负载型金属氧化物催化酯交换合成碳酸二甲酯

制备了多种以γ - Al2O3为载体的负载金属氧化物催化剂,考察其在由碳酸乙烯酯(EC)与甲醇(ME)酯交换法合成碳酸二甲酯(DMC)中的催化活性,其中以K2 O/γ - Al2 O3催化活性较好.同时考察了负载量、催化剂用量、甲醇与碳酸乙烯酯摩尔比、反应温度、反应时间等因素对反应的影响,最终确定最佳反应条件:催化剂为K2O/γ - Al2O3,甲醇与碳酸乙烯酯摩尔比为5,m(催化剂)∶m(甲醇)为1∶200,反应温度为65℃,反应时间为3h,在此条件下,碳酸二甲酯收率最佳为52.0％.     

有机锡均相催化反应蒸馏合成碳酸二苯酯

通过对碳酸二甲酯(DMC)与苯酚酯交换法反应蒸馏合成碳酸二苯酯(DPC)的研究,筛选合适的催化剂和寻找最佳的工艺条件,为DPC的工业化打下基础。实验结果表明,在常压下,温度145℃,原料配比n(PhOH)∶n(DMC)=3∶1,n(PhOH)∶n(催化剂)=1∶0.012,反应时间10h,碳酸二甲酯总转化率为32.04%,DPC产率为18.00%,碳酸苯甲酯(MPC)产率为14.04%,DPC的选择性为56.18%,而且无苯甲醚和CO2生成,所选催化剂二丁基二月桂酸锡的催化性能明显优于路易斯酸。     

双酚A型聚碳酸酯的合成与性能研究进展

对双酚A型聚碳酸酯的合成与性能进行了系统综述.详细介绍了光气法、氧化羰化法和酯交换法催化合成聚酯方面的研究进展,分析了催化剂和反应工艺条件对聚醋合成的影响,指出各种合成方法存在的优缺点.酯交换法是非光气合成聚酯的重要方法,其中包括碳酸二苯酯(DMC)法和碳酸二甲酯(DMC)法.在DPC合成法中,副产物苯酚的脱挥比较困难,往往需要在高温低压条件下进行,因此在缩聚过程中常常伴随副反应发生,造成产品质量下降.DMC是合成DPC的重要原料,开发DMC直接合成聚碳酸酯,避免了中间体DPC的合成,减少了反应步骤.与DPC法相比较,DMC法中副产物甲醇脱挥比较容易,但该反应平衡转化率低,因此需要选择合适的工艺条件促进平衡移动.此外,在聚酯性能和改性方面也进行了系统分析,展望了合成和改性的研究前景.     

几种新型3LCuCl配合物的合成及其对甲醇氧化羰基化反应催化性能研究

甲醇液相氧化羰基化合成碳酸二甲酯是一碳化学研究的重要应用领域之一,其核心工作是反应催化剂的开发和使用.本项工作从仿生催化的角度进行催化剂结构设计,合成三种结构新颖的氯化亚铜的配合物,分别具有N-N-N、N-O-N和N-S-N新型配体,并用于甲醇液相氧化羰基化催化反应,在工业生产的反应条件(120℃/2.4 MPa)下研究了它们在合成碳酸二甲酯反应中的催化性能. 5 h后的实验结果显示,N-O-N型配合物对碳酸二甲酯的时空转化率高于81 g·DMC/(g·cat·h),但选择性低于90%. N-N-N型配合物对碳酸二甲酯的催化选择性在94%以上,但时空转化率只有37.5 g·DMC/(g·cat·h). N-S-N型配合物综合催化效果不佳.实验结果说明杂原子和金属离子的配位能力过强对催化性能不利,如何在选择性与时空转化率之间取得较好的平衡需要进一步探讨.     

酯交换法合成碳酸二苯酯

碳酸二苯酯(DPC)是一种重要的精细化工中间体,主要用于合成许多有机化合物和高分子材料。目前,合成碳酸二苯酯方法有光气法、氧化羰基化法和酯交换法。酯交换法合成DPC主要是通过苯酚与碳酸二甲酯(DMC)反应合成,在100～200℃常压或加压的条件下进行,反应设备简单、毒性和腐蚀性小,产率较高,是一种绿色合成方法。     

非光气法合成碳酸二甲酯研究的新进展

对酯交换法、甲醇氧化羰基化法、二氧化碳甲醇直接合成法等非光气路径合成碳酸二甲酯 (DMC)工艺的最新研究状况进行了综述 ,分析比较了各种合成工艺的优缺点 ,探讨了我国今后在DMC合成工艺研究方面的发展方向 .     

