High and low esterification degree pectins decomposition by hydrolysis and modified Maillard reactions for furfural production

In recent years, there has been a great interest in the conversion of lignocellulosic structures to furfural. There are many technologies available for this process. Nonetheless, the present work reports for the first time the use of pectin, a non-lignocellulosic structure, for furfural production. The pectin was extracted from food industry waste derived from cactuses, orange peels and mangoes peels. The extracted pectins were analyzed by infrared spectroscopy (ATR–FTIR) in order to evaluate the degree of esterification (DE). The high DE influences in the hydrolysis reaction in the following stages: (1) hydration, it allows a fast glycosidic bond cleavage in the polysaccharide. (2) Dehydration, an intermediary step in the furfural production from galacturonic acid. The Maillard reaction herein reported not only is used in a novel way to produce furfural but also it has been modified to be performed in acidic conditions to increase the furfural production rate. From the evaluated reactions, it was found that the highest furfural production was obtained with manila mango pectin (82.6 g/L) with a DE of 51.2%. These findings demonstrate that pectins with DE below 75%, the minimum value to be considered for applications in the food and pharmaceutical industries, could be applied for the generation of furfural, a chemical platform for the production of chemicals and biofuels.     

Synthesis of C60-Furfural Adduct

Abstract

Diels-Alder cycloaddition of furfural to C₆₀ in toluene has been realised. UV-VIS, FTIR and ¹H-NMR investigations suggest that the conjugated structure of furfural was changed into a non-conjugated structure in the product.     

Robust Co3O4 nanocatalysts supported on biomass-derived porous N-doped carbon toward low-pressure hydrogenation of furfural

The catalytic conversion of biomass platform chemicals using abundant non-noble metal nanocatalysts is a challenging topic. Here, high-density cobalt oxide nanoparticles loaded on biomass-derived porous N-doped carbon (NC) was fabricated by a tandem hydrothermal pyrolysis and mild nitrate decomposition process, which is a green and cheap preparation method. The Co₃O₄ nanoparticles with the average size of 12 nm were uniformly distributed on the porous NC. The nanocomposites also possessed large surface area, high N content, good dispersibility in isopropanol, and furfural absorbability. Due to these characteristics, the novel cobalt nanocatalyst exhibited high catalytic activity for producing furfuryl alcohol, yielding 98.7% of the conversion and 97.1% of the selectivity at 160 °C for 6 h under 1 bar H₂. The control experiments implied that both direct hydrogenation and transfer hydrogenation pathways co-existed in the hydrogenation reaction. The excellent catalytic activity of Co₃O₄@NC was attributed to the cooperative effects of porous NC and Co₃O₄ nanoparticles. This approach provides a new idea to design effective high-density non-noble metal oxide nanocatalysts for hydrogenation reactions, which can make full use of sustainable natural biomass.     

高效液相色谱法测定绝缘油中糠醛含量的不确定度评定

绝缘油中的糠醛含量能够评估变压器绝缘纸的老化状况,并反映其绝缘性能.通过高效液相色谱法对绝缘油中糠醛含量进行定量分析,建立数学模型,确定测定结果的不确定度来源为糠醛标准物质、标准油液的配制、标准曲线的拟合、样品制备、回收率、测量重复性,并对测试结果进行不确定度评定.实验结果表明,绝缘油中糠醛样品浓度为1.05 mg/k...     

反应物结构对酚醛凝胶及其气凝胶的影响

为研究反应物酚与醛的结构对酚醛凝胶过程及其气凝胶结构的影响,采用不同的酚与醛制备出了多种气凝胶。研究了反应物结构对凝胶过程的影响,并通过扫描电镜和孔径分析仪等仪器详细研究了气凝胶的结构。结果表明,酚醛反应的凝胶时间受反应物的活性及位阻效应共同影响,反应体系选择不当可能导致无法凝胶。采用不同的酚-醛体系,所得气凝胶结构也...     

Correlation between the capacitor performance and pore structure of ordered mesoporous carbons

Mesoporous carbons were synthesized by organic–organic self-assembly of triblock copolymer F127 and phenolic resin oligomers composed of resorcinol–formaldehyde or resorcinol–furfural. The mesostructure control was performed by using different polymerization catalysts, ammonia and acetic acid. The effects of the aldehyde and polymerization catalyst on pore architecture of mesoporous carbons were investigated. Disordered mesostructure with poorly disconnected mesopores was formed using furfural. In contrast, when formaldehyde was used, ordered structure with mesochannels was formed. In addition, changes in mesochannel length and the degree of long-range order are found to depend on polymerization catalyst. The porous carbons with different structure were used as a model material to investigate the ion storage/transfer behavior in electrical double-layer capacitor. Electrochemical cyclic voltammetry measurements were conducted in 1 M sulfuric acid electrolyte solution. The ordered mesoporous carbons show superior capacitances and rate performance over the disordered carbons. Electrochemical impedance spectroscopy was used to assess the transport properties. The impedance data clearly demonstrated that the degree of long-range order and channel length can influence the ion transport, resulting in superior capacitive performances.     

