Oxidative gas phase carbonylation of methanol to dimethyl carbonate over chloride-free Cu-impregnated zeolite Y catalysts at elevated pressure

Incipient wetness impregnation of zeolite Y with copper(II) nitrate solution and inert activation at 650 °C led to active catalysts for the oxidative carbonylation of methanol to dimethyl carbonate in the gas phase. Activities were measured under elevated pressure (0.4–1.6 MPa) with feed compositions of CO/MeOH/O₂ = 40/20/6–1.5 vol.% (balanced by N₂) over zeolite Y loaded with 10–17 wt.% copper. It could be shown that inert activation at 650 °C enhanced the activity, and that Cu loading of 14–17 wt.% gave the best performance. By combined XRD, TEM, TPR and DRIFT characterization it was found that the inert activation initiated dispersion of crystalline CuO, auto-reduction of Cu²⁺ to Cu⁺ and redistribution of copper ions with enrichment inside the supercages of the zeolite. The O₂ content of the feed was found to control the selectivity to dimethyl carbonate. Dimethyl carbonate selectivities of 70–75% were achieved within the temperature range of 140–170 °C at an O₂ content of 1.5 vol.%. This allowed space-time yields of dimethyl carbonate up to 632 g l_cat⁻¹ h⁻¹ at methanol conversions of 5–12%. Formation of the main side product, dimethoxymethane, was surprisingly affected by CO, which is not in line with suggested reaction pathways. A mechanism is proposed including formation of surface carbonate structures as common intermediate.     

甲醇氧化羰基化制碳酸二甲酯研究进展

碳酸二甲酯是重要的有机合成中间体,相对于传统的生产方式,通过甲醇氧化羰基化法制备碳酸二甲酯具有高效和环保等优点。综述液相法、直接气相法及间接气相法3种不同生产工艺路线及使用的催化剂,通过对比分析指出各自的特点和发展趋势。     

甲醇液相氧化羰基化合成碳酸二甲酯反应工艺条件研究

采用固态离子交换法制备SiO2-TiO2复合氧化物负载铜催化剂STCu(Ⅰ),在间歇反应装置中进行甲醇液相氧化羰基化合成碳酸二甲酯反应研究.优化的反应条件为催化剂质量浓度0.04 g/mL、反应时间90 min、反应温度140℃、压力3.6 MPa、CO/O2进料比3、搅拌速率700 r/min.各因素对反应结果影响的顺序为压力＞温度＞进料比＞转速.     

甲醇气相氧化羰基化合成碳酸二甲酯研究进展

介绍了气相直接法和气相间接法的工艺特点,比较了各类活性催化剂的结构特征及其催化性能。分析认为,气相间接法的关键是有效控制第一步反应并确保剧毒NO气体的安全循环使用;气相直接法避免了NO有毒气体的使用。评述了固态离子交换法制备的铜分子筛在气相直接法合成DMC反应中表现出比负载型CuCl2催化剂和Wacker型催化剂更高的稳定性以及较低的腐蚀性,但受分子筛表面酸位的限制,存在交换容量低,残余CuCl难以脱除的不足;而浸渍法制备的无Cl型铜分子筛对DMC的选择性较低;硅基复合氧化物通过改变制备条件可以有效控制表面B酸位的数量、强度及其分布,是基于固态离子交换反应原理制备负载铜催化剂的理想载体材料,值得关注。     

铜基催化剂的研究进展

综述了近年来甲醇直接气相氧化羰基化合成碳酸二甲酯的铜基催化剂由含氯催化剂、低氯催化剂到完全无氯催化剂的研究进展,总结了各类催化剂的结构特征、催化性能及存在问题,并指出催化剂的发展趋势和应用前景。     

