Synthesis of diphenyl carbonate from dimethyl carbonate and phenol using O2-promoted PbO/MgO catalysts

Various heterogeneously supported PbO catalysts were prepared for the synthesis of diphenyl carbonate (DPC) by transesterification of dimethyl carbonate (DMC) with phenol. MgO was found to be the best support, and the modification by oxygen further enhanced the catalytic activities of PbO/MgO catalysts. Several parameters affecting the transesterification were investigated. The yields of methylphenyl carbonate (MPC) and DPC reached 10% and 26.6%, respectively, over 10 wt% O₂-promoted PbO/MgO catalyst which was prepared by impregnation method. X-ray diffraction (XRD), differential thermal analysis (DTA) and Brunauer–Emmet–Teller (BET) technique were employed for the characterization of prepared catalysts. It was discovered that the structure and the oxidation states of lead species in PbO/MgO catalysts changed after the promotion by oxygen.     

V-Cu氧化物催化碳酸二甲酯与苯酚酯交换反应

研究了一系列钒-金属复合氧化物对碳酸二甲酯(DMC)和苯酚酯交换合成碳酸二苯酯(DPC)的催化性能,实验结果表明,钒-铜复合氧化物是较好的酯交换合成DPC的催化剂。考察了V/Cu摩尔比,催化剂用量,DMC用量和反应时间对酯交换反应的影响,得到较佳的反应条件： n(V):n(Cu) = 4:1,苯酚用量0.16 mol,V-Cu复合氧化物催化剂的用量为苯酚用量的3.1%（质量比）, n(DMC) : n(苯酚) = 1.5 :1,反应时间9～15 h。在此条件下反应9 h,苯酚的转化率为41.9%,甲基苯基碳酸酯(MPC)及DPC的总收率为40.3%。催化剂重复使用4次后苯酚转化率从41.9%降到29.1%,多次重复使用后的催化剂在空气氛中焙烧即可再生,再生催化剂的催化性能几乎和新鲜催化剂相当,苯酚转化率达到39.8%。     

The transesterification of dimethyl carbonate and phenol catalyzed by 12-molybdophosphoric salts

Various 12-molybdophosphoric salts were used in the transesterification of dimethyl carbonate (DMC) and phenol to diphenyl carbonate (DPC) and methyl phenyl carbonate (MPC) as novel solid catalysts. The zinc salt was found to exhibit the highest activity for the transesterification. Several parameters affecting the transesterification were investigated. When the reaction was performed between 150 °C and 180 °C, with a molar ratio of phenol to DMC of 1, a reaction time 12 h, a catalyst amount 0.004 (molar ratio to phenol), the conversion of phenol reached 31%, and the selectivity of MPC and DPC was 29% and 66.1%, respectively. The TON reached 74.8 mol (MPC + DPC)/mol Zn-salt.     

Transesterification of Dimethylcarbonate and Phenol Over Silica Supported TiO2 and Ti-MCM 41 Catalysts: Structure Insensitivity

Silica-supported titanium dioxide (TiO₂/SiO₂) and Ti-MCM 41 catalysts have been used for transesterification of dimethylcarbonate (DMC) and phenol to methylphenylcarbonate (MPC). The structure and the chemical state of titanium species in TiO₂/SiO₂ and Ti-MCM 41 have been investigated by means of X-ray diffraction (XRD), X-ray absorption near edge structure (XANES) for Ti K-edge and X-ray photoelectron spectroscopy (XPS). To understand the role of pore size on the activity of catalysts, different pore size silica supports (Q-series) were utilized in TiO₂/SiO₂ catalysts. Similarly, to understand the effect of Ti symmetry on the activity of catalysts, Ti-MCM 41 was used with different Ti-loadings. It was observed that the Ti surface area was an only important factor to achieve highest activity. In case of Ti-MCM 41 catalysts, as the Ti-loading increased octahedral symmetry increased and tetrahedral symmetry decreased. But, turnover rates based on the surface Ti atoms were independent of the Ti symmetry. They are also similar to those obtained for TiO₂/SiO₂ catalysts. Showing that transesterification of DMC and phenol over Ti-based catalysts is a structure insensitive reaction.     

