Synthesis of dimethyl carbonate by gas-phase oxidative carbonylation of methanol in the presence of solid catalyst I. Catalyst preparation and catalytic Properties

The gas-phase synthesis of dimethyl carbonate (DMC) from methanol, carbon monoxide and oXygen has here Studied in a flow system at atomspheric Pressure. A series of Catalyst used in this reaCtion have been prepared and evaluated. The influence of trivared carbon supporters, alkaline metal Promoters and operation conditions on DMC opthesis reaction has been discussed. Under the conditions of 130℃, CO/O2=1 .96, SV=3340h-1, the space-time yield (STY) of DMC over PdCl2-CuCl2-CH3COOK/ac. catalyst is 217g/l-cat h,which is higher than what is published in the literatUre so far.

Oxidative Carbonylation of Methanol to Dimethyl Carbonate Over Cu(Ⅱ)–1,10-Phenanthroline Bromide Complexes

In order to develop the catalysts with low corrosiveness for the oxidative carbonylation of methanol to dimethyl carbonate(DMC), Cu Br2 was selected as the metal source to prepare Cu coordination compounds, Cu(phen)Br2,[Cu(phen)2Br]Br and [Cu(phen)3]Br2(phen = 1,10-phenanthroline). These complexes were characterized by thermogravimetric analysis and temperature-programmed reduction. Their catalytic performances were investigated. It was found that the metal coordination environments and thermal stability of the complexes played an important role in their catalytic activities. Cu(phen)Br2exhibited the highest activity due to the lowest steric hindrance, the most positions occupied by the bromide ions and the highest thermal stability. The turnover number was up to 47.6 DMC mol·(Cu mol)-1with selectivity of 92.8% under conditions of 120 °C, ratio of partial pressure of CO to O2 of 19:1(below the explosion limit of CO) and catalyst concentration of 0.011 mol·L-1.Furthermore, a plausible reaction mechanism was suggested on the basis of the experimental data.

A Novel Sulfided Mo/C Catalyst for Direct Vapor Phase Carbonylation of Methanol at Atmospheric Pressure

The direct carbonylation of methanol, without any halide in the feed as apromoter, is presented. A series of Mo catalysts supported on activated carbon, γ-Al_2O_3 and SiO_2were prepared. The results show that the support greatly affects the Mo catalyst in the directvapor-phase carbonylation of methanol, and activated carbon is the best supports of the investigatedsupports. In addition, the relationships between adsorptions of NH_3 and CO and carbonylation ofmethanol were investigated. A novel sulfided Mo/C catalyst had high activity and selectivity for thevapor phase carbonylation of methanol to methyl acetate without the addition of a CH_3I promoter tothe feed. The reaction conditions were optimized at a reaction temperature of 573 K, a methanolconcentration of 23 mol% and a carbon monoxide space velocity of 3,000 L/(kg·h). Under theseoptimal conditions a methanol conversion of 50%, carbonylation selectivity of 80 rnol%, andspace-time yield of 8.0 mol/(kg·h) were obtained. The active phase of this novel sulfided Mo/Ccatalyst is the non-crystalline phase, and the active component is present as MoS_(2.5) on thesurface of the activated carbon.

Kinetics of Methanol Carbonylation to Methyl Formate Catalyzed by Sodium Methoxide

Kinetics of synthesis of methyl formate from carbon monoxide and methanol, using sodium methoxide as the catalyst and pyridine as the promoter in a batch reactor, was studied. Kinetic parameters such as the apparent reaction orders, the rate constant and the apparent activation energies were obtained. The experimental results showed that both the reaction orders with respect to CO and methanol equal to 1, the general reaction kinetic equation is (-r)=-dp(CO)/dt=k, p(CO).[MeOH], and the rate constant is k=8.82×10~6exp [-61.19×10~3/(R·T)] in the presence of pyridine. The apparent activation energies had decreased 6.44 kJ/mol and the rate constant had increased more than 1.5 times when pyridine was used as the promoter in the catalyst system.

STUDY OF CARBONYLATION OF METHANOL TO ACETIC ACID AND ACETIC ANHYDRIDE OVER A BIDENTATE POLYMER BOUND CIS-DICARBONYLRHODIUM COMPLEX AS CATALYST

Copolymer of 2-vinylpyridine and vinylacetate coordinated with dicarbonylrhodium used as a catalyst for carbonylation of methanol to acetic acid and anhydride has been studied. The structural characteristics of the copolymer ligand and complex, and the influences of the reaction conditions on the carbonylation catalyzed by this polymer complex have been investigated. In comparison with small molecule catalyst of Rh complex, the bidentate copolymer coordinated complex has better thermal stability. The reaction mechanism of the carbonylation reaction is also illustrated.