甲醇氧化羰基化合成碳酸二甲酯反应机理研究进展

传统催化剂催化甲醇氧化羰基化合成碳酸二甲酯（DMC）因氯离子的存在易导致腐蚀、失活,通过负载、添加助剂或配体的铜催化体系可改善上述问题。本文介绍了各改进催化体系,并综述了其反应机理。其中负载CuCl2或CuCl催化剂的活性中间体是Cu(OCH3)Cl或Cu2(OH)3Cl;亚铜与配体混合时,配体的种类、数量、结构等会影响甲氧基铜物种的形成;固体离子交换得到的Cu-分子筛催化剂实现了无氯化,然而活性较低;将Si、Al、Ti等氧化物作为载体时,对载体表面结构的改性改善了催化性能。大多数铜催化体系的控制步骤为CO对甲氧基铜物种的插入反应,然而对于甲氧基铜物种的产生以及CO对甲氧基铜物种插入后的产物仍存在分歧。指出进一步研究各催化体系的反应机理仍然是今后工作的重点。     

甲醇氧化羰基化合成碳酸二甲酯催化剂研究进展

碳酸二甲酯(DMC)是一种重要的绿色有机合成中间体。在合成DMC的方法中,甲醇氧化羰基化法对设备腐蚀小、原料易得、产物易分离,有着诱人的工业化前景。文中介绍了该反应中所使用的Co、Pd、Cu和Au这4类催化剂的结构特点和催化性能,比较了不同催化剂在氧化羰基化中的催化效果。为了进一步提高催化剂的活性、选择性、减少其腐蚀性,开发出性能更好的工业催化剂,可以通过研究催化反应机理,并通过添加助剂和载体来实现。其中无卤铜系催化剂是今后羰基化合成DMC的重要研究方向。     

High selective catalyst CuCl/MCM-41 for oxidative carbonylation of methanol to dimethyl carbonate

In this study, MCM-41 material was synthesised and the mesoporous structure was confirmed by powder XRD patterns. Organic group 3-chloropropyl was anchored on the surface of MCM-41(∞) by reaction of 3-chloropropyltrimethoxysilane with terminal silanol groups on the surface of MCM-41(∞) material. The modified material MCM-41(∞)-Cl still kept its mesoporous structure even after the material was calcined again at 550°C for 4 h and the organic groups were removed. Prepared by solid state ion-exchange under flowing nitrogen, CuCl/MCM-41 catalyst had 100% selectivity of dimethyl carbonate based on methanol and 5–10 wt.% conversion of methanol at 130°C. With the decreasing mole ratio of Si/Al of MCM-41 material, e.g. increasing the aluminium content in the material, the catalytic activity increased because more Cu^I was loaded on the material. When the reaction temperature increased, the dimethyl carbonate selectivity decreased and three by-products: dimethyl ether, methyl formate, dimethoxymethane were formed at high temperature. Finally increasing the oxygen partial pressure in the feed gases resulted in more dimethyl carbonate formed.     

甲醇氧化羰基化合成碳酸二甲酯铜基催化剂的研究进展

碳酸二甲酯的合成是近年来国内外的一个研究热点。综述了碳酸二甲酯的合成工艺及催化剂,尤其是Cu基催化剂的研究进展,深入探讨了甲醇氧化羰基化反应中载体和助剂对Cu基催化剂活性和选择性的影响。     

吡啶-2-羧酸钴的制备及催化羰化性能研究

席夫碱与金属离子形成的配合物是一类重要的均相氧化、羰化、聚酮反应催化剂 [1～ 3] ,其中吡啶 - 2 -羧酸是重要的螯合物配体 ,它与各种金属生成的吡啶 - 2 -羧酸盐在室温及氧化环境下仍很稳定 ,对许多反应具有催化性能 ,例如与钒生成的化合物是乙烯的环氧化反应和苯的羟基化反应的催化剂。制备吡啶 - 2 -羧酸有多种方法 [4,5 ] ,其中用高锰酸钾氧化 2—甲基吡啶法最为简便。本文采用此法合成了吡啶 - 2 -羧酸 ,并与碳酸钴反应制备了吡啶 - 2 -羧酸钴螯合物 [6 ]。结合我们前期对氯化亚铜催化剂合成碳酸二甲酯 (以下称 DMC)的研究结果 [7…     

