毛竹屑与玉米淀粉共液化产物制备聚氨酯泡沫研究

采用单因素试验设计,研究了液化剂组成、液比以及毛竹屑与淀粉的比例对液化产物理化性质、及所制备的聚氨酯泡沫材料的物理力学指标影响.结果显示当以50%乙二醇+50%碳酸亚乙酯混合物作为液化剂、添加相当于液化剂质量3%的浓硫酸为催化剂、在(150±5)℃(油浴)和常压条件下,液化150min,搅拌速度30r/min,取得本试验条件下最好的竹屑液化效果,液化产物中竹屑含量25%,残渣率3.96%,但该液化产物中天然聚合物碎片含量少,所制备的聚氨酯泡沫材料塌陷;竹屑与玉米淀粉共液化有效提高了液化产物中生物质的含量,但占液化剂质量25%竹屑+占液化剂质量125%玉米淀粉共液化产物粘度太高(8.85Pa.s);而20%竹屑+130%玉米淀粉的共液化产物与4,4′-二苯基甲烷二异氰酸酯以及各种助剂按异氰酸酯基/羟基摩尔比为1.1配合时,所制备的聚氨酯泡沫材料表观密度为33.6kg/m3、压缩强度118kPa、弹性模量6.91MPa,在周年生物降解试验中,该生物质基聚氨酯硬质泡沫失重率为12.63%.     

生物质液化制备酚醛树脂

探讨生物质液化制备酚醛树脂的液化条件、树脂化条件及其性能,分析了生物质的液化率、残渣率,生物质酚醛树脂的红外谱图、粘度、残余酚含量、复合材料拉伸性能等实验数据。研究结果表明,不同生物质对液化条件的要求各不相同,其中竹粉的最佳液化条件是以苯酚重量5%的硫酸为催化剂,反应时间为60 min;同样液化条件下,生物质液化物合成酚醛树脂的树脂化条件相近,每10 g生物质液化物盐酸催化剂添加量为0.6 mL,反应时间为30 min;在最佳实验条件下,竹粉酚醛树脂的各项综合指标最佳,相对粘度最大、液化率最高、残渣率最低、残余酚含量低,其与玻璃纤维布复合的拉伸弹性模量经向和纬向分别是1 508.56 MPa和1 161.40 MPa,大大提高了基底材料性能,使材料刚度更好;通过红外谱图研究发现,不同生物质液化物制备的酚醛树脂结构相同,说明生物质液化物可替代苯酚作为原料与甲醛进行树脂化反应,大大降低了生产成本,减少了苯酚对环境的污染。     

生物质加压液化制备甲基糖苷与酚类物质

以甲醇为液化剂、浓硫酸为催化剂,对竹子、杨木、松木和桉木四种生物质原料的加压液化进行了实验研究。结果表明,在200℃下反应30 min后,这些生物质原料可转化得到气体、固体残渣和液体生物油三种产品,且竹子的液化率最高。将竹子液化产物进一步分级处理,得到烷基多糖苷和木素解离多酚两类化学品。其中,多糖苷产品的主要成分为己糖苷类化合物,占83.38%(质量分数);多酚类产品的主要成分为4-乙基-2-甲氧基苯酚、丁香酚和3,4-二甲氧基苯酚等,占65.79%(质量分数)。同时,根据原料的物质构成和液化油的组成结构分析,提出了液化反应的机理:纤维类生物质中的纤维素和半纤维素在酸性条件下发生醇解反应生成甲基糖苷,小部分甲基糖苷进一步转化生成乙酰丙酸甲酯;原料中的木质素在降解过程中,由于酚羟基和甲氧基的供电子效应,使Cα-Caromatic键发生断裂,生成苯酚、愈创木酚等酚类物质。     