Oxidative carbonylation of methanol to dimethyl carbonate over CuCl/SiO2–TiO2 catalysts prepared by microwave heating: The effect of support composition

Copper(I) chloride catalysts with a loading of 20 wt%, supported on silica–titania mixed oxides with Si/Ti ratios of 1, 5, 10 and 50 were prepared by conventional and microwave heating methods and tested in the oxidative carbonylation of methanol to dimethyl carbonate (DMC). X-ray diffraction (XRD), nitrogen adsorption, X-ray photoelectron spectroscopy (XPS) and thermal gravimetric analysis (TGA) were used to examine the bulk and surface properties of the CuCl/SiO₂–TiO₂ catalysts. Quantum-chemical calculations were performed to explore the interaction of CuCl with the silica–titania support. Microwave heating showed some significant advantages over the conventional heating method, with markedly reduced preparation temperature and time, and provided improved catalytic activity in the oxidative carbonylation of methanol. The catalytic behavior of CuCl/SiO₂–TiO₂ in the test reaction studied was strongly dependent on the support composition. Incorporation of tetrahedral Ti(IV) species into the silica matrix could enhance the interaction of copper species with the oxide support. The improved catalytic performance of CuCl/SiO₂–TiO₂ in the DMC synthesis can be understood by the existence of the strong coordination interactions between the Cu⁺ centers of CuCl and the bridging oxygen atoms at the Si–O–Ti bonds in the silica–titania support.     

碳酸二甲酯与苯酚酯交换合成碳酸二苯酯研究

选择Lewis酸催化剂、分子筛催化剂、有机钛和锡化合物催化剂和不同负载型金属氧化物催化剂用于碳酸二甲酯(DMC)与苯酚酯交换合成碳酸二苯酯(DPC)的过程。试验结果表明,：MoO3/SiO2和TiO2／SiO2催化剂对该反应具有相对较好的催化活性和选择性。以MoO3／SiO2为催化剂,DMC转化率和DPC选择性分别为24.3％和37.6％;以TiO2／SiO2,为催化剂,DMC转化率和DPC选择性分别为13.7％和20.0％。在该酯交换反应中,SiO2与Al2O3和MgO相比,是一种良好的催化剂载体。     

Lewis酸催化酯交换合成碳酸二苯酯研究

研究了几种Lewis酸催化酯交换合成碳酸二苯酯 (DPC) ,其中AlCl3 具有最高的催化活性。在常压下 ,1 6 0～ 1 90℃时 ,当n (苯酚 )∶n (碳酸二甲酯 )∶n (AlCl3 ) =4∶1∶0 0 6 ,反应时间 1 4h ,碳酸二甲酯 (DMC)转化率为 2 5 5 % ,DPC产率 2 2 3% ,碳酸甲苯酯 (MPC)产率 2 2 % ,苯甲醚1 0 % ,DPC的选择性 87 5 %。     

类水滑石催化剂催化合成碳酸二丙酯

采用共沉淀法,在500 ℃烘干焙烧制备了类水滑石催化剂,采用X射线衍射（XRD）、红外光谱（FT-IR）、BET分析对催化剂进行了表征。将类水滑石催化剂应用于碳酸二甲酯（DMC）与正丙醇酯交换合成碳酸二丙酯（DPC）。研究结果表明：镁铝摩尔比为2∶1,在500 ℃焙烧后,类水滑石对反应有较高的催化活性;当丙醇∶DMC =3∶1（摩尔比）、催化剂用量为反应物总质量的1%、反应温度为90 ℃、反应时间为5 h时,DPC的收率为46.87%。     

Single-step catalytic synthesis of diphenyl carbonate over transition-metal-substituted Keggin-type tungstophosphoric acid

Single-step catalytic synthesis of diphenyl carbonate (DPC) through the transesterification of dimethyl carbonate (DMC) and phenol could be firstly arrived by using the transition-metal-substituted polyoxometalates (TMS-POMs) K₅[PW₁₁O₃₉M(H₂O)]/TiO₂ system (M = Mn^II, Co^II, Ni^II, Cu^II, Zn^II). The catalytic activity of this transesterification was strongly influenced by the type of transition metal in the TMS-POMs. Among them, the K₅[PW₁₁O₃₉Zn(H₂O)]/TiO₂ catalytic system showed the highest activity and selectivity for DPC. The conversion of phenol reached 12.8%, and the selectivity to DPC was 83.6%. The turnover number (TON) reached 6.44 × 10⁴ mol/mol [PW₁₁O₃₉Zn(H₂O)]⁵⁻/TiO₂. A possible mechanism that the transition metal in the polyoxometalates anchored DMC to form intermediate compound in the transesterification was proposed.     