有序中孔炭球的自组装合成及其结构控制

以间苯二酚糠醛低聚物为炭前驱体,三嵌段共聚物F127为结构导向剂,通过悬浮辅助的蒸发诱导自组装乳化成球,高温炭化后得到有序中孔炭球. 考察了乳化剂用量和搅拌速度对有序中孔炭球的粒径和表面形貌影响,嵌段共聚物F127与间苯二酚摩尔比（F127/R）及间苯二酚糠醛反应时间对有序中孔炭球的微观结构影响. 结果表明：当乳化剂用量从0.1vol%增加到2.0vol%,有序中孔炭球的粒径从400μm减小到100μm;在乳化剂用量相同时,搅拌速度从100r/min增加到600r/min, 有序中孔炭球的粒径从341μm减小到60μm;当 F127/R的比值为0.008、0.015和0.025时,分别制得三维体心立方、二维六方和无序蠕虫结构的中孔炭球.     

Influence of the copper ion on aging rate of oil-paper insulation in a power transformer

To identify the influence of copper ion on the aging rate of oil-paper insulation, accelerated thermal aging experiments on oil-paper insulation were designed and performed at two significant temperatures. A set of characteristic parameters, including dissolved gases, degree of polymerisation, furfural content, water content and acid number of oil, was tested. The experiments- results reveal that copper ion has a different influence on insulation paper and oil during the aging process of the insulation system. On the one hand, it delays the degradation of insulation paper, reducing the ratio of CO₂/CO by about 11% at 80%C and by more than 50% at 130%C. On the other hand, copper ion promotes the oxidation of oil and thus accelerates the aging rate.     

糠醛系功能高分子材料的研究进展

论述了可再生资源糠醛及其衍生物的聚合反应、聚合物的结构以及用作光电转换、光热转换、离子交换树脂、螯合树脂等功能高分子材料的发展及应用概况,并展望了糠醛系功能高分子材料开发前景。     

烧绿石型富氧相Ce2Zr2O8的Rietveld结构精修及其Raman光谱研究

采用石墨还原法成功制备了烧绿石型富氧相Ce₂Zr₂O₈, 选用缺氧型烧绿石Nd₂Zr₂O₇作为Ce₂Zr₂O₈相前驱体CeZrO_3.5的替代物与之进行结构对比分析。实验结果表明: Ce₂Zr₂O₈相中富余氧主要占据前驱体中的氧空位, 且氧离子扩散不会破坏原本有序排列的阳离子(Ce/Zr)亚点阵; 同时, Ce₂Zr₂O₈相中Zr-O 配位体由前驱体中共顶联接的八面体转变为共棱联接的立方体, 其反相畴界密度和振动光谱谱带亦较前驱体明显提高。以上结果说明Ce₂Zr₂O₈相结构处于亚稳态, 该结构特征有利于氧离子的快速吸附或释放, 这为其成为汽车尾气净化剂提供了结构上的可行性, 但也说明当An₂Zr₂O₇烧绿石在自辐照条件下向富氧相An₂Zr₂O₈发生转变时, 其抗辐照和化学稳定等性能有下降趋势。     

Eu2+在多铝酸钠体系中的发光

应用高温固相法合成了Na的多铝酸盐,并研究了Eu^2＋在体系中的发光性能．结果表明,Na_1＋xMgAl_11－xO₁₇体系在整个组成范围内保持Na的β－Al₂O₃结构不变,而对于Na_1．67－2xBa_xAl1_0．33O₁₇体系,在x＝0．30附近体系结构发生转变,x＜0．30,体系形成Na的外β－Al2O3结构的固溶体,x＞0．30,体系形成Ba的β－Al₂O₃结构的有序体;与体系组成和结构的变化相对应,Eu^2＋的发射能量和发光强度产生相应的变化,在Na的β－Al₂O₃中Eu^2＋存在高、低能两种发射中心;通过系列化研究,获得了新的组成的、具有β－Al₂O₃结构的荧光体Na_0．67Ba_0．50Mg_0．67Al_10．33O₁₇：Eu^2＋,在较低的掺杂浓度（0．05mol）下可以产生较强的发光．     

