Synthesis of propylene carbonate from urea and 1,2-propanediol

The production of propylene carbonate(PC)from urea and 1,2-propanediol(PG)was investigated in a batch process.The catalytic performances of zinc chloride and magnesium chloride were investigated for this reaction system.The influences of various operation conditions on the PC yield were explored.In this work,MgCl_2 and ZnCl_2 showed the excellent catalytic activity toward PC synthesis,and the yields of propylene carbonate reached 96.5%and 92.4%,respectively.The optimum reaction conditions were as follows...     

KOH/4A分子筛催化剂对环氧丙烷、二氧化碳和甲醇合成碳酸二甲酯反应的催化性能

 首次开发出对环氧丙烷、二氧化碳和甲醇合成碳酸二甲酯反应具有较高活性和稳定性的KOH/4A分子筛固体催化剂,考察了反应温度和催化剂活性组分KOH的负载量等因素对催化剂性能的影响. 在优化的实验条件下,环氧丙烷可以完全转化,碳酸二甲酯的收率为168%. 从实验结果推测,产物碳酸二甲酯是由环氧丙烷和二氧化碳加成生成碳酸丙烯酯,然后与甲醇发生酯交换反应生成的,甲醇对环氧丙烷和二氧化碳合成碳酸丙烯酯反应具有助催化作用.     

MCF固载离子液体催化CO2合成碳酸丙烯酯的研究

通过原位合成法将[(EtO)3SiPMIm]Cl固载在MCF材料上,制得MCF固载化离子液体催化剂[(EtO)3Si PMIm]Cl/MCF。用N2吸附-脱附、TEM和FT-IR等手段表征催化剂,并考察其在CO2与环氧丙烷(PO)环加成合成碳酸丙烯酯(PC)反应中的催化性能。结果表明,嫁接等量离子液体后,MCF固载化离子液体催化剂体系对CO2环加成合成PC反应的催化活性高于SBA-15催化剂体系。在2.5MPa、140℃反应条件下,PO的转化率高达85.4%,且催化剂具有良好的循环使用性。     

甲醇和碳酸丙烯酯合成碳酸二甲酯的研究

采用浸渍法以ZrO2为载体，以碱金属氢氧化物和碳酸盐为前驱体制备了不同的固体碱催化剂，在温和反应条件下考察了催化剂的酯交换扳应性能，并通过BET、XRD和CO2－TPD等方法对催化剂进行了表征，结果表明：Na2CO3负载到不同载体上，其催化性能明显不同，Na2CO3/ZrO2催化剂获得了较高的酯交换活性。载体的比表面和孔结构与催化剂的反应活性无一定的依存关系。而催化剂表面的酸碱性是影响酯交换活性的重要因素。     

Dimethyl carbonate synthesis via transesterification catalyzed by quaternary ammonium salt functionalized chitosan

A quaternary ammonium salt covalently linked to chitosan was first used as a catalyst for dimethyl carbonate （DMC） synthesis by the transesterification of propylene carbonate （PC） with methanol. The effects of various reaction variables like reaction time, temperature and pressure on the catalytic performance were also investigated. 54% DMC yield and 71% PC conversion were obtained under the optimal reaction conditions. Notably, the catalyst was able to be reused with retention of high catalytic activity and selectivity. Consequently, the process presented here has great potential for industrial application due to its advantages such as stability, easy preparation from renewable biopolymer, and simple separation from products.     

Synthesis of dimethyl carbonate and propylene glycol from transesterification of propylene carbonate and methanol using quaternary ammonium salt catalysts

Summary The synthesis of dimethyl carbonate (DMC) was investigated through the transesterification of propylene carbonate (PC) with methanol using quaternary ammonium salt catalysts. The reaction was carried out in an autoclave at 120-140 oC under carbon dioxide pressure of 250-400 psig. The main by-product was propylene glycol. The quaternary salts of larger alkyl group and more nucleophilic counter anion exhibited higher catalytic activity. Kinetic studies were also performed to better understand the reaction mechanism. Quaternary ammonium chlorides immobilized on polystyrene supports were also tested for their possible uses as heterogeneous catalysts.     