酯交换合成碳酸二苯酯反应及催化剂研究进展

介绍了碳酸二甲酯与苯酚酯交换合成碳酸二苯酯的反应热力学。总结了近年来该类催化剂研究的新进展。对酯交换反应的平衡限制问题和选择性问题进行了详细的讨论。根据对反应热力学的分析,指出避开平衡限制的合理途径是采用酯交换-歧化二步法工艺路线,而高选择性地得到碳酸二苯酯取决于催化剂的性质。通过分析酸碱催化作用在酯交换反应中的差异,认为碱催化是副产物苯甲醚生成的主要原因,Lewis酸性的催化剂有利于碳酸二苯酯的高选择性。最后对国内研究现状进行了评价和展望。     

酯交换合成碳酸二苯酯催化剂的研究进展

对近年来碳酸二甲酯和苯酚酯交换合成碳酸二苯酯的催化剂体系进行了较为系统的概述,包括均相催化剂体系(碱或碱金属化合物、Lewis酸、锡和钛的有机化合物等)和多相催化剂体系(各种负载型、金属氧化物、水滑石等),认为开发有机锡、有机钛配合物催化剂以及将其固载化是碳酸二甲酯与苯酚酯交换反应合成碳酸二苯酯催化剂研究的重要方向.     

钛酸钾催化DMC酯交换反应合成碳酸二异辛酯的研究

研究了碳酸二甲酯（DMC）与异辛醇（EHOH）酯交换合成碳酸二异辛酯（DEHC）的反应,对几种钾盐的催化性能比较,发现K2TiO3具有较好的催化活性和选择性。实验结果表明,K2TiO3为催化剂时,最佳反应条件为：反应温度140 ℃,反应时间2 h,n(DMC)∶n(EHOH)=1∶3,催化剂用量为原料总质量的1%,DMC转化率为72.1%,DEHC收率为57.6%,DEHC选择性为79.2%。     

Efficient synthesis of 1,6-hexamethylene diurethane through coupling transesterification and methoxycarbonylation with methyl phenyl carbonate as intermediate

A reaction coupling system of transesterification and methoxycarbonylation with methyl phenyl carbonate (MPC) as intermediate was established to efficiently prepare 1,6-hexamethylene diurethane (HDU) from 1,6-hexamethylene diamine (HDA). The feasibility of the system was explored using the thermodynamics analysis, the reaction mechanism and the experiment results. The optimal reaction was carried out to get higher HDU yield. The thermodynamic analysis showed that the methoxycarbonylation of HDA with MPC, the Gibbs free energy of which was negative, was a spontaneous process. Furthermore, the equilibrium constant of the methoxycarbonylation of HDA with MPC was much greater than that of the transesterification of dimethyl carbonate (DMC) with phenol, so the reaction coupling could be realized under mild conditions. The reaction mechanism analysis indicated that phenoxy anion was the key species for reaction coupling. Higher MPC concen-tration was detected when sodium phenoxide was used as transesterification reactant with DMC, since the phenoxy anion of sodium phenoxide could be dissociated more easily. Sodium phenoxide was more suitable to prepare HDU through reaction coupling. A yield of HDU as high as 98.3%could be reached under the optimal con-ditions of mPhONa/mDMC=0.027 and nDMC/nHDA=8/1 at 90 °C in 2 h.     