Nd2Zr2O7烧绿石A、B位晶格固化钍的结构演化及化学稳定性研究

A₂B₂O₇烧绿石以其高包容性和物理化学稳定性而成为高放废物固化体候选基材。研究通过喷雾热解-高温烧结制备了Nd₂Zr₂O₇烧绿石A、B位钍掺杂Nd_1.8Th_0.2Zr₂O₇和Nd₂Zr_1.8Th_0.2O₇固化体, 利用不同检测手段分析样品结构, 并通过MCC-1方法研究了样品化学稳定性。Nd₂Zr₂O₇烧绿石A和B位掺杂Th均能形成纯烧绿石结构, 掺杂将造成烧绿石结构中48f氧位置参数增大, 烧绿石向无序化结构转变。A位掺杂导致烧绿石AO₈六面体结构扭曲, B位掺杂导致BO₆八面体部分形变。Nd_1.8Th_0.2 Zr₂O₇和Nd₂Zr_1.8Th_0.2O₇固化体在42 d周期后Th离子浸出率在10^-5 g·m^-2·d^-1量级, 说明锕系核素Th在Nd₂Zr₂O₇的A、B位均能很好地被包容, 固化体表现出优异的物理化学性能。     

糠醛对碳钢缓蚀性能的研究

采用失重法研究了糠醛对碳钢的缓蚀性能。实验表明30 ℃，4 h条件下，在5% 的盐酸中，糠醛具有较强的缓蚀作用，与六次甲基四胺复配缓蚀效果增强。通过研究找到了糠醛在碳钢上的吸附等温式，计算出碳钢溶解的表观活化能，研究了糠醛在碳钢上的吸附机理。研究表明糠醛为混合控制型缓蚀剂。     

纳米Al_2O_3分布对Al_2O_3/PE-EVA复合材料导热性能与力学性能的影响

旨在将纳米Al2O3分散在聚乙烯(PE)和乙烯醋酸乙烯共聚物(EVA)的共混物中,构建具有选择性分布结构的局域高粒子浓度导热复合材料。采用纳米Al2O3为导热填料,以PE和EVA为基体树脂,使用熔融共混法制备了Al2O3/PE-EVA导热复合材料。利用选择性溶液萃取方法和SEM研究了PE-EVA共混物的相结构及纳米Al2O3在共混物中的分布,评价了Al2O3/PE-EVA复合材料的导热性能与力学性能。结果表明:在PE与EVA质量比为1∶1时可获得具有两相共连续结构的共混物;在两相共连续PE-EVA共混物中引入纳米Al2O3后,发现纳米Al2O3主要分布在PE相中;纳米Al2O3的分布行为及共连续结构的形成有助于提高复合材料的导热性能,在纳米Al2O3质量分数为50%时,与Al2O3/PE复合材料相比,具有选择分布和相连续结构的Al2O3/PEEVA复合材料的热导率提高了21.2%;随着纳米Al2O3质量分数的增加,Al2O3/PE-EVA复合材料的拉伸强度与Al2O3/PE复合材料的拉伸强度相近,同时由于EVA相的增韧作用,其断裂伸长率优于Al2O3/PE复合材料。     

TC11钛合金中α'相和α'相的组织演变和显微硬度

研究了TC11钛合金中α"相和α'相的显微组织转变和显微硬度。金相显微组织观察和X射线衍射分析的结果表明： 随着固溶温度的提高α"相逐渐向α'相的晶体结构转变,α相、α"相和α'相的显微组织演变规律为：α+α",α+α"+α',α+α',α'。显微硬度测试的结果表明：在935~995℃固溶后显微硬度随着温度的提高先增大后减少,在985℃固溶后显微硬度达到峰值。综合分析显微组织影响合金显微硬度的机理：在935~985℃固溶后α'片层的厚度和间距变化的幅度小,β转变组织长大缓慢,在β转变组织中先后析出α"和α'相,随着固溶温度的提高α'片层的含量随之提高产生了相变强度效果,使其显微硬度提高;在985~995℃固溶后α'片层的厚度和间距明显增大,β转变组织变粗大,α"相消失,α'相的含量降低,相变强化的效果减弱,使β转变组织的显微硬度降低。     

α,β-呋喃丙烯醛及其环氧树脂灌浆材料

针对糠醛-丙酮体系环氧灌浆材料中糠醛毒性大、易挥发及刺激性强等问题,将糠醛与含α-H的脂肪族醛通过羟醛缩合合成α,β-呋喃丙烯醛代替糠醛。研究了正丁醛、正戊醛、正庚醛等含α-H的脂肪族醛与糠醛之间的缩合反应,并对各产物性质及制备的环氧灌浆材料性能进行分析比较,优选3-呋喃基-2-乙基-丙烯醛（FEA）制备浆材,其中FE...     

