杉木液化产物用于胶粘剂制备的研究

研究用少量的苯酚液化木材及其产物用于胶粘剂制备的方法,在硫酸催化剂作用下,用苯酚液化杉木木粉,得到木材液化产物.在液化产物中加入适量的甲醛和氢氧化钠溶液制备热固性酚醛树脂.压板测试结果表明,由木材液化产物所得树脂的干状胶合强度令人满意,但经蒸汽循环试验后,湿状胶合强度尚达不到JAS标准的要求,在下阶段工作中,需进一步研究木材液化产物胶粘剂的改性以提高其胶合耐久性.     

生物质化学组分及其液化残渣的热重行为

分别对木粉主要组分（纤维素、半纤维素和木质素）及其在相同液化条件下的液化残渣的热重行为进行了研究。热重实验结果表明,木粉主要组分的热稳定性为：木质素 > 纤维素 > 半纤维素。木粉的热解过程可以认为是这3种主要组分热解行为的综合：木质素的热解比较缓慢,热解温度区间最宽,主要失重温度为250～630 ℃;而纤维素和半纤维素的主要热解温度分别为332～383 ℃和236～333 ℃。在液化反应过程中,木粉主要组分发生降解从易到难的顺序为：木质素 > 半纤维素 > 纤维素。在木粉的液化过程中,快速液化阶段主要与半纤维素和木质素有关,而液化残渣率的高低主要与纤维素液化程度有关。     

核桃壳液化及其与甲醛反应能力的研究

探讨了核桃壳在120℃、苯酚与核桃壳粉质量比为3/1和催化剂(浓硫酸,用量为苯酚的3%)存在下液化,通过分析液化体系内游离苯酚和残渣含量以及液化体系与甲醛反应能力发现,核桃壳的酚解和酚化反应主要发生在反应初期,以后逐渐减弱;液化体系内总的活性量由2部分组成,一是液化体系内游离苯酚贡献的活性量,二是体系内液化产物贡献的活性量。随着反应的进行,游离苯酚折算的耗醛量逐渐减少,液化产物的耗醛量逐渐增加,而总的液化体系中消耗甲醛的能力在逐渐减弱。     

Liquefaction of wood,synthesis and characterization of liquefied wood polyester derivatives

Liquefaction of Central‐European softwoods meal was performed using a mixture of diethylene glycol and glycerol and a minor addition of p‐toluenesulfonic acid as a catalyst. The liquefied wood was used as a replacement of a certain amount of the polyhydroxy alcohol in the polyester synthesis, enabled by the large number of hydroxyl groups that were available in the liquefied wood. Three different polyesters were synthesized by using adipic acid and phthalic acid anhydride as reagents. The products were characterized using FTIR, GPC/SEC, and viscosity measurements. The polyesters have hydroxyl values that were reduced due to esterification, from 1043 mg KOH/g of the liquefied wood to 400–800 mg KOH/g. Polyhydroxyl alcohols (22–23%) in the polyester formulations were replaced by wood derivatives. Such saturated polyesters are suitable for further use in polyurethane foam production. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Influence of wood species on the properties of biopolyurethane prepared from liquefied wood with residue

Biopolyurethane prepared from liquefied wood with the residue of the liquefied wood product was investigated in this article. Previous results indicated that the residue of the liquefaction product was composed mostly of compounds originated from lignin. The chemical structures of lignin in softwood and hardwood are different. The influence of soft‐ and hardwood species on the chemical structure and mechanical properties of biopolyurethane prepared from liquefied wood with residue was investigated by tensile testing and Fourier transform infrared spectroscopy. The experimental results showed that the liquefaction of softwood occurs within a shorter time than that of hardwood and the biopolyurethane prepared from softwood was harder than that prepared from hardwood, which suggests that the properties of the liquefaction product and biopolyurethane are influenced by the chemical structure of the lignin. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Investigation of liquefied wood residues based on cellulose,hemicellulose, and lignin

Chinese eucalyptus was subjected to a liquefaction process using glycerol/ethylene glycol (EG) as liquefaction solvent. The effects of various liquefaction conditions, including reaction time, liquefaction temperature, acid concentration, and liquor ratio on the chemical composition of liquefied wood residues were studied. The results showed that the whole liquefaction process took place in two stages, the liquefaction yield of wood depended on the reaction temperature, acid concentration and liquor ratio. With increased acid concentration the liquefaction yield, acid‐insoluble lignin, and hemicellulose content of the residues were increased, and the relative content of cellulose was decreased. Fourier transform infrared (FT‐IR) analyses of the residues showed that hemicellulose and lignin were almost decomposed at the initial stages of reaction. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Microwave heating in wood liquefaction

Microwave radiation was used as the sole heating source to achieve liquefaction of Central European hardwoods, with glycols and organic acid anhydrides, using phosphoric acid as the acid catalyst. Pulsed microwaves of 300–700 W power were applied for 5–20 min. The efficiency of liquefaction increased with higher microwave power, longer radiation time, and higher phosphoric acid addition. With minor amounts of added acid it was possible to achieve complete liquefaction in 20 min. The method was tested for different hardwood types, with a series of glycols and anhydrides, and was found to be generally applicable. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101:1051–1056, 2006     

