甲烷氧化偶联制乙烯反应研究进展

乙烯是重要的化工基础原料,生产方式主要是石油裂解,随着石油资源的日益匮乏,寻找新的乙烯生产路线成为研究重点。我国天然气储量丰富,甲烷氧化偶联(OCM)制乙烯工艺路线得到研究者的广泛关注。OCM路线是能够替代石油资源生产烯烃的重要途径,也是高效清洁利用天然气的重要发展方向。本文综述甲烷氧化偶联制乙烯的反应过程以及催化剂类型,对不同类型催化剂的OCM性能进行对比,具体分析提高甲烷氧化偶联催化性能的关键因素,有利于推进OCM催化剂的研究进程。     

国内外乙烯生产工艺和催化剂研究进展

概述乙烯主要的生产工艺如蒸气裂解制乙烯、石脑油催化裂解制乙烯、重油催化裂解制乙烯、炼厂气干气制乙烯、C_4制乙烯、甲醇制乙烯、乙醇制乙烯、甲烷制乙烯、合成气制乙烯和生物法制乙烯等。主要比较工艺特点、反应机理、催化剂以及典型工艺等方面。认为由于原料的差异,煤基工艺发展相对较为成熟,石油基工艺发展相对缓慢,利用煤基乙烯生产工艺和催化剂将有助于开发石油基的工艺和催化剂。     

天然气制低碳烯烃研究进展

对当前低碳烯烃技术发展进行了简要介绍,并具体介绍了天然气甲烷氧化偶联制乙烯、合成气直接制乙烯和合成气经甲醇制乙烯技术的催化剂及工艺路线研究情况.为低碳烯烃技术的长远发展提供了参考.     

甲烷活化与转化的研究进展

甲烷活化与转化是当今催化研究领域的前沿课题。本文对甲烷氧化偶联制乙烯、甲烷芳构化、甲烷部分氧化制合成气的催化剂进行了介绍。     

天然气制乙烯技术的研究进展

简要介绍了天然气制乙烯的方法,主要讨论了甲醇制乙烯(MTO)及其催化剂的研究进展和甲烷氧化偶联制乙烯(OCM)及其催化剂的研究进展。     

甲苯甲烷氧化偶联制苯乙烯的研究

对甲苯甲烷氧化偶联制苯乙烯的工艺、催化剂、反应机理等方面的研究进展进行了评述，提出了今后研究的方向。     

国内外乙烯生产工艺的研究现状与展望

通过介绍乙烷脱氢,催化裂解,甲烷氧化偶联和甲醇转化及生物质乙醇脱水制乙烯等方法,阐述了乙烯制备的工业进展,并与传统催化裂解方法相比较,说明了其优缺点;分析了生物质乙醇脱水制乙烯原理与方法,生物质乙醇的来源,与其脱水制乙烯的优点以及国内外研究现状和发展前景。     

甲烷制乙烯技术研究进展

为了改变乙烯生产原料过分依赖于石油资源的状况,各国积极开展了对原油、生物资源、煤和甲烷等原料制乙烯新工艺的研究开发,乙烯生产原料多样化的趋势日渐明朗。对甲烷直接制乙烯技术——甲烷氧化偶联制乙烯和甲烷无氧催化制乙烯技术进行综述,并对其关键技术进行分析。     

天然气制乙烯技术进展及经济性分析

介绍了当前几种主要的天然气制乙烯技术新进展,包括天然气经甲醇制乙烯、费-托合成制乙烯、甲烷氧化偶联制乙烯技术进展及应用情况,并对这几种工艺进行了技术经济评价,结论认为:天然气制乙烯技术的大规模应用,主要取决于天然气原料供应的有效保障及其价格是否合理,在天然气供应充足、价格合理的条件下,天然气经甲醇制乙烯工艺将会得到较快发展,而费-托合成制乙烯、甲烷氧化偶联制乙烯技术目前尚未达到成熟应用阶段,需要持续加大研发力度,争取早日实现工业化应用。     

CO2氛围中低碳烷烃制烯烃催化剂的研究进展

CO₂作为温和的氧化剂有效抑制了低碳烷烃催化转化过程中深度氧化的发生,然而其广泛应用还依赖于高效、高稳定性催化剂的研究与开发。本文就近年来国内外有关利用CO₂作为氧化剂在低碳烷烃催化转化反应方面的研究成果进行了综述,主要涉及甲烷氧化偶联制乙烯和乙烷催化剂;乙烷氧化脱氢制乙烯催化剂、丙烷氧化脱氢制丙烯催化剂和丁烷氧化脱氢制丁烯催化剂,分析讨论了CO₂作为氧化剂的作用和作用机制,并提出了研究展望。     

Li~+/MgO上交叉偶联作用的研究

采用Li+/MgO催化剂研究了Li含量、反应温度、原料气组成对甲烷和甲苯催化氧化交叉偶联成乙苯或苯乙烯 (即C8)反应的影响 ,对几种Li含量催化剂上各影响因素引起的差异进行了考察。结果表明 ,其活性中心也主要是Li+O- ,合适的L酸点是本交叉偶联反应中反应物的吸附中心 ,Li+O- 和L酸点是决定偶联反应产物C2 和C8的主要因素。偶联可能主要按游离基机理进行     

Low temperature catalysts for oxidative coupling of methane

A simple review is given to the recent work of the oxidative coupling of methane at low temperature. Emphasis is laid on the different systems of low-temperature catalysts under conventional CH₄/O₂ co-feed conditions, and on the investigations of low-temperature oxidative coupling of methane in the presence of steam in the feed. Other approaches, e.g. oxidative coupling of methane at elevated pressure and moderate temperature, preparing ethylene by oxidative coupling reaction of methane on laser-activated solid surface, are also included.     