SiO2@Ag@SiO2@TiO2核壳结构的制备及其光催化降解性能

光催化是一种绿色且高效的降解染料污染物的方式, 在水污染治理中应用广泛。本研究以SiO₂为核层, 依次采用氧化还原法、改进的Stöber法及水热法合成SiO₂@Ag@SiO₂@TiO₂多层核壳结构作为光催化剂用于染料污染物降解, 并探讨了硝酸银(AgNO₃)、正硅酸乙酯(TEOS)、钛酸四丁酯(TBOT)等用量对包覆效果的影响。采用不同表征手段对样品的微观形貌、物相结构、孔结构参数和光电性能进行分析表征。结果表明, 当AgNO₃、TEOS、TBOT与SiO₂的质量比为5 : 2.4 : 6 : 1, 多层核壳结构每层均达到最优包覆效果。与SiO₂@TiO₂和SiO₂@Ag@TiO₂催化剂相比较, SiO₂@Ag@SiO₂@TiO₂核壳结构的光催化剂具有更佳的光催化活性, 光照45 min可降解93%的MB溶液, 经4次循环后其光催化效率为90%。     

Insertion/extraction reactions of lithium with LiV2O4

Lithium has been inserted into, and extracted from, the spinel Li_1.0V₂O₄ both electrochemically and chemically. Electrochemical and structural data show that in the system Li_1+xV₂O₄, for 0 < x ≤ 0.5, Li⁺ ions are inserted into the interstitial octahedral sites of the A_tet[B₂]_octX₄ spinel structure. At x ≈ 0.5, Li⁺ ions in the tetrahedral A-sites are displaced into the remaining octahedral sites to yield, at x = 1, a rocksalt phase Li₂V₂O₄; the [B₂]X₄ framework is unperturbed by the lithiation process. This framework also remains intact when Li⁺ ions are removed from Li_1.0V₂O₄ to a composition Li_0.67V₂O₄. Further extraction of lithium from the structure is accompanied by migration of some vanadium ions from the B-sites to the interstitial octahedral sites of the spinel structure. This process reduces the crystal symmetry from cubic to trigonal symmetry. In Li_0.27V₂O₄ the structure resembles that of Li_0.22VO₂, obtained by delithiation of layered LiVO₂, in which the vanadium cations are distributed in a 2:1 ratio between alternate cubic-close-packed oxygen layers; in the LiV₂O₄ spinel this ratio is 3:1.     

高稳定性(EDA)(FA)2[Pb3I10]层状钙钛矿薄膜的制备与表征

为了提高钙钛矿太阳能电池在潮湿环境中的稳定性, 采用一步法, 通过在DMF中混合(EDA)I₂、(FA)I和PbI₂, 将乙二胺离子引入钙钛矿晶格, 成功制备了一种具有较高稳定性的二维片层状的钙钛矿结构薄膜。通过原位掠入射X射线衍射(GIXRD)、X射线衍射(XRD)、扫描电子显微镜(SEM)、紫外-可见吸收光谱(UV-Vis)和原子力显微镜(AFM)等方法检测分析(EDA)(FA)₂[Pb₃I₁₀]在低湿度及高湿度环境下的结构、形貌以及光学性能变化。结果表明: 制备的 (EDA)(FA)₂[Pb₃I₁₀]薄膜在相同湿度环境下比当前广泛应用于钙钛矿太阳能电池的甲胺铅碘薄膜(CH₃NH₃PbI₃)稳定性更高; 薄膜的光学带隙约为1.67 eV, 与太阳能电池最佳带隙比较接近。另外, (EDA)(FA)₂[Pb₃I₁₀]薄膜在可见光范围吸光性能较好; 薄膜的粗糙度很小, 适合制备太阳能电池, 而且, 成本较硅基太阳能电池低廉, 在分子水平较CH₃NH₃PbI₃的可调谐性更大, 使钙钛矿太阳能电池在未来大面积应用成为可能。     

多因素影响下苯乙烯-丁二烯-苯乙烯嵌段共聚物改性沥青性能分析

通过掺加不同含量糠醛抽出油、红油增塑剂与苯乙烯-丁二烯-苯乙烯嵌段共聚物(SBS)改性剂,分析其对SBS改性沥青各性能指标的影响,判断影响SBS改性沥青性能的主要因素。结果表明:改性沥青中SBS改性剂含量是提高软化点、弹性恢复的主要因素;糠醛抽出油含量增大则可明显提高其延度指标,且改善SBS改性沥青的离析程度;红油增塑剂含量增大可大幅提高SBS改性沥青的延度指标,但高温性能下降且离析严重,短期老化后指标下降幅度高于同等含量抽出油老化后指标。因此可在SBS含量确定的情况下,通过掺加适当的糠醛抽出油以改善SBS改性沥青的性能。