壳聚糖缩合呋喃甲醛螯合树脂的合成及性能研究

利用壳聚糖C2 位上活泼氨基与呋喃甲醛缩合反应 ,合成了一种新型树脂。通过L9(34 )正交试验 ,研究了缩合反应的最佳条件 :80℃乙醇中溶胀 1h ,反应 5h ,pH =4.0～ 4.5 ,反应物配比 (氨基摩尔∶醛基摩尔 )为 1∶4,缩合率达到 90 %以上。并测定了上述螯合树脂对过渡金属离子的吸附性能。     

糠醛水溶液的液-液萃取分离

糠醛是重要的化工溶剂和中间体,传统生产过程流程复杂[1],能耗高。近年已提出用不同溶剂萃取分离糠醛和水[2]。本文在前文基础上[3]选择醋酸丁酯为萃取剂测定糖醛-水-醋酸丁酯体系的LLE数据,由二组二元体系和三元体系液液平衡数据确定UNIQUAC模型中三对模型参数,并采用UNIQUAC模型模拟计算糖醛水溶液萃取分离结果,以便为错流和逆流萃取试验提供依据。1　实验部分糠醛水溶液和醋酸丁酯加入液液平衡釜[4],磁力搅拌器搅拌30分钟,待温度稳定后,静置40分钟,取上相和下相分析。平衡釜采用CS501型超级恒温水浴控温,平衡结果由SP-6800…     

Efficient Extraction of Fermentation Inhibitors by Means of Green Hydrophobic Deep Eutectic Solvents

The methods for hydrogen yield efficiency improvements, the gaseous stream purification in gaseous biofuels generation, and the biomass pretreatment are considered as the main trends in research devoted to gaseous biofuel production. The environmental aspect related to the liquid stream purification arises. Moreover, the management of post-fermentation broth with the application of various biorefining techniques gains importance. Chemical compounds occurring in the exhausted liquid phase after biomass pretreatment and subsequent dark and photo fermentation processes are considered as value-added by products. The most valuable are furfural (FF), 5-hydroxymethylfurfural (HMF), and levulinic acid (LA). Enriching their solutions can be carried with the application of liquid–liquid extraction with the use of a suitable solvent. In these studies, hydrophobic deep eutectic solvents (DESs) were tested as extractants. The screening of 56 DESs was carried out using the Conductor-like Screening Model for Real Solvents (COSMO-RS). DESs which exposed the highest inhibitory effect on fermentation and negligible water solubility were prepared. The LA, FF, and HMF were analyzed using FT-IR and NMR spectroscopy. In addition, the basic physicochemical properties of DES were carefully studied. In the second part of the paper, deep eutectic solvents were used for the extraction of FF, LA, and HMF from post-fermentation broth (PFB). The main extraction parameters, i.e., temperature, pH, and DES: PFB volume ratio (V_DES:V_PFB), were optimized by means of a Box–Behnken design model. Two approaches have been proposed for extraction process. In the first approach, DES was used as a solvent. In the second, one of the DES components was added to the sample, and DES was generated in situ. To enhance the post-fermentation broth management, optimization of the parameters promoting HMF, FF, and LA extraction was carried under real conditions. Moreover, the antimicrobial effect of the extraction of FF, HMF, and LA was investigated to define the possibility of simultaneous separation of microbial parts and denatured peptides via precipitation.     

生物基平台化合物催化转化制备糠醇

糠醇(FOL)作为一种重要且多用途的有机化工原料,可以有效地转化为各种高价值的化学品,如糠醛树脂、脲醛树脂、酚醛树脂、果酸、增塑剂和火箭燃料等。以糠醛(FAL)、木糖和果糖为原料经催化加氢制备FOL的绿色生产工艺,具有良好的应用前景和研究价值。本文系统总结了近年来国内外以FAL、木糖、果糖为原料制备FOL的研究现状,从催化剂类型、催化效率和催化机理等方面对制备FOL的催化剂进行了总结,并在此基础上对催化加氢制备FOL的发展趋势进行了展望,为开发更为新型、高效、绿色、稳定的催化剂体系提供理论指导和有益借鉴。     

制备溶剂对NiCoB非晶态合金催化剂结构及糠醛加氢性能的影响

采用化学还原法在不同单一和复配溶剂体系中制备了一系列NiCoB非晶态合金催化剂,对其液相糠醛加氢性能进行了考察,并采用N_2吸附-脱附等温线、ICP、FE-SEM、HRTEM、XRD、XPS等手段进行了表征。结果表明,在相同反应条件下,制备溶剂的表面张力、黏度、极性大小和溶解度常数等对NiCoB非晶态合金催化剂的组成、形貌和结构及其糠醛加氢反应性能均产生重要影响。由甲醇/乙二醇复配溶剂(MEG,体积比1∶1)制备的NiCoB-MEG催化剂具有最理想的糠醛液相加氢制糠醇性能,糠醛转化率达到96.4%,糠醇选择性达到83.49%,这可归因于甲醇和乙二醇之间的协同作用促进了金属组分的分散和还原。     