碳酸二甲酯生产技术发展趋势

碳酸二甲酯(Dimethyl carbonate以下简称DMC)作为21世纪的重要化工产品,目前正受到世界各国越来越多的重视。众所周知,硫酸二甲酯(DMS)、光气(COCl_2)两种有机化工产品系重要的甲基化和羰基化试剂,在农药、医药、聚氨酯、有机化工等行业有广泛的用途。但这两种产品均系剧毒品,随着人类环保意识的加强,急需开发一种新的低毒或无毒代用品,碳酸二甲酯应运而生。碳酸二甲酯于1992年在欧洲通过非毒性化学品的注册登记,作为一种无毒的化学品,同时又因特殊的化学结构而具有优良的反应活性,DMC正在许多领域有望全面替代剧毒的光气、硫酸二甲酯等,从而成为未来世界化学合成的新基块。 DMC生产方法可分为三大类:即光气法、酯交换法和羰基合成法。光气法又可分为光气甲醇法和光气醇钠法。羰基合成法又可分为液相氧化羰基化法和气相氧化羰基化法。 1.光气甲醇法 该法是古老而经典的合成法,首先由光气与甲醇合成氯甲酸甲酯,氯甲酸甲酯进而与甲醇反应得DMC。此法可工业规模生产DMC,但存在工艺复杂,操作周期长,原料(光气)剧毒,副产HCl腐蚀严重,污染环境,安全性差等问题,不宜推广。     

负载型固体碱催化制备生物柴油的研究

以负载型固体碱(KF/Al2O3、KNO3/Al2O3和K2CO3/Al2O3)作催化剂,菜籽油与甲醇通过酯交换反应制备生物柴油,系统地研究了催化剂制备条件及酯交换条件对产物收率的影响.结果表明:以上3种催化剂都可以较好地催化酯交换反应,其中负载KF催化剂的催化效果更好一些.当催化剂焙烧温度为873 K、负载物和载体的质量比为0.15~0.20时制备的催化剂活性最强,用此催化剂催化酯交换反应,当醇油摩尔比为12∶1~10∶1、催化剂用量为2%~3%、时间为60 min、温度为333~338 K时,生物柴油收率可达85%~87%.     

镧化合物催化酯交换合成碳酸二乙酯

以碳酸二甲酯(DMC)与乙醇进行酯交换法合成碳酸二乙酯(DEC),并考察不同催化剂、催化剂用量、反应时间、反应配比、催化剂重复性使用对反应的影响。结果表明,无水硝酸镧催化碳酸二甲酯与乙醇的酯交换反应具有优良的活性;当反应温度为76~80℃,乙醇与DMC摩尔比为8∶1,催化剂用量占DMC量的0.7%(摩尔分数)时,反应7h后DMC的转化率为86.0%,碳酸二乙酯和碳酸甲乙酯(EMC)的产率分别为59%和26.5%,酯交换反应的选择性为99.4%;催化剂无水硝酸镧在重复使用5次后仍具有很好的催化活性。     

Ni/Al水滑石催化DMC与苯酚的酯交换反应研究

通过水热合成法制备了Ni/Al水滑石催化剂,并测试了其催化DMC与苯酚酯交换反应的性能,考察了沉淀剂和镍铝摩尔比对Ni/Al水滑石活性的影响。结果发现,Ni/Al水滑石具有较好的酯交换催化活性,且以尿素为沉淀剂制备的Ni/Al水滑石晶型较好,目标产物的选择性也较高。进一步研究表明,均一的水滑石物相对酯交换反应的催化活性有利,在镍铝摩尔比为1:1,n(Urea):n(NO3-)=1:1,100℃水热合成条件下制备的催化剂的催化活性最好,碳酸二甲酯(DMC)的转化率为20.2%,甲基苯基碳酸酯(MPC)和碳酸二苯酯(DPC)的收率分别为13.1%和3.8%。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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