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以磺酸功能化咪唑离子液体为催化剂,以3-羟基丙酸甲酯为原料,采用自身酯交换法合成了具有生物可降解性能的聚羟基脂肪酸酯.系统考察了离子液体种类、反应温度以及聚合反应时间对反应性能的影响,同时采用红外、核磁、热分析等手段对产物进行表征.研究结果表明:阴离子为CF3SO-3的磺酸功能化离子液体在120℃的低温下催化聚合反应所得聚酯Mw可达10 159,收率82.1%;通过水洗方法可有效去除产物中的离子液体催化剂,从而避免催化剂污染产物. 相似文献
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磷钨钒杂多酸相转移催化剂的制备及其深度氧化脱硫性能 《燃料化学学报》2019,47(11):1337-1345
以钒原子取代的Keggin型磷钨杂多酸与不同的季铵类阳离子表面活性剂反应合成了一系列磷钨钒杂多酸相转移催化剂,采用红外和X射线衍射对催化剂进行了表征。以H_2O_2为氧化剂,对模型柴油的氧化脱硫反应进行了研究,考察了季胺类表面活性剂种类、不同季胺盐含量、催化剂用量、氧硫比、反应温度等参数对反应的影响。结果表明,所制备的杂多酸相转移催化剂保留有杂多酸阴离子和季铵盐阳离子的结构特征。[(C_(16)H_(33)(CH_3)_3) N]_3H[PW_(11)VO_(40)]催化剂具有最佳的氧化脱硫性能和重复使用性能,在n(催化剂)/n(模型柴油)=1∶80,n(H_2O_2)/n(模型柴油)=8∶1,反应温度50℃,反应时间3 h的反应条件下,二苯并噻吩的转化率可达到100%;催化剂重复使用五次后,转化率为99.7%。反应过程中,该催化剂与反应物形成微乳体系,如同一个均相混合物,而反应结束体系静置一段时间后,催化剂和产物又形成两相,通过离心法就可以快速分离和回收催化剂。 相似文献
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研究了几种磺酸功能化离子液体催化纤维素在生物丁醇中转化为乙酰丙酸丁酯的性能. 系统考察了催化剂的酸强度, 用量, 反应温度, 时间和溶剂对纤维素转化效率和产物分布规律的影响. 实验结果表明酸度最强的磺酸功能化离子液体1-(4-磺酸丁基)-3-甲基咪唑硫酸氢盐([C4H8SO3Hmim]HSO4)能够有效地催化纤维素转化为乙酰丙酸丁酯, 且在优化的反应条件下纤维素的转化率高达98.4%, 乙酰丙酸丁酯的产率为31.1%, 同时共生产物甲酸丁酯、水溶性产物和生物油的产率分别为33.4%、20.6%和23.8%. 该催化体系具有一定的耐水性能, 水的添加量为0.2 mL时并不会严重影响纤维素的转化率. 此外, 酸性离子液体催化剂还表现出了良好的重复使用性能, 使用六次后仍然保持较高的活性. 相似文献
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采用溶胶凝胶法制备了一系列硅胶负载型离子液体催化剂(IL/sg),并成功应用于甲醛与苯乙烯及其衍生物的Prins反应中.利用红外光谱(FT-IR)、元素分析(EA)和氮气吸附-脱附等对催化剂结构进行了表征.研究表明,磺酸功能化离子液体1-甲基-3-丁磺酸基咪唑硫酸氢盐固载得到的负载型催化剂(Bs MIm HSO4/sg)表现出最佳的催化活性.在催化剂投料量为烯烃的3%,甲醛与烯烃摩尔比为4∶1,80℃下反应8 h,苯乙烯转化率达到了100%,产物选择性为90%.催化剂经简单的过滤分离后重复使用5次,仍保持良好的催化活性.此外,该催化体系具有较好的底物适用性. 相似文献
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采用溶胶-凝胶法将杂多酸功能化离子液体bmim-PW12(1)固载到硅胶上制得硅胶固载杂多酸功能化离子液体催化剂bmim-PW12/SiO2[2-x(x=5,15,25,35,50)],采用TG-DTG,FT-IR,N2低温吸附脱附,XRD和正丁胺电位滴定等方法表征2的结构、织构性能和酸性。结果表明,2-x保持了1的Keggin结构,且1被较好地固载在硅胶上;2-x具有大的比表面积和强酸性。用7%的2-35催化乙酸与正丁醇的酯化反应,收率88.5%,且2-35重复使用5次后收率仍可达到75.4%。 相似文献
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合成并表征了4种具有Brnsted酸性的磺酸功能化咪唑类离子液体催化剂,考察了其在催化苯酚、甲醛合成双酚F反应中的催化活性.结果表明磺酸功能化双核离子液体双-(3-磺酸丙基-1-咪唑)亚丁基硫酸氢盐([DPSIM][HSO4]2)不仅催化活性最佳,还提高了4,4’-双酚F异构体的含量.以[DPSIM][HSO4]2为催化剂,在苯酚与甲醛摩尔比30∶1、离子液体催化剂质量浓度6.8%、反应温度90℃、反应时间60 min的优化条件下,双酚F收率可达94.1%,同时提出了其催化合成双酚F的反应机理.该离子液体催化剂腐蚀性低,易分离回收,在重复使用6次后,双酚F收率仍在70%以上. 相似文献
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The new inorganic–organic hybrids based on SO3H‐functionalized ionic liquids (ILs) and Keggin‐type heteropoly acids (H3PW12O40, H3PMo12O40, and H4SiW12O40; HPAs) are prepared and characterized by FT‐IR, NMR, XRD, CV, SEM/EDX, ICP‐OES, BJH and UV. Different molecular structures according to the different inorganic part were also proved. Potentiometric titration showed a good relationship between catalytic activity and acidity of the catalysts. Electrochemical aspects showed electron transfer ability of the compounds. For understanding catalytic activities of the HPA‐IL hybrids in N‐formylation reaction, effect of catalyst composition, substrate, and reaction conditions were studied. The best SO3H‐functionalized ionic liquid catalyst was readily recovered and reused for four runs. Easy preparation of the catalyst, simple and easy work‐up, mild reaction conditions, low cost, excellent yields and short reaction times are the key features of this work. 相似文献
