碳酸二甲酯与邻苯二酚合成愈创木酚的热力学分析

利用Benson基团贡献法计算了碳酸二甲酯,邻苯二酚,愈创木酚的热力学数据标准摩尔生成焓ΔfHm^θ、标准熵Sm^θ和热容Cp,m。对碳酸二甲酯与邻苯二酚催化合成愈创木酚反应体系进行了热力学分析,通过对反应的焓变ΔrHm,自由能变ΔrGm和平衡常数K的计算表明该反应是吸热反应,其自由能变化为负值,有较大的热力学平衡常数,且反应温度对平衡常数K影响不大,该反应可在较低温度下进行,在保持高转换率的同时,也可减少副反应,其关键是研制开发低温活性高的催化剂。     

尿素法合成碳酸二甲酯的研究进展

总结了从尿素出发合成碳酸二甲酯的三条工艺路线：尿素直接醇解路线、尿素-碳酸丙烯酯(或碳酸乙烯酯)-碳酸二甲酯路线、尿素-二苯基脲-苯氨基甲酸甲酯-碳酸二甲酯路线。对三条路线的反应过程、催化剂及优缺点进行了比较,认为尿素-碳酸丙烯酯(或碳酸乙烯酯)-碳酸二甲酯路线具有反应简单、产率和选择性高及反应步骤相对较少的优点。尿素醇解制备碳酸二甲酯的方法具有工业化前景。     

碳酸亚乙烯酯合成

以一氯碳酸乙烯酯和三乙胺为原料,碳酸二甲酯为溶剂合成碳酸亚乙烯酯。采用单变量考察对反应温度、反应溶剂、反应时间、物料摩尔比进行探索,得出最佳反应条件。反应温度55～65℃,反应时间15～16 h,原料投料比三乙胺∶一氯碳酸乙烯酯=1.20～1.30,溶剂投料比碳酸二甲酯∶一氯碳酸乙烯酯=2.2～2.4。产品收率65%,产品含量实测98.5%(气相色谱法)。     

乙二醇生产新技术研究进展

对乙二醇生产新技术进行了介绍，并对各公司新技术的工艺条件，反应转化率，选择性进行了对比，重点对乙二醇和碳酸二甲酯联产技术的优势进行了分析。充分利用环氧乙烷装置排放的二氧化碳来合成碳酸乙烯酯，然后进一步与甲醇反应乙二醇和碳酸二甲酯，该工艺路线不仅大大降低了生产成本，而且获得了高附加值环保型产品碳酸二甲酯，因而具有很好的发展前景。     

酯交换法合成碳酸二甲酯的催化剂研究

用ＺＳＭ－５分子筛作为甲醇和碳酸乙烯酯反应碳酸二甲酯 系的催化剂,通过对ＺＳＭ－５进行阳离子交换和浸渍法改性发现,ＺＳＭ－５分子筛碱性中心对反应起主要作用,适当强度的碱中心更有利于反应的正向进行。当甲 碳酸 乙酯的摩尔比为４：１,液时空速１ｍｌ／ｇｈ,反应温度１００℃,压力０．７ＭＰａ时,用碳酸钠改改性ＺＳＭ－５作催化剂,碳酸乙烯酯的转化率为５０％。     

酯交换法生产碳酸二甲酯优势明显

酯交换法是以碳酸丙烯酯或碳酸乙烯酯与甲醇酯交换反应生产碳酸二甲酯,同时联产丙二醇或乙二醇。酯交换法生产碳酸二甲酯实质上是将碳酸二甲酯和二元醇的生产耦合在一起。近年来华东理工大学对CO2与环氧丙烷合成碳酸丙烯酯的技术进行了重大改进,使能耗大幅下降;对酯交换反应精馏塔做了重大改进,使反应的转化率和选择性都超过99％;     

耦合反应在碳酸二甲酯合成反应中的应用

本文运用化学热力学基本原理,着重从热力学角度对碳酸二甲酯的合成反应进行了探讨,表明使用耦合反应是提高碳酸二甲酯产率的重要方向。     

不同反应原料合成碳酸二苯酯的热力学研究

采用密度泛函理论(DFT),对碳酸二苯酯(DPC)的不同合成反应路径进行了热力学分析。首先优化了反应中涉及的各种物质在气体状态下的稳定结构,在此基础上计算了各物质液体状态下的热力学性质,获得了碳酸二甲酯-苯酚(DMC-Ph OH),碳酸二甲酯-乙酸苯酯(DMC-PA)两种不同酯交换反应路径的焓变、熵变、吉布斯自由能变以及平衡常数。计算结果表明,两种合成反应均为吸热反应;从热力学角度来看,DMC-PA反应路径优于DMC-Ph OH反应路径,其反应平衡常数更大,利于DPC的生成。但两种合成路径各步反应的平衡常数KC均偏小,为提高DPC收率,需要在反应进行过程中,不断移走产物以打破热力学平衡限制。同时,从热力学角度分析,若DMC同Ph OH的反应采用"两步法",DMC同PA的反应采用"一步法",则较有利于DPC的生成。     

酯交换法合成碳酸二甲酯的反应动力学

主要研究1,8-二氮杂二环十一碳-7-烯(DBU)催化碳酸乙烯酯和甲醇酯交换反应合成碳酸二甲酯的反应动力学.首先假设碳酸二甲酯的反应机理,在此基础上建立动力学模型,得到相应的动力学方程.通过实验数据处理,线性回归计算得到动力学方程的未知参数,最终得到反应速率r=4.2889e-15763/RT cEC cMEOH-49...     