羰基合成碳酸二甲酯的研究进展

简述了分别以一氧化碳、二氧化碳与甲醇、二甲醚等进行羰基化反应合成碳酸二甲酯(DMC)的研究进展。并分别对各种工艺路线进行了分析和评价。目前现有几种工艺的不足之处表现在:甲醇氧化羰化中催化剂活性低、易失活、难以再生;催化剂使用时反应物转化率低;催化剂制备工艺复杂;反应工艺条件苛刻;CO2活化困难。最后阐述了碳酸二甲酯合成工艺的研究重点和发展前景。     

二甲醚羰基化催化剂的烧炭再生

以水热合成的H-MOR分子筛催化剂,通过对二甲醚羰基化反应失活后催化剂进行再生,考察了不同再生气体、再生温度、O₂体积分数、烧炭升温速率等条件,烧炭后催化剂上二甲醚羰基化活性性能。TPO表征结果表明：反应后H-MOR分子筛上有两种不同性质的积炭。积炭催化剂在3%（体积） O₂/N₂气氛中,从室温以2℃·min^-1升温至320℃恒温一段时间,然后以相同速率升温至550℃进行烧炭,再生催化剂活性几乎完全恢复。NH₃-TPD和BET表征结果表明,再生催化剂活性得以恢复是因为优化了烧炭方案,分子筛表面积炭能够被烧除干净同时分子筛孔道不被破坏。     

甲醇液相氧化羰基化合成碳酸二甲酯催化剂的研究进展

介绍和比较了甲醇液相氧化羰基化合成碳酸二甲酯各类催化剂的结构特点及其催化性能,认为选择无Cl的活性组分可以从根本上解决现有催化剂存在的失活和设备腐蚀问题,是新一代催化剂的发展方向;基于CuⅠ活性位特征进行催化剂设计与制备,有效控制活性位的数量、分布和落位,提高分散均匀度,进而调节催化剂的化学表面结构可望获得理想的催化性能。     

Ionic liquid as an efficient promoting medium for synthesis of dimethyl carbonate by oxidative carbonylation of methanol

The synthesis of dimethyl carbonate by oxidative carbonylation of methanol using Cu salt catalysts in the presence of various room temperature ionic liquids (RTILs) was reported. Among the ionic liquids used, N-butylpyridinium tetrafluoroborate was the most effective promoter in terms of the conversion of methanol and the selectivity to dimethyl carbonate (DMC). The influences of reaction temperature, pressure, time, molar ratio of CO/O₂, and amount of the ionic liquid on the oxidative carbonylation of methanol were investigated. The results indicated that under the reaction conditions of 120 °C and 2.4 MPa of a 2:1 mixture of CO and O₂, 17.2% conversion of methanol, 97.8% selectivity of DMC and a DMC productivity of 4.6 g g⁻¹ cat h⁻¹ were achieved. The N-butylpyridinium tetrafluoroborate-meditated CuCl catalyst system could be reused at least five recycles with the same selectivity and a slight loss of catalytic activity due to loss of the catalyst during handling and transferring the reaction mixture.     

甲醇羰基合成碳酸二甲酯反应机理及多相催化剂研究进展

针对甲醇羰基合成碳酸二甲酯（DMC）反应体系,在综合分析以氯化亚铜、氯化铜以及铜分子筛为催化剂的氧化羰基化反应机理的基础上,着重介绍了多相催化剂的种类、结构、活性中心以及制备工艺的研究进展,并对各类催化剂的催化性能进行了分析和评价。通过溶胶-凝胶技术和分子筛包覆的方法制备的钴系催化剂,其活性和稳定性得到了提高;钯铜系催化剂经过载体改性和加入适当的助剂,甲醇转化率增大并在一定程度上抑制了氯离子的流失;无氯铜系催化剂避免了对设备的腐蚀,但催化活性和DMC的选择性普遍较低。最后指出利用各种现代表征手段以及分析技术研究表面过程深刻了解甲醇羰基合成机理,才能在催化剂的设计和开发上取得创新和突破。     

甲醇液相氧化羰基化合成碳酸二甲酯催化剂的研究进展

甲醇液相氧化羰基化合成碳酸二甲酯(DMC)的催化类型主要有铜负载型、钴配合物型和钯铜复合型三种。其中铜负载型CuCl催化体系已经工业化,但由于Cl^－的丢失而引起催化剂活性的下降及反应生成的盐酸对设备腐蚀等,需要采取添加配位体或助剂稳定Cl^－或取代Cl^－等方法来解决。取代Cl^－是一种新的研究方向,具有工业应用前景。     