Pretreatment of wood flour slurries prior to liquefaction

As part of the UDES-S solvolytic approach to wood fractionation and liquefaction, a pretreatment stage has been developed using a fed batch technique to produce high solids content slurries. By using a combination of temperature and shear stress across homogenizing valves, wood flour slurries of Populus spp having concentrations of 20-32% by weight in both paraffin oil and ethylene glycol have been produced. Optical and scanning electron microscopy have shown that the recirculation loop and homogenizing valve cause structural degradation, defibration and defibrillation of the original particles as well as partial solubilization of the wood components. The maximum wood flour concentration, attainable before plugging was observed in the small scale system used, was just below 36% by weight. High concentration slurries are a prerequisite in order to obtain realistic reactor space velocities in biomass liquefaction processes.     

Preparation of semirigid polyurethane foam with liquefied bamboo residues

Bamboo residues were liquefied by using a solvent mixture consisting of polyethylene glycol 400 and crude glycerol (4/1, w/w) with 98% sulfuric acid as catalyst at 160°C for 120 min. The liquefied bamboo had hydroxyl values from 178 to 200 mg KOH/g and viscosities from 507 to 2201 mPa S. The obtained bamboo‐based polyols were reacted with various amounts of polyaryl polymethylene isocyanate (PAPI), using distilled water as blowing agent, silicone as surfactant, and triethylenediamine and dibutyltine dilaurate as cocatalyst to produce semirigid polyurethane (PU) foams. The [NCO]/[OH] ratio was found to be an important factor to control the mechanical properties of PU foams. At a fixed [NCO]/[OH] ratio, both density and compressive strength of PU foams decreased with the increase of bamboo content. The microstructure of PU foams indicates that [NCO]/[OH] ratios are important for cell formation and chemical reactions. The uniformity and cell structure of the foams are comparable to their corresponding compressive strengths. Moreover, the thermogravimetry analysis showed that all the semirigid PU foams had approximately the same degradation temperature of about 250 to 440°C. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Solvent effects on liquefaction: Solubilization profiles of a canadian prototype wood,populus deltoides,in the presence of different solvents

Populus deltoides was treated with straight chain alcohols from methanol to n-hexanol, mono and triethanolamine, water, ethyleneglycol, acetone, cyclohexane and lactic acid. A batch reactor was used in all the runs and the temperature range used was from 100 to 320°C. A reaction ordinate concept was used to evaluate the treatment severities. The results of these experiments showed a significant influence of the solvent on the extent of liquefaction of wood as well as on the holocellulose and lignin contents of the residues. An attempt to relate the liquefaction profiles to the solubility parameters of the solvents is discussed.     

An overview of solid–liquid separation of residues from coal liquefaction processes

Direct coal liquefaction process typically produces mixed oils (60%) and gases (15%). The remainder is a high‐boiling viscous residue that contains oils, asphaltenes, unreacted coal, mineral matter and potentially valuable liquefaction catalyst. Effective separation of the components of the residue stream is important to the economic and environmental performance of the process. Solid–liquid separation technologies, such as filtration, hydrocyclones, centrifugation, critical solvent deashing and distillation have been reviewed in relation to their use in coal liquefaction processes. Individual operations used have not been completely satisfactory, and a better overall result is obtained when they are used in combination. © 2012 Canadian Society for Chemical Engineering     

Synthesis and cure kinetics of liquefied wood/phenol/formaldehyde resins

Wood liquefaction was conducted at a 2/1 phenol/wood ratio in two different reactors: (1) an atmospheric three‐necked flask reactor and (2) a sealed Parr reactor. The liquefied wood mixture (liquefied wood, unreacted phenol, and wood residue) was further condensed with formaldehyde under acidic conditions to synthesize two novolac‐type liquefied wood/phenol/formaldehyde (LWPF) resins: LWPF1 (the atmospheric reactor) and LWPF2 (the sealed reactor). The LWPF1 resin had a higher solid content and higher molecular weight than the LWPF2 resin. The cure kinetic mechanisms of the LWPF resins were investigated with dynamic and isothermal differential scanning calorimetry (DSC). The isothermal DSC data indicated that the cure reactions of both resins followed an autocatalytic mechanism. The activation energies of the liquefied wood resins were close to that of a reported lignin–phenol–formaldehyde resin but were higher than that of a typical phenol formaldehyde resin. The two liquefied wood resins followed similar cure kinetics; however, the LWPF1 resin had a higher activation energy for rate constant k₁ and a lower activation energy for rate constant k₂ than LWPF2. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

煤直接液化残渣的性质及利用现状

为了高效地利用煤直接液化残渣,从液化残渣的组成、结构特性、热解特性、溶解特性4个方面论述了液化残渣的物理化学性质的研究现状。研究发现:残渣在组成和结构特性上都保留了原煤的部分特性。在对直接液化残渣热解特性的研究中,论述了各种不同研究手段,例如热重分析仪、实验室移动床、小型焦炉、高压釜等对液化残渣的热解过程的研究进展及热解机理的解析现状。在对液化残渣的溶解性进行研究时,讨论了残渣溶解性研究的意义及其在各种溶剂中表现出的不同特征。最后论述了煤直接液化残渣的利用研究现状、分析了其潜在的高附加值利用方式、发展前景和存在的问题。     