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A series of insoluble salts of Keggin heteropoly compounds were prepared and used as catalysts for the Mannich-type reaction of benzaldehyde, aniline, and cyclohexanone in water. Among them, Cs2.5H0.5PW12O40 showed excellent catalytic activity. Effects of surfactant, catalyst loading and temperature were studied to introduce the best reaction condition. The optimized reaction conditions were extended to Mannich reaction of various aldehydes, ketones, and amines in water. This rapid procedure afforded structurally divers β-amino ketones with major anti diastereoselectivity. Additionally, four new compounds were reported. The catalyst was recovered and reused for subsequent runs. 相似文献
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Timofeeva M. N. Matrosova M. M. Maksimov G. M. Likholobov V. A. Golovin A. V. Maksimovskaya R. I. Paukshtis E. A. 《Kinetics and Catalysis》2001,42(6):791-795
The esterification reaction of n-butanol with acetic acid ([BuOH] : [HOAc] = 1 : 15 mol/mol; 55°C, 5% H2O) was studied in the presence of tungsten heteropoly acids of the Keggin (H3PW12O40, H4SiW12O40, H5PW11TiO40, H5PW11ZrO40, and H3PW11ThO39) and Dawson structure (-H6P2W18O62, H6P2W21O71(H2O)3, H6As2W21O69(H2O), and H21B3W39O132). The reaction orders with respect to H6P2W21O71(H2O)3, H3PW12O40, and H6P2W18O69are equal to 0.78, 1.00, and 0.97, respectively. It was found that the reaction rate depends on the acidity, as well as on the structure and composition of heteropoly acids. The H21B3W39O132heteropoly acid is most active, whereas the Keggin-structure heteropoly acids exhibit the lowest activities. Of the Keggin structure heteropoly acids, H5PW11ZrO40exhibits the highest activity because of the presence of a Lewis acid site in its structure. 相似文献
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Bamoharram Fatemeh F Roshani Mina Heravi Majid M Mahdavi Masoumeh Javid Ali Emampour Jalal Sh 《中国化学》2010,28(6):974-976
Isoxazolo[5,4‐d]pyrimidine‐4,6(5H,7H)diones 2a – 2f have been synthesized from the reaction of ethyl 5‐amino‐3‐methyl‐4‐isoxazole carboxylate ( 1 ) with aryl isocyanates in the presence of Keggin heteropolyacid H3[PW12O40] as a green solid acid catalyst at room temperature in a one‐pot process in good yields. 相似文献
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1-Butyl-3-methylimidazolium dodecatungstophosphate catalyst ([bmim]3PW12O40) with high water tolerance was prepared from 1-butyl-3-methylimidazolium bromide ([bmim]Br) and phosphotungstic acid (H3PW12O40). The catalyst was characterized by means of Fourier transform infrared spectroscopy, thermogravimetry-differential scanning
calorimetry, n-BuNH2 potentiometric titration, elemental analysis and so on. Its catalytic activity for esterification of ethanol and acetic acid
to ethyl acetate was measured. The results show that there were three crystal-water molecules in the [bmim]3PW12O40 catalyst, and it preserved the primary Keggin structure and acid strength of H3PW12O40. The acid amount of [bmim]3PW12O40 catalyst was less than that of H3PW12O40. The [bmim]3PW12O40 catalyst exhibited higher catalytic activity and reusability in the esterification of ethanol and acetic acid to ethyl acetate.