Efficient Nd Promoted Rh Catalysts for Vapor Phase Methanol Carbonylation

A Nd promoted-Rh catalysts supported on polymer-derived carbon beads for vapor-phase methanol carbonylation was developed. Rh-Nd bimetallic catalysts obviously have higher activity than that of supported Rh catalyst under similar reaction condition. The difference between the activity of above two catalyst systems is clearly caused by the intrinsic properties generated by the introduction of Nd.

KINETIC STUDY OF CARBONYLATION OF METHANOL TO ACETIC ACID AND ACETIC ANHYDRIDE OVER A NOVEL COPOLYMER-BOUND CIS-DICARBONYLRHODIUM COMPLEX

The kinetic study of carbonylation of methanol-acetic acid mixture to acetic acid and acetic anhydride over a cis-dicarbonylrhodium complex (MVM' Rh) coordinated with the ethylene diacrylate (M') crosslinked copolymer of methyl acrylate (M) and 2-vinylpyddine (V)shows that the rate of reaction is zero order with respect to both reactants methanol and carbon monoxide, but first order in the concentrations of promoter methyl iodide and rhodium in the complex. Polar solvents can accelerate the reaction. Activation parameters were calculated from the experimental results, being comparable to that of the homogeneous system. A mechanism similar to that of soluble rhodium catalyst was proposed.

A NOVEL COPOLYMER-BOUND CIS-DICARBONYLRHODIUM COMPLEX FOR THE CARBONYLATION OF METHANOL TO ACETIC ACID AND ACETIC ANHYDRIDE

A series of porous microspheres of linear and ethylene diacrylate (M') cross-linked copolymers of 2-vinylpyridine (V) and methyl acrylate (M) reacted with tetracarbonyldichlorodirhodium to form a series of cis-dicarbonylrhodium chelate complex (MVRh and MVM 'Rh). They are thermally stable yet very reactive in the carbonylation of methanol to acetic acid, and of methanol-acetic acid mixture to acetic acid and acetic anhydride with a selectivity of 100% under relatively mild and anhydrous conditions.

B/Al/Ga-MOR分子筛催化甲醇/二甲醚羰基化反应机理的理论计算研究

采用DFT计算比较分析了B、Al和Ga分别同晶取代MOR分子筛八元环侧袋T3位点及十二元环孔道T4位点时甲醇及二甲醚羰基化反应机制的共性及差异。研究发现,CO插入甲氧基生成乙酰基的反应遵循S_(N)2机制,且为羰基化反应过程中的决速步;473 K下,无论甲醇或二甲醚为原料,生成的乙酰基更倾向于与甲醇中的CH3O作用生成乙酸甲酯;T3位点具有更好的羰基化择形性,而T4位点上更倾向于发生由三甲基氧鎓离子生成芳烃导致催化剂失活的副反应。与Al-MOR相比,在T3位点引入B和Ga会导致羰基化反应能垒的升高,降低其催化性能;而在T4位点引入B和Ga(尤其是B)则可大幅提升其生成三甲基氧鎓离子的能垒,抑制芳烃生成过程,提升催化剂稳定性。本工作有助于认识MOR分子筛不同孔道内酸性位点发生同晶取代时催化羰基化反应机制的差异,为调控设计高效MOR沸石催化剂提供一定的理论支撑。

醋酸生产技术及对比

醋酸在石油化工生产过程中,是最基本的化工原料之一,占据着重要的位置。介绍了制备醋酸的多种工艺方法,并对每一种方法的优缺点进行了详细的阐述。同时,对目前被广泛使用的甲醇羰基法制备醋酸的BASF法、Monsanto/BP法、UOP/Chiyoda法工艺进行了详细介绍和比较,希望对各位从业者有所帮助。

铱/铑/钌复合催化剂催化甲醇羰基化合成醋酸的研究

随着醋酸行业竞争越来越激烈,降低生产成本以提高市场竞争力显得非常重要。研究了在保持催化活性的基础上采用价格相对低廉、稳定性较好的贵金属铱,钌来部分替代贵金属铑在羰基化合成醋酸中的可行性。

2-丙基庚醇生产过程中的收率影响因素分析

2-丙基庚醇是煤基甲醇制烯烃装置碳四组分的重要深加工产品,其产品收率和产量直接关乎企业的经济效益。介绍了国能包头煤化工有限责任公司2-丙基庚醇的生产工艺流程,分析了羰基合成戊醛过程中混合碳四组分组成、CO分压、催化剂浓度,缩合反应过程中反应温度、停留时间、碱浓度,加氢反应过程中反应温度、氢气质量等因素对中间品戊醛、2-丙基庚烯醛和最终产品2-丙基庚醇收率、产量的影响,并针对性地进行了优化和操作参数调整,不断提高2-丙基庚醇的收率和产量。