芳基二氢萘类木脂素的不对称合成研究进展

天然木脂素是由含酚羟基的苯丙素类化合物在生物酶催化下,通过氧化偶联反应而形成的。因此,以氧化偶联反应为关键步骤来仿生合成各类木脂素是最常用也是最快捷的合成途径。文章将就如何利用氧化偶联反应,在生物体外进行简单快捷的构建芳基萘类木脂素的基本骨架结构展开相关论述。     

Cold flow model and computer simulation studies of a circulating fluidized bed reactor for the oxidative coupling of methane

A circulating fluidized bed configuration has been developed for application in the oxidative coupling process. The configuration comprises a bottom turbulent fluidized bed, wherein the oxidative coupling reaction is conducted, followed by a reduced-diameter top fast bed for catalyst entrainment and hydrocarbon cracking. The hydrodynamic characteristics of this configuration have been investigated in a pilot-plant cold flow unit. Detailed experimental results on the turbulent bed flow structure and the gas phase residence time distribution are presented and discussed. The performanceofthe proposed reactor is analyzed by computer simulation studies based on a published oxidative coupling kinetic model. It is shown that improved hydrocarbon yields can be obtained by optimizing the hydrodynamic structure and the mixing characteristics of the turbulent bed.     

Dechlorination of chlorophenols mediated by carbon nanotubes in the presence of oxygen

Using chlorophenols as probe compounds, we examined the occurrence of oxidative coupling during carbon nanotube adsorption of phenolic compounds in the presence of oxygen. The oxidative coupling was confirmed by the agreement of the dechlorination stoichiometries of various chlorophenols with the free-radical mechanism of oxidative coupling. The oxidative coupling reaction was first-order with respect to chlorophenols on carbon nanotubes and increased with the increase of pH.     

甲烷氧化偶联反应的研究进展

通过对于甲烷氧化偶联法制取乙烯的反应过程中的各方面性能研究,对其进行具体分析,探讨针对不同性能的催化剂对于反应产物的各方面影响来进行具体分析。同时对于不同反应条件下的不同反应方面的影响也进行细致的研究分析,通过对于甲烷氧化偶联反应过程中的催化剂的催化机理进行研究。     

High yield synthesis of propanal from methane and air

High yield synthesis of propanal from methane and air can be obtained in a single pass at atmospheric pressure. Three catalytic processes are combined to give 13% yield of propanal based on total methane input. Ethene is made from the oxidative coupling reaction and carbon monoxide and hydrogen is generated from partial oxygenation of methane. These gases are combined and passed to a hydroformylation catalyst to give liquid propanal. The unreacted methane is inert in the hydroformylation stage, while oxygen deactivates the catalyst readily. The results imply that propanal can be obtained, in good yield, from methane and air provided that total oxygen conversion is achieved. The yield of propanal from the three combined processes can be substantially higher than that of ethene from the oxidative coupling reaction. Thus, higher yields of a condensible and oxygenated product are obtained.     

Investigations on a Ce/Li/MgO-Catalyst for the oxidative coupling of methane

The heterogeneously catalyzed oxidative coupling of methane into ethane and ethylene has been investigated using a Ce/Li/MgO catalyst. A tentative catalytic mechanism, which explains the role of cerium, is proposed and confirmed by pulsing experiments. The loss of lithium during pretreatment and under reaction conditions was determined. A correlation between the lithium loading of the catalyst and its C₂ production rate was found. The reaction scheme has been partly elucidated using C₂H₄/O₂N₂ as feed gas. It is shown that both homogeneous and heterogeneously catalyzed reaction steps are of great importance.     

Hetero-homogeneous processes involved in oxidative conversion of methane, ethane and hydrocarbon mixtures over basic oxides

The conversion, selectivities and yields of methane-oxygen and ethane- oxygen mixtures over Li/MgO catalysts have been compared. The differences which are observed are likely to be due to the much shorter life time of ethyl radicals which are rapidly transformed into ethylene, thus preventing subsequent heterogeneous deep oxidation. Data on the oxidative dehydrogenation of ethane over rare earth oxides are also reported. The insensibility of this reaction to the chemical nature of these solids contrasts with what is observed for the oxidative coupling of methane. This is also accounted for by the short life time of ethyl radicals. When mixing methane with another hydrocarbon, cross coupling occurs only if the hydrocarbon C---H bond strength is relatively small (propene, toluene) suggesting that radicals are involved. ¹³CH₄ experiments have shown that for the case of toluene, the reaction proceeds via the addition of a Cl block from CH₄. The selectivity of cross coupling compared to homo-coupling is also explained in terms of life time of radicals.