentages; second was the condensation of the adduct with formaldehyde. Reaction variables, i.e., molar ratio of formaldehyde to phenol lignin, polymerization time, amount of sodium hydroxide as a catalyst, and polymerization temperature in the polymerization step were studied. Solubility of the produced resol resin in different solvents, its viscosity, and yield were determined. Lignin could replace up to 40% of phenol in the produced resin. Infrared spectra of the prepared resin were determined. Structural similarity of phenol–formaldehyde to phenol lignin–formaldehyde resin was shown. Also, relative absorbance of characteristic bands of the resins were calculated and claimed too much on the effect of reaction parameters on the prepared resins.     

催化剂形态与酚类化合物加氢反应活性构效关系的研究进展

木质素是一种重要的生物质可再生资源,其降解后得到的酚类物质加氢后可得大量高附加值化学品,在环境治理和原料利用方面都有着十分重要的影响。本文综述了近年来国内外木质素酚类加氢反应催化剂的研究进展,总结了液相酚类催化加氢催化剂的种类、反应机理及结构敏感性因素对酚类催化加氢反应活性的影响,阐述了催化剂颗粒尺寸对液相酚类加氢反应活性影响,并以木质素液相酚类加氢反应催化剂的活性金属和载体为体系,对现有的结构敏感性反应中催化剂存在的形貌效应、晶相效应进行了讨论。提出未来可通过控制催化剂形貌和晶相来研究催化剂形态与催化活性之间的构效关系,为今后设计高活性木质素液相酚类加氢催化剂提供借鉴和参考。     

Acid‐catalyzed liquefaction of waste paper in the presence of phenol and its application to Novolak‐type phenolic resin

Liquefaction of waste paper (WP) was performed in the presence of phenol with an acid catalyst. Newspaper (NP) was liquefied more easily than box paper (BP) or business paper (BNP). Differences in the degree of liquefaction were due to different chemical compositions. That is, NP had a relatively high lignin content, which is known to be easily liquefied, whereas BP and BNP were mainly composed of cellulose with a crystalline structure, which is difficult to liquefy. The acid concentration and phenol/WP ratio were more important factors in the regulation of liquefaction than reaction temperature. The changes in the apparent molecular weight depending on the reaction time were more significant for phenolated NP, with high lignin content, than for phenolated BP. The obtained phenolated products showed thermal flow properties and reactivity as good as those of phenolated wood and commercial Novolak resin. Thermosetting moldings were obtained from phenolated products, and their flexural properties and thermal stability were comparable to those of phenolated wood and commercial Novolak resin. Flexural properties were further improved by the cocondensation reaction between the unreacted phenol of phenolated products and formaldehyde. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1473–1481, 2002     

秸秆苯酚选择性液化研究

苯酚液化是生物质液化的重要手段,农作物秸秆是一种不均一的原料,而完全液化将其看作是 "单一"的原料,针对这一问题本研究采用选择性液化处理方式对小麦秸秆进行了苯酚液化,并对比了选择性液化与完全液化。结果表明:低温下适当的浓硫酸用量、较高的苯酚用量、适当的反应时间有利于保留纤维素而选择性液化半纤维素和木质素;与完全液化处理方式相比,选择性液化反应条件温和,保留了大量的纤维素,大大提高了原料利用价值。通过均匀试验和数据回归分析并实验验证得到选择性液化优化条件为:浓硫酸用量占总反应体系质量分数的 3.0%,反应温度 100℃,反应时间 30 min,苯酚与秸秆质量比 3:1,纤维素残留率达 70%,而液化产物结合酚质量分数可达 100%。     

Alkylation of phenol with tert‐butyl alcohol over a catalyst synthesized from coal fly ash

The alkylation of phenol with tert‐butyl alcohol was carried out in a continuous flow reactor over a catalyst synthesized from fly ash. The activity of the synthesized catalyst was compared with those of other conventional zeolite catalysts such as 13X (NaX) and Hβ. Of all the catalysts tested, zeolite Hβ showed the highest activity in phenol conversion followed by the synthesized zeolite (HZOP‐31). The activity of commercial 13X zeolite was found to be same as that of HZOP‐31. Ce‐exchanged catalyst (CeZOP‐31) showed even better performance than 13X in the alkylation of phenol. The effects of different parameters such as reactant mole ratio, temperature and space velocity on phenol conversion and tert‐butyl phenol selectivity were studied. The effect of mass transfer resistance was found to be negligible within the feed rate range and particle size range studied. The apparent activation energy for the reaction of tert‐butyl alcohol over HZOP‐31 was determined as 30.1 kJ mol^?1. Copyright © 2006 Society of Chemical Industry