焙烧温度对CuMgAl催化剂催化糠醛气相加氢制糠醇性能的影响

采用分步沉淀过程制得质量比m(CuO)∶m(MgO)∶m(Al_2O_3)为25∶26∶49的CuMgAl类水滑石前驱体,经过不同温度焙烧制得CuMgAl-t催化剂。通过BET、热重、XRD、H_2-TPR和CO_2-TPD对催化剂进行表征,在固定床中考察CuMgAl-t催化剂催化糠醛气相加氢制糠醇的性能。结果表明,焙烧温度影响催化剂活性、稳定性及对产物的选择性,低温焙烧的催化剂经还原后可获得较多活性中心,高温焙烧的催化剂表面具有更多的碱性位,CuMgAl催化剂经450℃焙烧表面存在适宜的活性中心和碱性位。在常压、反应温度180℃、氢醛物质的量比5∶1、糠醛体积空速0.3h~(-1)的条件下,CuMgAl-450催化剂上糠醛的转化率和糠醇的选择性分别达到98.64%和97.66%。     

Pd/Cu(111)双金属表面催化糠醛脱碳及加氢的反应机理

采用密度泛函理论(DFT)研究糠醛在最稳定Pd/Cu(111)双金属表面上的吸附构型和糠醛脱碳及加氢的反应机理。结果表明,当糠醛初始吸附于O_3-Pd-top、O_7-Cu-hcp位时,吸附构型最稳定,其吸附能为73.4 kJ/mol。糠醛在Pd/Cu(111)双金属表面上更易发生脱碳反应。对于糠醛脱碳反应,所需活化能较低,各个基元反应均为放热反应,糠醛更易先失去支链上的H形成(C_4H_3O)CO,然后中间体脱碳加氢得到呋喃,其中,C_4H_3O加氢生成呋喃所需活化能(72.6 kJ/mol)最高,是反应的控速步骤。对于加氢反应,糠醛与首个氢原子的反应需要最大的活化能(290.4 kJ/mol),是反应的限速步骤。     

Determination of furfural in beers,vinegars and infant formulas by solid-phase microextraction and gas chromatography/mass spectrometry

The solid-phase microextraction (SPME) technique with on-fibre derivatisation was evaluated for the analysis of furfural in infant formulas, beers, and vinegars. The poly(dimethylsiloxane)/divinylbenzene (PDMS/DVB) fibre was used and O-2,3,4,5,6-(pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA) was first loaded onto the fibre. Food sample of 2?mL was then placed in a 4?mL PTFE-capped glass vial. Headspace extraction by the SPME fibre was performed at 80°C for 20?min under 1100?rpm magnetic stirring with the addition of 40% sodium chloride. Afterwards, the SPME fibre was directly desorbed at the injection port of a gas chromatography/mass spectrometer (GC/MS), followed by the analysis of derivatives formed on-fibre. To avoid matrix interferences, standard addition method was performed. The adsorption-time profiles were examined. The precision, recovery and method detection limits (MDLs) were evaluated with spiked food samples. The relative standard deviations from different spiked samples were all less than 5% and the recoveries were 100?±?5%. With 2?mL of food sample, MDLs were in the range of 3.09?～?14.05?µg?L^?1. Compared with other techniques, the study shown here provided a simple, fast and reliable method for the analysis of furfural in food samples.     

Metal-free dehydration of glucose to 5-(hydroxymethyl)furfural in ionic liquids with boric acid as a promoter

The dehydration of glucose and other hexose carbohydrates to 5-(hydroxymethyl)furfural (HMF) was investigated in imidazolium-based ionic liquids with boric acid as a promoter. A yield of up to 42% from glucose and as much as 66% from sucrose was obtained. The yield of HMF decreased as the concentration of boric acid exceeded one equivalent, most likely as a consequence of stronger fructose-borate chelate complexes being formed. Computational modeling with DFT calculations confirmed that the formation of 1:1 glucose-borate complexes facilitated the conversion pathway from glucose to fructose. Deuterium-labeling studies elucidated that the isomerization proceeded via an ene-diol mechanism, which is different to that of the enzyme-catalyzed isomerization of glucose to fructose. The introduced non-metal system containing boric acid provides a new direction in the search for catalyst systems allowing efficient HMF formation from biorenewable sources.