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1.
Seung Tae Hong Hyung Sang Park Jong Sung Lim Youn-Woo Lee Masakazu Anpo Jae-Duck Kim 《Research on Chemical Intermediates》2006,32(8):737-747
The synthesis of dimethyl carbonate (DMC) from methanol and supercritical carbon dioxide over various base catalysts has been
studied. Compounds of group-I elements (Li, Na and K) were used as base catalysts. The promoter and the dehydrating agent
were also used to enhance the yield of DMC. The effects of the catalysts, promoter and dehydrating agent on the yield of DMC
were investigated. By-products such as dimethyl ether (DME) and C1–C2 hydrocarbons were formed with the DMC as a main product. The yield of DMC with different alkali metal catalysts ranked in
the following order: K > Na > Li. The catalysts of the metal-CO3 compounds were more effective than the metal-OH compounds in DMC synthesis. The maximum DMC yield reached up to about 12
mol% in the presence of K2CO3 (catalyst), CH3I (promoter) and 2,2-dimethoxypropane (dehydrating agent) at 130–140°C and 200 bar. The reaction mechanism of DMC synthesis
from methanol and supercritical carbon dioxide was proposed. 相似文献
2.
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 总被引:4,自引:0,他引:4
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168%. 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. 相似文献
3.
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。 相似文献
4.
Summary A two-step synthesis of dimethyl carbonate (DMC) from ethylene oxide (EO), carbon dioxide and methanol using heterogeneous
anion exchange resins as catalysts is reported. The first step is the reaction of EO with CO2 to form ethylene carbonate (EC), and the second one the transesterification of EC with methanol to yield DMC. Effect of various
reaction parameters on the activity and selectivity of the catalysts used was investigated. After the first step, the crude
mixture containing EC was directly reacted with methanol in the presence of a heterogeneous anion exchange resin catalyst
to produce DMC in high yield and selectivity. Our process is highly economic. 相似文献
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Transesterification of dimethyl carbonate with phenol over a bimetallic molybdenum and copper catalyst 总被引:1,自引:0,他引:1
Dongshen Tong Tong Chen Fei Ma Tao Kang Yongcheng Lei Jing Hu Yue Wang Gongying Wang 《Reaction Kinetics and Catalysis Letters》2008,94(1):121-129
Mo-Cu bimetallic oxides were found to be efficient heterogeneous catalysts for the transesterification of dimethyl carbonate
(DMC) with phenol. When the reaction was carried out between 150 and 180°C, with a molar of Mo/Cu of 1:1, molar ratio of phenol/DMC
of 1:1, 4.8 wt.% of the catalyst, 9 h, the conversion of phenol was 49.9%, and the total yield of MPC and DPC was 45.4%. Catalyst
reuse showed a gradual decline in the catalytic activity. The decrease in catalytic activity might be due to leaching out
of Mo and Cu, and/or carbon deposition. 相似文献
7.
Structure and stability of solvation complexes of trimethyl phosphate and dimethyl methyl phosphonate 下载免费PDF全文
The presently used electrolytes in Lithium ion batteries, dimethyl carbonate (DMC), and ethylene carbonate are flammable. Trimethyl phosphate (TMP) and dimethyl methyl phosphonate (DMMP) have been shown to be potential nonflammable electrolytes. Density functional theory is used to calculate the structure and stability of the solvation complexes of TMP and DMMP. The calculations indicate that TMP and DMMP can form a solvation complex of the form Li+(X)4 where X is the TMP or DMMP molecule. Calculations of the solvation energy and bond dissociation energies to remove one TMP and DMMP from the solvation complexes are compared with the same calculations on DMC. The results indicate that TMP and DMMP are considerably more stable than DMC. 相似文献
8.