Catalytic asymmetric addition of carbon dioxide to propylene oxide with unprecedented enantioselectivity

New chiral catalyst systems were developed for the reaction of carbon dioxide with propylene oxide (PO) at atmospheric pressure to generate enantiomerically enriched propylene carbonate (PC). The best selectivity was achieved with a Co(III)(salen)-trifluoroacetyl complex and bis(triphenylphosphoranylidene)ammonium fluoride (PPN+F-) as catalysts, affording PC in 40% yield and 83% ee (selectivity factor = 19). In addition, PC was prepared for the first time by kinetic resolution of PO with tetrabutylammonium methyl carbonate (TBAMC, nBu4N+ (-)OOCOMe). With TBAMC as "activated CO2", up to 71% ee was obtained.     

Dawson结构杂多酸盐催化合成碳酸丙烯酯

碳酸丙烯酯(PC)是一种性能优良的高沸点、高极性的有机溶剂,在有机合成、化妆品、电池电解质和脱碳溶剂等领域中具有重要应用.     

Double metal cyanide catalyst prepared using H3Co(CN)6 for high carbonate fraction and molecular weight control in carbon dioxide/propylene oxide copolymerization

Simple mixing of H₃Co(CN)₆ and ZnCl₂ in methanol resulted in precipitates of [ZnCl]⁺₂[HCo(CN)₆]^2?, constituting a new type of double metal cyanide (DMC) catalyst exhibiting a high performance in carbon dioxide (CO₂)/propylene oxide (PO) copolymerization. High‐molecular‐weight poly(propylene carbonate‐co‐propylene oxide)s [poly(PC‐co‐PO)s] (M_n～40,000) were consistently obtained with high carbonate fractions (～60 mol %) and a high selectivity (>95%) with the new type of DMC catalyst. Conventional preparation of the DMC catalyst using K₃Co(CN)₆ and ZnCl₂ required removing KCl through thorough washing and resulted in lower carbonate fractions (10–40 mol %), which depended on the washing conditions. Feeding hydrophobic diols such as 1,10‐decanediol as chain transfer agent preserved the high carbonate fraction (～60%) and enabled precise control of the molecular weight, including preparation of a low‐molecular‐weight poly(PC‐co‐PO)‐diol (M_n ～2000), which was a flowing viscous liquid with a low T_g (?30 °C) suitable for polyurethane applications. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4811–4818     

Synthesis of propylene carbonate from urea and 1,2-propylene glycol over ZnO/NaY catalyst

Propylene carbonate (PC) was produced from 1,2-propylene glycol (1,2-PG) and urea in a continuous-flow fixed bed reactor over heterogeneous ZnO catalyst supported on NaY. Among different ZnO loadings of ZnO/NaY catalysts, 5 wt% ZnO loadings of ZnO/NaY showed the highest activity. Characterization and reaction results indicated that the catalysts with a balanced strength of acid and base sites performed well for the synthesis of propylene carbonate from urea and 1,2-PG.     

双金属氰化物催化二氧化碳与环氧丙烷聚合

研究了双金属氰化配合物(DMC)催化剂催化二氧化碳(CO2)与环氧丙烷(PO)的共聚及PO的均聚反应,考察了DMC催化剂的诱导现象。结果表明,共聚时DMC催化的诱导期比均聚短,尤其是在低CO2压力(1.0MPa)下更明显,诱导期由均聚时的45min缩短为共聚时的15min。共聚时诱导期随CO2压力升高而增加,当反应压力由1.0MPa升高至7.0MPa时,诱导期由15min增至40min。PO与CO2共聚时的引发现象不同于PO均聚:共聚引发时温度和压力突然异常升高并迅速降低至引发前的状态,而均聚引发时温度突然升高后逐渐下降。由此可知CO2能促进DMC催化剂的活化。     

Polarity Effects of Propylene Carbonate on Breakdown Strength in Microsecond Range

We investigate the polarity effects of the propylene carbonate on the breakdown voltage using the needle-plate electrodes with gaps of 0.5, 1.0, and 2.0 mm. The devices used in this study involve a compact capacitive-energy-storage pulse power source with charging time varying from 5 ms to 20 ms and a test cell with the needle-plate electrodes. The breakdown voltage is recorded by a digital oscilloscope for each gap. The results of these three groups indicate that the positive breakdown voltage is higher than the negative one and the breakdown voltage of the PC increases with the ascending electrode gap. In addition, a simulation isconducted to support this experiment. Some explanations about the polarity effect of the PC are also given.     