亚/超临界乙醇中羟基和氢自由基作用下的纤维素液化行为

以水杨酸为羟基自由基(HO·)捕捉剂、四氯化碳为氢自由基(H·)捕捉剂,采用间歇高压反应釜对玉米秸秆纤维素在亚/超临界乙醇中的液化行为进行了研究,通过考察自由基捕捉剂用量、反应温度和反应时间对纤维素液化行为的影响,研究亚/超临界乙醇产生的HO·和H·自由基对纤维素的液化作用。结果表明,随着水杨酸用量增加(0-4mL),HO·浓度升高,生物油收率由29.3%提高至47.9%,固体残渣收率从26.7%降低至24.3%;反应温度从250℃升高至320℃,HO·活性随之增强,生物油收率由35.9%升高至58.2%,固体残渣收率由51.8%降低至20.4%;随着四氯化碳用量由0增加为2mL时,H·浓度降低,生物油收率由24.7%降低至20.7%,固体残渣收率由54.1%增加至59.1%;反应时间从0到30min,液化作用不断增强,生物油收率从8.7%升高至28.5%,固体残渣收率由86.3%下降至60.9%;30min之后,四氯化碳对H·活性的抑制加强,导致液化作用减弱,生物油收率有所下降。实验结果表明,乙醇在亚/超临界状态下能够产生HO·和H·,且HO·和H·浓度和活性与反应条件相关,对纤维素液化产物的收率及其分布具有明显的影响。     

磺化活性炭固体酸在藻类乙醇热液化中的应用研究

采用浓硫酸磺化法制备磺化活性炭固体酸(AC-SO_3H),考察了反应温度和活性炭粒度对固体酸总酸量的影响.结果表明,反应温度越高、活性炭粒度越小,AC-SO_3H总酸量越大,最大酸量为0.878 mmol g~(-1).将该催化剂分别应用到小球藻和浒苔的乙醇热液化过程,对其催化性能进行考察.结果表明:AC-SO_3H的催化活性随其总酸量的增加而提高,最佳用量均为5%.在最优催化条件下,小球藻和浒苔液化的生物油产率分别提高了12.32%和10.33%;残渣收率分别降低了4.11%和4.49%;生物油热值分别提高了1.18和2.38 MJ kg~(-1).AC-SO_3H催化剂的加入促进了液化过程中的酯化和脱羧反应,并且可能改变了蛋白质的降解路径,抑制了美拉德反应,对生物油品质起到了改善作用.     

硫酸钙晶须催化合成三羟甲基丙烷三丙烯酸酯

以三羟甲基丙烷(TMP)、丙烯酸(AA)为原料,硫酸钙晶须为催化剂,环己烷和甲苯混合物为带水剂,合成三羟甲基丙烷三丙烯酸酯(TMPTA).考察了原料配比、催化剂用量等因素对产品酯化率的影响.结果表明:以对苯二酚和吩噻嗪做混合阻聚剂,n(AA)∶n(TMP)=3.40,硫酸钙晶须的质量分数(以三羟甲基丙烷用量为基准)为2.0%,、环己烷用量20%、甲苯用量30%;酯化反应温度为98 ℃,反应时间为5 h,在此条件下合成的三羟甲基丙烷三丙烯酸酯酯化率大于96.8%,纯度达到97.6%.     

麦草碱木质素的微波辅助液化降解

研究了微波辅助条件下液化剂、催化剂、反应温度和反应时间对麦草碱木质素进行液化降解制备生物油收率的影响,并利用红外光谱(FT-IR)、气相色谱质谱联用仪(GC-MS)和核磁共振氢谱(1H-NMR)对产物进行表征。结果表明,微波辅助下以甲醇为液化剂,硫酸铁为催化剂液化降解碱木质素可以显著缩短液化反应时间,在160℃相对较低液化温度下反应5 min,生物油的收率达到55.22%。液化降解后的木质素残渣结构变化少,表明木质素降解产物的重新聚合的几率低,碱木质素反应原料可以回收再利用以提高原料利用率。生物油主要为单酚类物质,其中,S型、G型和H型单体的含量分别为57.72%、25.28%和8.98%。核磁共振氢谱中β-O-4键和C-C键质子峰的存在说明生物油中含有部分的二聚体和低聚体酚类化合物。     

低阶煤温和液化特征分析

利用管弹反应器考察了霍林郭勒褐煤在温和条件下的液化特征,探讨了温度、溶剂、压力、气氛、催化剂对液化产物分布的影响;分别利用程序升温热解技术和红外光谱分析了液化产物中己烷不溶物的气态烃逸出规律和结构特征;利用凝胶渗透色谱、同步荧光光谱和红外光谱分析了不同反应条件下产物沥青烯和前沥青烯的结构特征。结果表明,实验条件下霍林郭勒煤的起始热解液化温度在350℃左右;随温度的升高,液化转化率增大。较高温度时(450℃)缩聚反应加剧,液化转化率开始减小;溶剂对沥青烯类产物的生成极为重要,提高反应压力和添加催化剂主要促进油气的生成;温和条件下(350、400℃)对霍林郭勒煤的临氢处理,可获得热解反应性较原煤高的液化残渣(己烷不溶物);产物沥青烯和前沥青烯的分子量在液化温度为300和350℃时为最大;随反应温度升高,沥青烯和前沥青烯的芳烃结构特征增强,烷烃结构特征减弱。     