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Translated from Chinese Journal of Catalysis, 2008, 29(7) (in Chinese) 相似文献
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Bingtong Wang Zongbin Zhang Xinyu Zhang Shixin Sun Lin Wu Rong Xing 《Chemical Papers》2018,72(3):643-649
A simple, efficient, and eco-friendly catalytic system for the oxidation of cyclohexene to adipic acid with H2O2 catalyzed by H2WO4 in Brønsted acidic ionic liquids under solvent-free conditions has been developed. Reaction conditions such as the catalysts, the types of anions and cations for Brønsted acidic ionic liquids, reaction temperature, and the amount of hydrogen peroxide, were investigated. Moreover, the Hammett acidity functions (H 0) of Brønsted acidic ionic liquids were determined using UV–visible spectrophotometry. The optimum reaction condition identified was n(H2WO4):n(Brønsted acidic ionic liquids):n(cyclohexene):n(H2O2) = 0.02:0.02:1:4.4, and the yield of adipic acid was 96% under the reaction scale of 10 mmol. The catalytic system can be easily recovered and reused for four reaction runs without significant loss of catalytic activity. Simple operation of the catalyst system and avoidance of the emission of nitrous oxide are the benefits of this work. 相似文献
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M. Sc. Sven Herrmann M. Sc. Monika Kostrzewa Prof. Dr. Andreas Wierschem Prof. Dr. Carsten Streb 《Angewandte Chemie (International ed. in English)》2014,53(49):13596-13599
Corrosion is a global problem for any metallic structure or material. Herein we show how metals can easily be protected against acid corrosion using hydrophobic polyoxometalate‐based ionic liquids (POM‐ILs). Copper metal disks were coated with room‐temperature POM‐ILs composed of transition‐metal functionalized Keggin anions [SiW11O39TM(H2O)]n? (TM=CuII, FeIII) and quaternary alkylammonium cations (CnH2 n+1)4N+ (n=7–8). The corrosion resistance against acetic acid vapors and simulated “acid rain” was significantly improved compared with commercial ionic liquids or solid polyoxometalate coatings. Mechanical damage to the POM‐IL coating is self‐repaired in less than one minute with full retention of the acid protection properties. The coating can easily be removed and recovered by rinsing with organic solvents. 相似文献
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Juan Tian Jianghua Wang Shun Zhao Caiyun Jiang Xia Zhang Xiaohong Wang 《Cellulose (London, England)》2010,17(3):587-594
The potential of heteropoly acid H3PW12O40 to catalyze the hydrolysis of cellulose to glucose under hydrothermal conditions was explored. This technology could contribute to sustainable societies in the future by using cellulose biomass. A study to optimize the reaction conditions, such as the amount of catalyst, reaction time, temperature, and the amount of cellulose used, was performed. A remarkably high yield of glucose (50.5%) and selectivity higher than 90% at 453 K for 2 h with a mass ratio of cellulose to H3PW12O40 of 0.42 were achieved. This was attributed to the high hydrothermal stability and the excellent catalytic properties, such as the strong Brønsted acid sites. This homogeneous catalyst can be recycled for reuse by extraction with diethyl ether. The results illustrate that H3PW12O40 is an environmentally benign acid catalyst for the hydrolysis of cellulose. 相似文献
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Nano-porous Composites Based on Heteropolyacid Functionalized Ionic Liquid: Synthesis,Characterization, and Catalytic Performance in Esterification 下载免费PDF全文
Functionalized ionic liquid samples (bmim-PW12) were synthesized by 1-butyl-3-methyl-imidazolium bromide (bmimBr) and 12-phosphotungstic heteropolyacid (PW12). The sam-ples were annealed at 100-450 oC and were characterized by Fourier transform infrared spec-troscopy, X-ray diffraction, scanning electron microscope, thermal gravity-DTG, brunauer emmett teller, and NH3-temperature programmed desorption. The results showed that the bmim-PW12 samples were crystal and maintained intact Keggin structure. The organic parts of those samples were partly decomposed at a temperature more than 350 oC. The sample annealed at 400 oC exhibited nano-porous structure, strong acidity, and excellent catalytic activity on the esterification of n-butanol with acetic acid. The higher ester yield was ob-tained when the mass ratio of catalyst over the reactants amount was 5% for bmim-PW12 catalyst annealed at 400 oC. 相似文献
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Approaches to increase the efficiency of Pt/C–heteropoly acid catalyst in a liquid-phase oxidation of cyclohexane using an O2–H2 mixture were studied. It was shown that small additives of ionic liquid (BMImBr, Bu4NBr, or Bu4NHSO4) significantly improve the catalytic effect of the Pt/C–H3PMo12O40–CH3CN system at 35°C, by slowing the rate of side reactions resulting in water formation, increasing the rate of oxygenate formation, and inhibiting their secondary oxidation reactions. The efficiency of H2 consumption increases from 2 to 18–25%, while the selectivity of cyclohexane conversion is 92–98%. The substitution of one or two Mo(VI) ions by V(V) in the structure of the heteropoly acid decreases these parameters. In the presence of Bu4NHSO4, a Pt/C catalyst can be used many times. During the reaction, the heteropoly acid present in the solution is in a reduced state under the action of the reaction medium and undergoes reversible redox transformations. The nature of the catalytic action of the studied system is explained from the viewpoint of the effect of ionic liquids on the properties of a Pt/C catalyst in activating O2, heteropoly molybdate chemistry, and the known mechanisms of the peroxide oxidation of hydrocarbons. 相似文献