Influence of dehydrating agents on the oxidative carbonylation of methanol for dimethyl carbonate synthesis over a Cu/Y-zeolite catalyst

The influence of the dehydration by metal oxides on the synthesis of dimethyl carbonate(DMC) via oxidative carbonylation of methanol was studied. A Cu/Y-zeolite catalyst was prepared by the ion exchange method from CuCl_2·2 H_2O and the commercial NH_4-form of the Y type zeolite. The catalyst was characterized by X-ray fluorescence(XRF), N_2 adsorption(BET method), X-ray diffraction(XRD), and temperature-programmed desorption of ammonia(NH_3-TPD) to evaluate its Cu and Cl content, surface area, structure, and acidity. Reaction tests were carried out using an autoclave(batch reactor) for 18 h at 403 K and 5.5 MPa(2CH_3OH + 1/2O_2+CO?(CH_3O)_2CO + H_2O). The influence of various dehydrating agents(ZnO, MgO, and CaO) was examined with the aim of increasing the methanol conversion(X_(MeOH), MeOH conversion). The MeOH conversion increased upon addition of metal oxides in the order CaO MgO ZnO, with the DMC selectivity(SDMC) following the order MgO CaO ZnO. The catalysts and dehydrating agents were characterized before and after the oxidative carbonylation of methanol by thermogravimetric and differential thermogravimetric(TG/DTG), and XRD to confirm that the dehydration reaction occurred via the metal oxide(MO + H_2O → M(OH)_2). The MeOH conversion increased from 8.7% to 14.6% and DMC selectivity increased from 39.0% to 53.1%, when using the dehydrating agent CaO.     

LiF/CaO催化碳酸乙烯酯与甲醇合成碳酸二甲酯

以碳酸乙烯酯和甲醇为原料,用浸渍法制备了LiF/CaO催化剂,考察了该催化剂在碳酸乙烯酯(EC)与甲醇酯交换反应制备碳酸二甲酯(DMC)中的催化性能。用X射线衍射、N₂低温吸附和哈米特滴定等对催化剂进行了表征。结果表明,催化剂LiF/CaO在焙烧后生成新相CaF₂和Li₂O。在LiF负载量为20%(相对于CaO的质量)、焙烧温度为500℃、甲醇与EC物质的量比为10∶1、催化剂用量为碳酸乙烯酯质量的0.1%、反应温度70℃、反应时间为0.5 h的条件下,EC转化率、DMC选择性和收率分别为77.98%、99.97%和77.96%。     

尿素醇解法制备碳酸二甲酯

在对国内外合成碳酸二甲酯的研究状况综合分析的基础上,着重介绍了一种新的合成碳酸二甲酯的方法,即以甲醇和尿素为原料、以有机锡为催化剂的尿素醇解法.详细讨论了该方法所涉及的催化剂制备、反应机理、生产工艺和技术特点,指出尿素醇解法制备碳酸二甲酯是一种绿色化工生产工艺,具有广阔的发展前景.     

碳酸二甲酯-甲醇共沸物的吸附分离

分别采用疏水硅沸石Si-1和高硅HZSM-5分子筛吸附剂,对碳酸二甲酯(DMC)-甲醇(MeOH)气相共沸物进行动态吸附分离的实验研究。实验结果表明:疏水硅沸石Si-1及高硅HZSM-5分子筛均选择性吸附DMC,且表现良好的吸附分离性能。其中Si-1对DMC的吸附选择性达86%,100 g吸附剂对DMC的饱和吸附质量为3.48 g,分离因子α为14.77。此外,利用红外光谱分析了疏水硅沸石Si-1和高硅HZSM-5分子筛的特性基团,并采用热重分析对吸附饱和的吸附剂进行吸附机理研究。结果表明:HZSM-5分子筛含Si—OH和H+强吸附位,DMC在其上的吸附为强化学吸附;而DMC在硅沸石上的吸附是选择性物理吸附。