A Vibrational Spectroscopic Study of Ion Solvation in Lithium Perchlorate/Propylene Carbonate Electrolyte

Abstract

The infrared (IR) and Raman spectra of propylene carbonate (PC) containing various concentrations of LiClO₄ have been measured and analyzed. The difference in spectra of PC with and without LiClO₄ was attributed to the interaction of the PC molecules and lithium ions. This interaction occurs mainly on the carbonyl oxygen atom of the PC molecule. The ring deformation, symmetric ring deformation, carbonyl stretching and stretching of ring oxygens for PC are sensitive to this interaction. The solvation number of Li⁺ is also calculated. On the other hand, the structure of the ClO^? ₄ is also affected by PC molecule, forming the solvent separated ion pairs.     

稀土三元催化剂催化二氧化碳/环氧丙烷/环氧环己烷的三元共聚合研究

在稀土三元催化剂(三氯乙酸稀土配合物/二乙基锌/甘油)催化下实现了二氧化碳、环氧丙烷及环氧环己烷的三元共聚合.该催化剂对二氧化碳与环氧环己烷共聚的催化活性比对二氧化碳与环氧丙烷共聚的高.增加反应单体中环氧环己烷的比例可提高共聚物中环己撑碳酸酯的含量,大幅度改善共聚物的耐热性.     

含1,2-亚乙基单元的双酚A聚碳酸酯非光气法合成和表征

以双酚A(BPA),碳酸乙二酯(EC)和碳酸二甲酯(DMC)为原料,制备双酚A二元醇(Ⅰ)和双酚A碳酸酯(Ⅱ),并用红外光谱与核磁共振波谱对其结构进行表征.通过Ⅰ与Ⅱ的共缩聚反应及Ⅱ的自聚实现了主链中含有—CH2CH2—单元的双酚A型聚碳酸酯(PC)的非光气法合成,用凝胶渗透色谱法(GPC)和TGA-DSC对PC的分子量和热性质进行分析.结果表明,Ⅱ在240℃自聚6h后产物的Mn可达17.6×103,主链中—CH2CH2—单元的引入,可以降低聚合物的Tg,提高其结晶性,所得聚合物具有良好的热稳定性.     

The effects of substituting groups in cyclic carbonates for stable SEI formation on graphite anode of lithium batteries

Monofluoropropylene carbonate (MFPC) and trifluoropropylene carbonate (TFPC) with a monofluoromethyl (or trifluoromethyl) replacing the methyl group in propylene carbonate (PC) as well as EC-CH₂CH₂Si(CH₃)₂OSi(CH₃)₃ (Si-A) and EC-CH₂CH₂Si(CH₃)₃ (Si-B) have been synthesized. The charge–discharge studies in a Li/MCMB (mesocarbon microbeads) cell using electrolyte containing these compounds show that the solid electrolyte interphase (SEI) formation capability of MFPC/DMC (dimethyl carbonate) and TFPC/DMC are about the same as ethylene carbonate (EC)/DMC, and TFPC/PC/DMC is better than that of EC/PC/DMC, while MFPC/PC/DMC is poorer than the EC/PC/DMC. The superior SEI formation capability of TFPC could be attributed to the strong electron withdrawing group of CF₃, which promote the “ring-opening” reaction. In contrast, the electron donating group CH₃ in the PC structure may demote the “ring opening” and cause the poor SEI formation. The results of MFPC with weaker electron withdrawing group give further support of this hypothesis. The bi-solvent electrolytes of Si-A/DMC and Si-B/DMC have comparable SEI formation capability as EC/DMC and TFPC/DMC, regardless of their bulky chains. This indicates that if proper chain structures are used, good SEI formation capability could be obtained for cyclic carbonate with bulky chains. These new solvents provide valuable information in studying the SEI formation mechanism and designing new electrolytes.     