Molecular weights and molecular weight distributions of liquefied wood obtained by acid-catalyzed phenolysis

By means of gel permeation chromatography analysis, the molecular weights and molecular weight distributions of liquefied wood obtained under various liquefaction conditions and species of catalysts were investigated in order to trace the change in the structural characteristics of the liquefied wood. The results indicated that during the liquefaction reaction, wood components were subjected to decomposition, phenolation, and recondensation. The intensities of these reactions depended greatly on the reaction conditions and the species of catalysts, and their competing result determined the structural characteristics of the resulting liquefied wood. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 351–357, 1997     

Resol‐type phenolic resin from liquefied phenolated wood and its application to phenolic foam

A liquefied wood‐based resol resin was prepared with excellent yield by a reaction of liquefied wood and formaldehyde under alkaline conditions. The effects of various reaction parameters on the extent of the yield of the resol resin, unreacted phenol content, and viscosity were investigated. Milder resol resinification conditions were required as compared to those used in conventional methods. The liquefied wood‐based resol resin was successfully applied to produce phenolic foam using appropriate combinations of foaming agents. Diisopropyl ether with a relatively higher boiling temperature was suitable for the foaming of liquefied wood‐based resol resin. Hydrochloric acid and poly(ethylene ether) of sorbitan monopalmitate were used as a catalyst and a surfactant, respectively. The obtained foams showed satisfactory densities and compressive properties, comparable to those of foams obtained from conventional resol resin. Foams with low density were obtained by the blending of liquefied wood‐based resol resin and conventional resol resin. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 468–472, 2002; DOI 10.1002/app.10018     

Pyrolysis of 1,3-butanediol as a model reaction for wood liquefaction in supercritical water

1, 3-Butanediol was pyrolyzed at 425°C in a batch reactor as a model system for liquefaction of lignocellulosic materials such as wood. The observed gas and liquid products were consistent with fragmentation, dehydration, and condensation/polymerization reaction pathways. Reaction in supercritical water altered the selectivity of the reactions to give mainly propene and formaldehyde. Dehydration and the formation of two-carbon products were suppressed by water. The conversion of 1, 3-butanediol in dilute aqueous solutions increased three to four fold when the reaction density was increased by 33%. Trace oxygen was an important inhibitor, particularly in the dilute solution, but had only a minor effect on the reaction selectivity.     

Properties of phenol‐formaldehyde resins prepared from phenol‐liquefied lignin

In this study, alkaline lignin (AL), dealkaline lignin (DAL), and lignin sulfonate (SL) were liquefied in phenol with sulfuric acid (H₂SO₄) or hydrochloric acid (HCl) as the catalyst. The phenol‐liquefied lignins were used as raw materials to prepare resol‐type phenol‐formaldehyde resins (PF) by reacting with formalin under alkaline conditions. The results show that phenol‐liquefied lignin‐based PF resins had shorter gel time at 135°C and had lower exothermic peak temperature during DSC heat‐scanning than that of normal PF resin. The thermo‐degradation of cured phenol‐liquefied lignin‐based PF resins was divided into four temperature regions, similar to the normal PF resin. When phenol‐liquefied lignin‐based PF resins were used for manufacturing plywood, most of them had the dry, warm water soaked, and repetitive boiling water soaked bonding strength fitting in the request of CNS 1349 standard for Type 1 plywood. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Initial solvation of coal with tetralin under liquefaction conditions

Secondary vitroplast, produced by treating a Liddell vitrinite concentrate with tetralin in a continuous flow, packed-bed microreactor under a nitrogen pressure of 13.8 MPa at 360, 410 and 460 °C, has been analysed by i.r. spectroscopy, gel permeation chromatography, solid state ¹³C n.m.r. and reflectance microscopy. Results showed that this intermediate in the liquefaction process had the same carbon aromaticity as the untreated vitrinite concentrate and that both its aromaticity and reflectance were independent of the temperature of formation. It was concluded that the initial solution of the vitrinite concentrate in tetralin involved no significant hydrogenation of the vitrinite.     

A scanning electron microscope study of structural changes during the liquefaction of poplar sticks by rapid aqueous thermolysis

Scanning electron microscopy shows that the liquefaction of poplar sticks (6.35 mm square cross section) by aqueous pyrolysis first involves the surface disruption of the middle lamella. The latter and cell walls then fuse, and the flowing matrix then engulfs the cells. At surface temperatures of 280°C spherical structures appear within the stick, particularly on vessel walls. Flowing matrix fills irregular cavities within the stick and gas or vapour bubbles are formed. The spherical structures are insoluble in ether, which dissolves monomeric material, but are disrupted by chloroform which dissolves oligomers. Acetone which dissolves higher molecular weight material, removes the spheres.