碳酸乙烯酯酯交换合成碳酸二苯酯

为利用碳酸乙烯酯固定的CO2,拓展碳酸二苯酯的合成方法,对碳酸乙烯酯酯交换合成碳酸二苯酯的反应进行了热力学分析,并考察了催化剂、反应温度、催化剂质量分数和反应时间对合成碳酸二苯酯的影响。结果表明:碳酸乙烯酯与苯酚的酯交换反应在热力学上是不可行的,而将苯酚乙酰化后可以实现由碳酸乙烯酯经酯交换合成碳酸二苯酯;不同催化剂催化酯交换反应时,n-Bu2SnO显示了最高的酯交换选择性。当反应温度为190℃,碳酸乙烯酯与乙酸苯酯的摩尔比为1∶2,n-Bu2SnO质量分数8%,反应时间10 h时,碳酸乙烯酯的转化率为15.1%,酯交换选择性64.2%,碳酸二苯酯的收率7.5%。     

乙酰乙酸乙酯金属配合物催化丁二酸二甲酯和碳酸乙烯酯的耦合反应

研究了乙酰乙酸乙酯金属配合物催化碳酸乙烯酯(EC)和丁二酸二甲酯(DMSu)同时合成聚丁二酸乙二醇酯(PES)预聚体和碳酸二甲酯(DMC)耦合反应新工艺。结果表明,以乙酰乙酸乙酯锌为催化剂,反应温度205～215℃,n(乙酰乙酸乙酯锌)/n(EC+DMSu)=0.001,n(EC)/n(DMSu)=4,反应时间1 h时,DMC收率为52.3%,PES的特性黏度为0.117 4 dL/g。     

Simultaneous synthesis of dimethyl carbonate and ethylene glycol dimethacrylate using homogenous basic catalyst

A novel method simultaneously to prepare dimethyl carbonate and ethylene glycol dimethacrylate from ethylene carbonate and methyl methacrylate has been demonstrated in the presence of catalyst sodium methoxide and polymerization inhibitor ZJ-705. The effect of reaction parameters such as catalyst loading, polymerization inhibitor loading, concentration of reactants, reaction time, etc., on synthesis of dimethyl carbonate and ethylene glycol dimethacrylate was investigated. A reaction mechanism has been discussed with catalyst sodium methoxide.     

Optimization of supercritical dimethyl carbonate (SCDMC) technology for the production of biodiesel and value-added glycerol carbonate

In the present study, biodiesel has been successfully produced from triglycerides and dimethyl carbonate, instead of the conventional alcohol. In this non-catalytic supercritical dimethyl carbonate (SCDMC) technology, valuable compound of glycerol carbonate is obtained as side product, rather than the undesirable glycerol. Glycerol carbonate has higher commercial value compared to glycerol and its application in industries is enormous. In this optimization study, the effects of important parameters including reaction temperature, molar ratio of dimethyl carbonate to oil and reaction time were investigated and optimized by employing response surface methodology (RSM) analysis. It was found that the mathematical model developed was statistically significant and adequate to predict the optimum yield. The optimum conditions for SCDMC process was found to be 380 °C for reaction temperature, 39:1 mol/mol of dimethyl carbonate to oil molar ratio and 30 min of reaction time to obtain 91% optimum yield of biodiesel.     

有机锡催化碳酸乙烯酯与丁二酸二甲酯耦合反应

以含有不同取代基的有机锡化合物为催化剂,通过碳酸乙烯酯（EC）与丁二酸二甲酯（DMSu）耦合法制备了聚丁二酸乙二醇酯（PES）和碳酸二甲酯（DMC）,并对PES的结构进行了表征。结果表明,有机锡取代基团的电子效应和空间位阻对其催化性能具有很大影响;取代基的吸电子效应越大、空间位阻越小,有机锡的催化活性越高,但若有机锡中存在B酸中心时则容易引起副反应,导致产物选择性差。综合考虑,Bu₂SnO的催化性能最好,最优反应条件下,DMC的收率可达到70.08%,PES的特性黏数可达到0.622 dl·g^-1。     

Simultaneous Synthesis of Dimethyl Carbonate and Poly（ethylene terephthalate） Using Alkali Metals as Catalysts

Dimethyl carbonate （DMC） and poly（ethylene terephthalate） was simultaneously synthesized by the transesterification of ethylene carbonate （EC） with dimethyl terephthalate （DMT） in this paper. This reaction is an excellent green chemical process without poisonous substance. Various alkali metals were used as the catalysts. The results showed alkali metals had catalytic activity in a certain extent. The effect of reaction condition was also studied. When the reaction was carded out under the following conditions： the reaction temperature 250℃, molar ratio of EC to DMT 3 ： 1, reaction time 3h, and catalyst amount 0.004 （molar ratio to DMT）, the yield of DMC was 68.9%.     