乙酸合成中铱基催化剂的研究进展与中毒因素的分析

甲醇羰基化制乙酸是一种重要的工业化学反应,铱基催化剂相对于铑基催化剂具有成本较低、生产工艺的水含量低、副产物丙酸生成较少等优点,然而存在着催化剂对杂质离子敏感度高与催化剂分离成本高等问题。以甲醇羰基化制乙酸中经典铱基催化剂的反应机理分析为重点,总结了引起铱基催化剂中毒的因素和新型铱基催化剂的设计与合成进展,旨在为甲醇羰基化制乙酸工艺的改进和优化提供重要的理论参考。

甲醇制乙酸工艺中降低杂质离子浓度的研究进展

乙酸是合成乙酸乙烯、乙酸酯、乙酸酐和氯乙酸等有机化合物的关键原料。甲醇羰基化制备乙酸是目前的主流工艺,然而在反应液中微量的杂质离子对催化剂的活性和稳定性产生重大的影响。以当前主流的Cativa工艺(铱基均相催化体系)为例,分析了杂质离子的来源及其对催化剂性能的负面影响。综述了当前采用的杂质离子处理策略,并着重介绍了离子交换树脂技术在杂质离子去除中的应用。从而为甲醇羰基化制备乙酸的正常生产提供一定的参考。

合成气绿色合成乙酸研究进展

相比于传统甲醇液相羰基化路线,合成气绿色合成乙酸具有环境友好、成本低等优势,具有广阔的发展前景。综述了合成气绿色合成乙酸路线和催化剂研究进展,阐述了催化剂设计优化策略,重点讨论了分子筛酸性和扩散性等性质对反应性能的影响规律。然后归纳了体系中H_(2)O含量、原料气n(H_(2))/n(CO)、活性组分接触距离、反应温度和反应压力等关键条件对反应性能的影响规律。总结认为,合成气绿色合成乙酸的关键过程为丝光沸石(MOR)分子筛催化甲醇羰基化制乙酸,调控增加MOR八元环酸性位数量和减小MOR颗粒尺寸以提高乙酸时空收率和催化剂稳定性是该过程研究的重点。本研究可为开发选择性高、应用条件温和和催化剂廉价易得的合成气绿色合成乙酸工艺提供一定参考。

碘化锂对甲醇羰基合成醋酸铱/钌催化体系的影响

介绍了甲醇羰基化合成醋酸过程中,在铑体系催化剂中添加碘化锂的作用机理及铱体系的催化机理。研究了在铱/钌体系中添加适量碘化锂对催化剂活性和稳定性的影响,并提出工业化应用的建议。

Novel fabrication of copper oxides on AC and its enhanced catalytic performance on oxidative carbonylation of methanol

Copper oxides（CuOx） nanoparticles dispersed on activated carbon（AC） were prepared by using vaporphase methanol as the reducing agent. The CuOx/AC as prepared exhibited an enhanced catalytic activity in oxidative carbonylation of methanol to dimethyl carbonate（DMC）. The catalytic performance was significantly influenced by reduction conditions including temperature and time. With the similar selectivity of DMC, the space time yield（STY） under optimal reduction conditions reached up to 408 mg g^-1h^-1, which is superior to conventional methods such as thermolysis and solvothermal reduction. Based on the characterization results of XRD, TEM and XPS, the good copper dispersion and high Cu^＋ content obtained by vapor-phase methanol reduction were mainly responsible for the high catalytic activity.

Oxycarbonylation of methanol over modified CuY: Enhanced activity by improving accessibility of active sites

CuY zeolite is a promising catalyst in the field of manufacturing dimethyl carbonate(DMC) through oxidative carbonylation of methanol. Cu^+ exchanged with Br?nsted acid sites are supposed to be active for this reaction. However, the location of Cu^+ in small cages can not interact with reactants because of steric hindrance, which lead to a waste of Cu species. In this work, NH_4F solution was used to modify the pore structure of zeolite Y by etching the framework T atoms. Physical and chemical adsorption of probe molecules with different size are used to determine the changes of porosity as well as the accessibility of Cu^+ sites. At an optimized etching time, the small cages were opened with maintained zeolitic framework. As a result, more Cu^+ species located in small cages become accessible to reactants, which contributes to the enhanced activity in this reaction.