亚/超临界乙醇液化秸秆纤维素解聚反应研究与机理初探

利用间歇式高压反应釜,在反应温度200～330 ℃、乙醇用量0～150 mL条件下,考察了亚/超临界乙醇直接液化秸秆纤维素的解聚行为,并初步探讨了其液化机理。结果表明,反应温度、乙醇用量和反应停留时间对秸秆纤维素的液化均有显著影响,反应温度由200 ℃升高至330 ℃,重油和气体收率分别增加了12.55%、28.83%;乙醇用量增加,反应压力随之升高,乙醇进入超临界状态,残渣和气体收率相比单纯热裂解分别降低11.10%和8.44%。通过GC/MS、FT-IR分析生物油组分和残渣特性,表明秸秆纤维素在亚/超临界乙醇中断键裂解,且酮类和乙酯类化合物是生物油的主要成分。     

固体酸催化合成乙酸正丁酯——推荐一个绿色化学实验

以自制固体酸Zr(SO4)2/SiO2代替浓硫酸为催化剂改进乙酸正丁酯合成实验;通过吸附吡啶的红外光谱图FT-IR表征固体酸的酸类型;采用KOH标准溶液滴定反应混合物的酸值测定反应的酯化率。结果表明,固体酸Zr(SO4)2/SiO2为Brönsted酸,其制备简单,催化合成乙酸正丁酯的酯化率高达99%,反应后处理简便,无废液排放,催化剂可重复使用;改进型实验符合绿色化学要求,并涉及无机、有机、分析及物理化学的相关内容,具有显著的综合性化学实验特征。     

Preparation and characterization of biopolyol via liquefaction of rice straw

Biopolyols were prepared by the liquefaction of rice straw under the mild condition. The optimum liquefaction effect was obtained at 5 : 1 volume ratio of PEG400 to DEG, 4 : 1 liquid–solid ratio, H₂SO₄ 3%, time 2.5 h, and reaction temperature120°C. Products were characterized by FTIR and gel permeation chromatograms (GPC) measurements. The hydroxyl value and weight-average molecular weight of the biopolyol produced based on the above optimal conditions were 260 mg KOH/g polyol and 420 g mol^–1, respectively. Biopolyol obtained is suitable for the preparation of rigid polyurethane foam. This study has certain significance for the high added value use of rice straw and reducing the production cost and improvement biodegradability of polyurethane foams.     

The study of mechanical behavior and flame retardancy of castor oil phosphate-based rigid polyurethane foam composites containing expanded graphite and triethyl phosphate

The goal of this work was the synthesis of novel flame-retarded polyurethane rigid foam with a high percentage of castor oil phosphate flame-retarded polyol (COFPL) derived from renewable castor oil. Rigid flame-retarded polyurethane foams (PUFs) filled with expandable graphite (EG) and diethyl phosphate (TEP) were fabricated by cast molding. Castor oil phosphate flame-retarded polyol was derived by glycerolysis castor oil (GCO), H₂O₂, diethyl phosphate and catalyst via a three-step synthesis. Mechanical property, morphological characterization, limiting oxygen index (LOI) and thermostability analysis of PUFs were assessed by universal tester, scanning electron microscopy (SEM), oxygen index testing apparatus, cone calorimeter and thermogravimetric analysis (TGA). It has been shown that although the content of P element is only about 3%, the fire retardant incorporated in the castor oil molecule chain increased thermal stability and LOI value of polyurethane foam can reach to 24.3% without any other flame retardant. An increase in flame retardant was accompanied by an increase in EG, TEP and the cooperation of the two. Polyurethane foams synthesized from castor oil phosphate flame-retarded polyol showed higher flame retardancy than that synthesized from GCO. The EG, in addition to the castor oil phosphate, provided excellent flame retardancy. This castor oil phosphate flame-retarded polyol with diethyl phosphate as plasticizer avoided foam destroy by EG, thus improving the mechanical properties. The flame retardancy determined with two different flame-retarded systems COFPL/EG and EG/COFPL/TEP flame-retarded systems revealed increased flame retardancy in polyurethane foams, indicating EG/COFPL or EG/COFPL/TEP systems have a synergistic effect as a common flame retardant in castor oil-based PUFs. This EG/COFPL PUF exhibited a large reduction of peak of heat release rate (PHRR) compared to EG/GCO PUF. The SEM results showed that the incorporation of COFPL and EG allowed the formation of a cohesive and dense char layer, which inhibited the transfer of heat and combustible gas and thus increased the thermal stability of PUF. The enhancement in flame retardancy will expand the application range of COFPL-based polyurethane foam materials.     