Fuming Mei Exiang Chen Guangxing Li Aiqing Zhang 《Reaction Kinetics and Catalysis Letters》2008,93(1):101-108
Mg-Al-O-t-Bu hydrotalcite was synthesized and characterized by XRD, FT-IR and TGA-DTA. It was proved to be an active heterogeneous
catalyst for the transesterification of dimethyl carbonate (DMC) with ethanol. When the reaction was carried out over Mg-Al-O-t-Bu
hydrotalcite at 80°C, 7 h, molar ratio of ethanol to DMC 5:1, 1.0 wt.% of catalyst, the conversion of DMC was 86.4%, the selectivity
to diethyl carbonate (DEC) was 61.2%. This heterogeneous catalyst could be used 5 times without loss of its activity. 相似文献
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Ca-Al催化剂上甘油与碳酸二甲酯酯交换合成碳酸甘油酯 总被引:2,自引:0,他引:2
生物柴油是一种环保、可再生、使用安全、可替代石化柴油的新型液体燃料,其产量和使用范围正逐年扩大。然而生物柴油生产过程中的主要副产物甘油严重过剩,因此甘油资源化转化和利用已经成为近年研究热点。甘油可以作为一种平台化合物实现向多种高附加值化学品的转化,例如通过催化氢解合成1,2-丙二醇,通过发酵和催化氧化制备二羟基丙酮,通过脱水制备丙烯醛和羟基丙酮,通过酯交换反应生成甘油酯等。其中,以甘油为原料合成的碳酸甘油酯(GC)具有很好的工业应用前景。以碳酸二甲酯(DMC)为原料与甘油进行酯交换合成GC是近年内比较有工业发展潜力的合成路线。前期研究发现,固体碱对该反应具有很好的催化活性,而且随着催化剂碱性增强,甘油转化率明显增加,然而当催化剂(如NaOH, KOH和K2CO3等)碱性过强时,产物选择性明显降低。水滑石类化合物是一种常见的碱性温和的固体催化剂,而且其碱性与结构可以调节,因此我们选择了一种常见水滑石——水铝钙石作为本研究的重点。 本文通过共沉淀法制备了一系列不同Ca/Al比(1–6)的Ca-Al水滑石,并以此作为前驱体制备了新型的固体碱催化剂。 XRD结果表明,当Ca/Al比为1–6时,所有样品都出现了明显的水滑石特征衍射峰,但当铝含量过高时会出现氢氧化铝杂相。 SEM结果发现,当Ca/Al =2–4时,样品中水滑石的结晶度高,有较完整的水滑石晶片, Ca/Al =6的样品中水滑石晶片较小, Ca/Al =1的样品中有明显的无定形氧化铝杂相。 TG-DSC结果表明, Ca/Al =2的样品除了几个与水滑石相关的特征失重峰以外,在786oC还检测到明显的热吸收峰,说明此时钙铝石已经发生分解,生成了单独的Ca12Al14O33晶相和氧化钙,这与SEM结果一致。这些水滑石经焙烧后用于温和条件下催化甘油与DMC酯交换生成GC的反应,发现上述催化剂对该反应具有很高的催化活性和目的产物选择性。当DMC与甘油的摩尔比为3时,70oC反应3 h后,甘油转化率达到93%, GC选择性高于97%。表征结果显示,甘油转化率主要取决于焙烧后Ca-Al催化剂中强碱性中心数量。其中经800oC焙烧后Ca/Al =2的样品中强碱性中心数量最多,因而表现出最高的催化活性。焙烧后催化剂中形成的Ca12Al14O33晶相在多次重复使用后仍可以稳定存在,但是表面CaO易流失,可能会降低催化剂的重复使用活性。 相似文献
13.
The synthesis of methyl acetoacetate (MAA) by methoxycarbonylation of acetone with dimethyl carbonate (DMC) was carried out
in the presence of MgO and alkali-promoted MgO catalysts. From among Li, Na, K, and Cs, potassium was found to be the most
effective promoter to improve the activity of MgO. The effect of K/MgO with variable content of K was also investigated, and
the individual catalysts were characterised by the XRD, BET, SEM, CO2-TPD, and in situ CO2 IR techniques. The results showed that the addition of a small amount of K (1.97 mass %) could promote MAA formation, but
a higher K loading caused a decrease in the yield of MAA, which might result from particle agglomeration and the presence
of stable potassium carbonates. In situ FTIR experiments of co-adsorbed reactants indicated that the reaction probably proceeded
via abstraction of Hα from acetone by base sites. 相似文献
14.
高稳定性CaO-ZrO2固体碱催化剂的表征和催化性能 总被引:3,自引:0,他引:3
用共沉淀法经高温焙烧制备了CaO摩尔分数从10%至50%的CaO-ZrO2系列催化剂, 将其应用于碳酸丙烯酯和甲醇酯交换合成碳酸二甲酯过程, 并通过XRD, FT-IR, BET, ICP, CO2-TPD, XPS等表征手段研究了催化剂的物性及其催化性能随组成变化的的规律. 结果表明, 当CaO摩尔分数高于30%时, 表面出现游离的CaO, 虽然具有强碱性和高活性, 但是稳定性差; 而当CaO摩尔分数低于30%时, Ca2+进入ZrO2晶格, CaO与ZrO2形成连续固溶体, 并且随着CaO含量的增加, 晶格氧的电荷密度增加, 催化剂的碱性增强, 使得CaO-ZrO2催化剂在碳酸丙烯酯和甲醇酯交换合成碳酸二甲酯过程中获得了高活性和高稳定性. 相似文献
15.