双金属氰化络合物催化环氧丙烷和邻苯二甲酸酐共聚

采用双金属氰化络合物 (DMC)催化环氧丙烷 (PO)和邻苯二甲酸酐 (PA)共聚 ,探讨了共聚合特征 ,并用IR、1 H NMR和GPC对共聚物的结构和分子量进行了表征 .发现DMC催化剂对该共聚反应速度快 ,转化率高 ,是该反应的有效催化剂 ,催化剂浓度为 6 0mg kg时 ,90℃下 ,以THF作溶剂共聚反应 3h ,转化率可达94 0 % .聚合速度甚至比DMC催化PO均聚还快 .该共聚反应可在多种溶剂中进行 ,极性溶剂更有利于共聚合 ,溶液聚合温度比本体共聚低 ,合适的溶液共聚温度在 90～ 10 0℃之间 .共聚产物的分子量受催化剂用量、反应温度和体系中水份含量的影响 ,数均分子量在数百至数千之间 .考察该共聚体系的动力学表明 ,该共聚反应速率对单体浓度呈一级关系     

NaF含量对以水滑石结构为前驱体的固体碱催化剂F-Ca-Mg-Al及碳酸二甲酯合成的影响（英文）

以碳酸丙烯(PC)和甲醇为原料,经酯交换反应合成的多功能、环保的碳酸二甲酯(DMC)是一种绿色、节能的合成方法。CaO固体碱催化剂对该反应具有良好的催化性能,但其再生性不理想。以F-Ca-Mg-Al水滑石(LDHs)为原料,制备了一系列不同Na F用量的固体碱催化剂,并对其进行了表征和酯交换反应测试。与不加氟的FCMA-0催化剂相比,经氟改性后的催化剂的比表面积、碱量、催化活性等性能均有明显提高。催化活性由高到低依次为:FCMA-0.8> FCMA-0.4>FCMA-1.2> FCMA-1.6> FCMA-0,这与总碱位量和强碱位量一致。FCMA-0.8催化剂活性最好,与纯CaO催化剂的相当,PC转化率为66.8%,DMC选择性为97.4%,DMC收率为65.1%。在10次循环使用后,FCMA-0.8催化剂的DMC收率仅下降3.9%(CaO催化剂下降33.2%)。FCMA-0.8在PC与甲醇酯交换制DMC方面具有良好的工业应用前景。     

Acetone as oxidative decomposition product in propylene carbonate containing battery electrolyte

In situ differential electrochemical mass spectrometry (DEMS) and in situ subtractively normalized interfacial Fourier transform infrared spectroscopy (SNIFTIRS) were used to study the oxidative decomposition products of a propylene carbonate (PC) containing battery electrolyte at metal oxide electrodes. Hydrogen, carbon dioxide, ethane, ethene, propane and propene are typically evolved during electrolyte decomposition in lithium-ion batteries. In our SNIFTIRS and DEMS experiments, additional signals were detected which could not be attributed to these known products. Detailed analysis of these signals indicated the possible evolution of acetone as PC is oxidatively decomposed on the electrode surface.     

温和条件下电催化CO2与环氧丙烷合成碳酸丙烯酯

 在常温常压下研究了CO2的电化学活化及其与环氧丙烷反应合成碳酸丙烯酯,考察了支持电解质对碳酸丙烯酯产率的影响. 结果表明,含有Br-的支持电解质对合成碳酸丙烯酯起到明显的催化效果. 在实验研究基础上,对反应机理进行了初步推测,认为Mg2+起到路易斯酸的作用并与环氧丙烷的氧原子配位,同时Br-作为亲核试剂进攻环氧丙烷的 C-O 键使其断裂开环,形成的中间物与CO2还原产生的活化物质结合形成碳酸丙烯酯.