乙二醇醇解松木屑反应特征及机理分析

利用酸化的乙二醇作溶剂对松木屑进行醇解,探讨了温度和时间对醇解转化率的影响。利用热重分析、红外光谱分析、扫描电镜及X射线衍射考察了醇解残渣的性质。分别利用傅里叶变换红外光谱及色质联用分析了正己烷不溶物和可溶物中组分的分布及特征。结果表明,松木屑转化率在90 min、160℃达到最大值95.3%。松木屑中纤维素无定形区的组分和木质素发生了解离,醇解残渣的表面结构被破坏;正己烷不溶物是含有羟基、甲氧基及醚键等含氧官能团的化合物;正己烷可溶物主要由苯二甲酸酯、硬脂酸甲酯、2-甲基己酸丙酯、2-甲基丙酸、聚乙二醇及未反应的乙二醇组成。乙二醇与松木屑解离的羧酸发生酯化反应,对液相产物具有稳定作用,促进了松木屑的醇解反应;醇解过程中乙二醇自缩聚生成聚乙二醇,增大了乙二醇的消耗。     

Recycling of polyurethane wastes using different carboxylic acids via acidolysis to produce wood adhesives

This study aims to provide further understanding on the depolymerization of polyurethanes (PU) via acidolysis. Therefore, polyurethane foams scraps are chemical recycled using different dicarboxylic acids, namely succinic and phthalic dicarboxylic acids, being the reaction products identified using Fourier-transform infrared spectroscopy, nuclear magnetic resonance and gel permeation chromatography. The results obtained show that succinic acid has higher efficiency as cleavage agent, as a result, the succinic acid ensuing recovered polyol (RP) presents higher hydroxyl value and lower viscosity. Additionally, from the oxidative-induction time measurements, it is observed that the RP is considerably more thermally stable, than the petroleum-based polyol, due to the higher content of aromatic moieties. Afterwards, the RP is used as substitute of petroleum-based polyol in the production of polyurethane adhesives (PUA) and compared with conventional polyol based PUA. Due to the higher content of aromatic moieties, higher bonding strength is achieved using the RP. Overall, further understanding on the acidolysis is obtained, proving the suitability of this method for the recycling of PU.     

A novel direct synthesis of polyol from soybean oil

As the oil crisis and environment concerning deepen,the uses of renewable resources have attracted considerable attention.Polyol intended for synthesis of polyurethane polymers was prepared by a novel direct hydroxylation of soybean oil,alternative to petroleumbased process.The transformation can afford soybean oil polyol in excellent yield with a hydroxyl number up to 467.7 mg KOH/g in the presence of OsO 4 as catalyst and NMO as oxidant.The major advantages of this approach are:two hydroxyl groups can be readily added to one double bond,replacing conventional two-step methods by an epoxidation step and then a ring opening step;a wide range of hydroxyl numbers can be obtained via varying catalyst loadings;the reaction can be performed at room temperature.The chemical structure of the polyol prepared was further characterized by chemical methods(hydroxyl number and iodine number) and spectra(1 H NMR and FTIR spectroscopy),which confirmed the cleavage of the double bonds and the produce of hydroxyl groups.     