采用尿素热分解法制备锌铝水滑石,1 073 K下煅烧得到相应的锌铝复合氧化物催化剂。通过XRD谱图确定锌铝复合氧化物ZAO-3(1 073 K)催化剂的组分为ZnO相和ZnAl2O4尖晶石相。NH3(CO2)-TPD结果表明,当向ZnO中引入Al后,催化剂的酸碱性位和酸碱性强度都发生改变。采用原位红外(in-situ FT-IR)手段,研究了碳酸二甲酯(DMC)分别在ZAO-3(1 073 K)、ZnAl2O4、ZnO上随着温度变化的分解行为。结果表明,ZAO-3(1 073 K)催化剂上大量的弱酸碱性位协同稳定DMC,抑制DMC的分解。 相似文献
16.
金属醋酸盐催化合成聚丁二酸乙二醇酯预聚体和碳酸二甲酯 总被引:3,自引:0,他引:3
研究了醋酸盐催化碳酸乙烯酯(EC)和丁二酸二甲酯(DS)同时合成聚丁二酸乙二醇酯 (PES) 预聚体和碳酸二甲酯(DMC)的耦合反应新工艺。 采用气相色谱-质谱联用定性分析馏分组成;红外光谱、核磁共振表征了预聚物的结构;采用乌式粘度计测试了预聚物的特性粘数;气相色谱定量测定馏分碳酸二甲酯的收率以考察耦合反应的进度。 以对该反应催化效果最佳的无水醋酸锂为催化剂考察了物料配比、反应温度、反应时间、催化剂用量对耦合反应的影响,结果表明,最佳的工艺条件为:反应温度195~200 ℃,n(EC)∶n(DS)=2∶1,n(cat)∶n(EC+DS)=0.02∶1,反应时间为2 h,耦合反应所得的DMC收率为48.0%,聚丁二酸乙二醇酯预聚物的特性粘数为0.3787。 相似文献
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Lanthanum nitrate was an efficient and recoverable homogeneous catalyst for the transesterification of dimethyl carbonate
(DMC) with ethanol. It was reused 5 times for the transesterification without loss of its catalytic activity. 相似文献
18.
Ying-Jie Zhou Min Xiao Shuan-Jin Wang Dong-Mei Han Yi-Xin Lu Yue-Zhong Meng 《中国化学快报》2013,24(4):307-310
The Mo-promoted Cu-Fe bimetal catalysts were prepared and used for the formation of dimethyl carbonate(DMC) from CO2 and methanol.The catalysts were characterized by X-ray diffraction(XRD), temperature programmed reduction(TPR),laser Raman spectra(LRS),energy dispersive spectroscopy (EDS) and temperature programmed desorption(TPD) techniques.The experimental results demonstrated that the Mo promoters can decrease the reducibility and increase the dispersion of Cu-Fe clusters.The concentration balance of base-acid sites can be readily adjusted by changing the Mo content.The moderate concentration balance of acid and base sites was in favor of the DMC formation. Under optimal experimental conditions,the highest methanol conversion of 6.99%with a DMC selectivity of 87.7%can be obtained when 2.5 wt%of Mo was loaded. 相似文献
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采用共沉淀法制备了一系列 CuO/SiO2 催化剂,进行草酸二甲酯气相加氢活性评价,分别考察了不同沉淀剂(Na2CO3、NH3·H2O、NaOH)、催化剂组成以及反应工艺条件对加氢性能的影响。采用N2 吸附脱附、N2O吸附、XRD、TG热重分析、H2-TPR等手段对催化剂进行表征。结果表明,草酸二甲酯加氢反应活性与Cu0有关,提高铜比表面积有利于提高加氢活性。采用以NaOH沉淀剂制备的CuO质量分数为50%的CuO/SiO2催化剂,在200℃、2MPa、0.07h-1和氢酯摩尔比为100时,草酸二甲酯转化率可达 98%,乙二醇选择性87%,且催化剂表现出较好的稳定性。 相似文献
20.
KNO3/MCM-48催化酯交换法合成碳酸二丙酯 总被引:2,自引:0,他引:2
对KNO3/MCM-48用于丙醇和碳酸二甲酯进行酯交换合成碳酸二丙酯的催化性能进行了考察. 用X射线衍射(XRD)、红外光谱(IR)和X射线荧光法研究了催化剂的结构特征和表面性质. XRD结果表明,随着K负载量的增加,载体特征峰强度逐渐减弱,但仍保留MCM-48的晶体结构. 随着焙烧温度的升高, KNO3逐渐分解成K2O. 分别考察了活性组分负载量、焙烧温度、焙烧时间和催化剂的用量以及反应时间对反应的影响. 结果表明, KNO3/MCM-48催化剂对碳酸二丙酯的合成具有很高的催化活性. 在反应温度363 K, 反应时间6 h, 催化剂用量5%, 丙醇与碳酸二甲酯摩尔比为4的条件下,碳酸二甲酯的转化率可达99.9%, 产物碳酸二丙酯选择性93.4%, 产率93.3%. 相似文献