碳酸二苯酯的合成工艺进展

讨论了光气法、酯交换法及氧化羰化法合成碳酸二苯酯的工艺路线及相关催化剂。重点讨论酯交换法催化剂的选择及反应装置的设计开发,对氧化羰化法则侧重于催化剂的研究开发。     

碳酸甲苯酯的合成及光谱研究

通过苯酚和碳酸二甲酯的酯交换反应合成了碳酸甲苯酯,采用减压精馏对其进行了分离提纯,得到纯度>99.5%的碳酸甲苯酯;运用红外光谱、紫外光谱、核磁共振氢谱以及质谱对其结构进行了表征,并对其光谱数据进行了解析。     

Clean synthesis of methyl N‐phenyl carbamate over ZnO‐TiO2 catalyst

BACKGROUND: Methyl N‐phenyl carbamate (MPC) is an intermediate for the preparation of methylene diphenyl diisocyanate (MDI), which is an important monomer for polyurethane synthesis. The synthesis of MPC by the reaction of aniline and dimethyl carbonate (DMC) is becoming more and more attractive. However, most of the catalysts used in MPC synthesis are homogeneous and not environment‐friendly. Therefore, it is important and necessary to develop a new kind of oxide catalyst, that is not only friendly to the environment, but also exhibits higher activity and longer service time. RESULTS: A new heterogeneous catalyst, ZnO‐TiO₂, was prepared for MPC synthesis. ZnO‐TiO₂ catalyst with a molar ratio Ti/Zn = 2 and calcined at 673 K exhibited good catalytic activity: aniline conversion was 96.9% and MPC yield 66.7%. CONCLUSION: ZnO‐TiO₂ exhibits better catalytic activity than ZnO or TiO₂ alone, which may result from the formation of ZnTiO₃ and Zn₂TiO₄. Compared with ZnTiO₃, Zn₂TiO₄ has better selectivity for MPC synthesis. Lewis acid sites with weaker acid strength favour MPC synthesis. The catalyst activity can be recovered almost completely by calcination. Copyright © 2008 Society of Chemical Industry     

酯交换法合成碳酸二苯酯的反应工艺

简要介绍了酯交换法合成碳酸二苯酯的反应原理。对碳酸二苯酯合成及碳酸二甲酯/苯酚分离法、分区反应法、连续法、反应精馏法和偶联法5种酯交换法合成碳酸二苯酯的反应工艺进行了详细讨论。其中反应精馏法及偶联法是创新的工艺,其反应工艺简单,原料利用率高,碳酸二苯酯的产率和选择性均很高。     

离子液体催化碳酸二甲酯和乙醇酯交换合成碳酸甲乙酯

考察了碱性离子液体催化碳酸二甲酯和乙醇酯交换反应合成碳酸甲乙酯的过程, 筛选出催化性能较好的离子液体1-丁基-3-甲基咪唑溴盐（［Bmim］Br）作为催化剂, 并对酯交换反应条件进行优化。结果表明,［Bmim］Br对反应表现出优异的催化性能,在常压、反应温度90 ℃、反应时间12 h、n(碳酸二甲酯)∶n(乙醇)=1∶1和［Bmim］Br用量为碳酸二甲酯质量的2%条件下,碳酸二甲酯转化率为71.1%,碳酸甲乙酯选择性为81.8%。经回收和循环利用 3次,催化剂仍保持较好的催化活性。     

碳酸二丙酯的绿色合成及其与DMC相平衡数据测定

用碳酸二甲酯(DMC)与正丙醇(n-PrOH)酯交换反应合成了碳酸二丙酯(DPC),考察了催化剂种类、物料摩尔比、催化剂用量、温度和时间等因素对反应的影响。结果表明,碳酸钾(K2CO3)具有较好的催化活性和选择性,反应最佳工艺条件为:常压,反应温度95℃,n(n-PrOH)∶n(DMC)=3∶1,w(K2CO3)=1%,反应时间5 h,DMC转化率95.9%,DPC产率73.7%。优化条件下的重复实验表明,该反应易于控制,重复性好。测定了常压下DPC和DMC的气液相平衡数据,结果表明,在常压下DPC和DMC二元物系不形成共沸物。     

Catalytic study on the transesterification of dimethyl carbonate and phenol to diphenyl carbonate

Transesterification of dimethyl carbonate and phenol to diphenyl carbonate and catalysts were investigated. The results showed that the transesterification was the reaction of soft base binding to hard acid, and hard acid catalysts had higher transesterification selectivity than the soft and border acid catalysts. When the hard acid n-Bu₂SnO and bases constituted acid–base complex catalysts, it was found that Cu₂O, as a promoter, could enhance the activity of n-Bu₂SnO outstandingly. The conversion of dimethyl carbonate was up to 50.8% with 99.9% transesterification selectivity. A plausible mechanism was also suggested.