新型Brønsted-Lewis双酸位碳基固体酸的制备及其催化生物柴油的合成

以羧甲基纤维素钠（CMC）与硫酸铁螯合反应生成的螯合物为碳前驱体,以浓硫酸为磺化试剂,制备新型碳基固体酸催化剂。采用红外（FT-IR）、X射线衍射（XRD）、吡啶红外、扫描电子显微镜（SEM）、热重分析仪（TGA）、能谱仪（EDS）对催化剂进行表征。结果表明,该催化剂同时具有Brønsted和Lewis酸位点,是具有双酸位的碳基固体酸催化剂。将其应用到油酸与甲醇的酯化反应制备生物柴油体系中,考察了不同反应条件对油酸转化率的影响。在反应温度为70℃,反应时间为6h,油酸与甲醇物质的量比为1：10,催化剂用量为油酸质量7.5%条件下,油酸的转化率可达到96.8%。此外,对该催化剂的稳定性进行研究发现该催化剂有着良好的重复使用性和疏水性。     

Acid-Catalyzed Liquefaction of Bagasse in the Presence of Polyhydric Alcohol

Bagasse was subjected to a liquefaction process with polyethylene glycol/glycerol using sulfuric acid as catalyst. The effects of various liquefaction conditions, such as reaction time, liquefaction temperature, catalyst content, and liquid ratio (liquefaction solvents/bagasse), on the liquefied residue (LR) content and hydroxyl and acid numbers of liquefied products were investigated. The preferred liquefaction condition of bagasse was determined through orthogonal experiments. The results showed that the catalyst content and reaction time have a greater influence than liquid ratio and liquefaction temperature on the percentage of LR. The hydroxyl and acid numbers of the liquefied products were influenced by many factors, including liquefaction temperature, reaction time, acid content, and liquid ratio. The hydroxyl number of liquefied products decreased as the liquefaction reaction progressed, but the acid number of liquefied products increased. Based on the obtained data, the kinetics for liquefaction was modeled using the first-order reaction rate law and the apparent activation energy for the liquefaction of bagasse was estimated to be 38.30 kJ mol^?1.     

New method for lignocellulosic biomass polysaccharides conversion in butanol, an efficient route for the production of butyl glycosides from wheat straw or poplar wood

Wheat straw and poplar wood are abundant biomass which are increasingly considered as a feedstock for the production of fuels, energy and chemicals. Based on our work on optimized concentrated acid saccharification of wheat straw polysaccharides, we developed a method for the conversion of cellulose and hemicelluloses of wheat straw and poplar wood in n-butanol. Hemicelluloses and cellulose have been efficiently converted into butyl-pentosides and butyl-glucosides respectively by a one-pot decrystallization-glycosylation procedure. This process differs from published results as it is highly productive and it does not use ionic liquids for cellulose solubilisation which renders the glycosides recovery complicated, or require the use of costly acid catalyst or drastic temperature and pressure conditions. The butyl-glycosides are obtained in high yields and can be used as raw materials for the production of long tailed glycosides that are molecules of market value in the fields of detergents and cosmetics. The recovery of the sulfuric acid has also been studied and a method is proposed displaying the economic potential of the overall method and opening a new avenue for the use of wheat straw and poplar wood polysaccharides as raw materials in the surfactant industry.     

Studying the Suitability of Nineteen Lignins as Partial Polyol Replacement in Rigid Polyurethane/Polyisocyanurate Foam

In this study, nineteen unmodified lignins from various sources (hardwood, softwood, wheat straw, and corn stover) and isolation processes (kraft, soda, organosolv, sulfite, and enzymatic hydrolysis) were used to replace 30 wt.% of petroleum-based polyol in rigid polyurethane/polyisocyanurate (PUR/PIR) foam formulations. Lignin samples were characterized by measuring their ash content, hydroxyl content (Phosphorus Nuclear Magnetic Resonance Spectroscopy), impurities (Inductively Coupled Plasma), and pH. After foam formulation, properties of lignin-based foams were evaluated and compared with a control foam (with no lignin) via cell morphology, closed-cell content, compression strength, apparent density, thermal conductivity, and color analysis. Lignin-based foams passed all measured standard specifications required by ASTM International C1029-15 for type 1 rigid insulation foams, except for three foams. These three foams had poor compressive strengths, significantly larger cell sizes, darker color, lower closed-cell contents, and slower foaming times. The foam made with corn stover enzymatic hydrolysis lignin showed no significant difference from the control foam in terms of compressive strength and outperformed all other lignin-based foams due to its higher aliphatic and p-hydroxyphenyl hydroxyl contents. Lignin-based foams that passed all required performance testing were made with lignins having higher pH, potassium, sodium, calcium, magnesium, and aliphatic/p-hydroxyphenyl hydroxyl group contents than those that failed.