氧化锌催化丁二酸二甲酯和碳酸乙烯酯的耦合反应

研究了ZnO催化碳酸乙烯酯和丁二酸二甲酯耦合反应合成聚丁二酸乙二醇酯预聚体和碳酸二甲酯的新工艺。考察了ZnO催化剂焙烧温度对耦合反应的催化活性,优化了反应条件。并对ZnO催化剂进行XRD、BET和NH₃-TPD表征。以FTIR和¹H NMR表征聚丁二酸乙二醇酯预聚体。结果表明,在225~235℃,EC/DMSu摩尔比为2,催化剂/(EC+DMSu)摩尔比为0.005,反应时间为3 h的反应条件下,碳酸二甲酯收率为59.7%,聚丁二酸乙二醇酯预聚物的特性黏度为0.3857 dl·g^-1。通过XRD和NH₃-TPD分析,推测ZnO表面的晶体缺陷和弱酸性是影响耦合反应催化活性的原因。     

Electrochemical behavior of copper current collector in imidazolium-based ionic liquid electrolytes

The electrochemical behaviors of copper current collector in 1-alkyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl] imide ionic liquid electrolytes were investigated and compared with that in ethylene carbonate/dimethyl carbonate solutions. Cyclic voltammetry results showed that large oxidation–reduction current of the copper foil appeared in ethylene carbonate/dimethyl carbonate solutions, while a much smaller current in the room temperature ionic liquid electrolytes decreased gradually, indicating that the copper foil was anodically stable. Further study by X-ray photoelectron spectroscopy analysis showed that an unstable product was composed mainly of the carbonate and carbonyl species on the surface of the copper foil after the electrochemical measurement in ethylene carbonate/dimethyl carbonate solutions, leading to the dissolution of the copper foil. While a better passivating film from the reduction of the anions in the room temperature ionic liquid electrolytes covered the surface of copper foil and protected the copper foil from being oxidized even in a higher potential. These results indicate that the use of room temperature ionic liquid electrolytes can improve the stability of copper current collector in the advanced lithium ion batteries.     

镁铝复合氧化物负载NaAlO2催化剂制备及其催化性能研究

以恒定pH共沉淀法制备的镁铝水滑石为前驱体,NaAlO₂为活性组分,在一定温度下焙烧得到镁铝复合金属氧化物负载铝酸钠催化剂。利用XRD、SEM、BET、CO₂-TPD、DSC-TG等手段对催化剂进行表征,发现通过高温焙烧可实现铝酸钠在镁铝复合金属氧化物表面的稳定分散。该催化剂可在温和反应条件下催化碳酸乙烯酯和甲醇酯交换反应合成碳酸二甲酯（DMC）和乙二醇（EG）,表现出高催化活性及对产物的高选择性。在醇酯物质的量比为10∶1、4 h、65 ℃条件下,DMC收率为74.8%,对DMC和EG的选择性均为100%。循环实验过程中,催化剂表现出较好的稳定性,使用5次后催化活性未见明显下降。该催化剂制备方法简单、成本低,催化剂易与产物分离,可多次重复使用,是一种低温高活性酯交换固体碱催化剂,具有一定的工业应用前景。     

Kinetics measurement of ethylene-carbonate synthesis via a fast transesterification by microreactors

High-purity ethylene carbonate (EC) is widely used as battery electrolyte, polycarbonate monomer, organic intermediate, and so on. An economical and sustainable route to synthesize high-purity ethylene carbonate (EC) via the transesterification of dimethyl carbonate (DMC) with ethylene glycol (EG) is provided in this work. However, this reaction is so fast that the reaction kinetics, which is essential for the industrial design, is hard to get by the traditional measuring method. In this work, an easy-to-assemble microreactor was used to precisely determine the reaction kinetics for the fast transesterification of DMC with EG using sodium methoxide as catalyst. The effects of flow rate, microreactor diameter, catalyst concentration, reaction temperature, and reactant molar ratio were investigated. An activity-based pseudo-homogeneous kinetic model, which considered the non-ideal properties of reaction system, was established to describe the transesterification of DMC with EG. Detailed kinetics data were collected in the first 5 min. Using these data, the parameters of the kinetic model were correlated with the maximum average error of 11.19%. Using this kinetic model, the kinetic data at different catalyst concentrations and reactant molar ratios were predicted with the maximum average error of 13.68%, suggesting its satisfactory prediction performance.