甲烷脱氢偶联制芳烃催化剂研究进展

综述了甲烷脱氢偶联制芳烃催化剂的研究进展 ,讨论了催化剂的影响因素 ,并介绍了甲烷脱氢偶联制芳烃的反应机理的研究进展     

镍基双金属催化剂上甲烷脱氢反应的密度泛函理论

为了从原子尺度上研究双金属的作用机理,采用基于密度泛函理论的第一性原理方法研究了甲烷在Ni-Pt和Ni-Pd双金属催化剂上的脱氢过程。计算结果表明,在Ni催化剂中引入Pt或Pd会大大减弱表面C原子的吸附,从而提高催化剂的抗积炭能力,而且甲烷第一步脱氢活化能会有所提高,反应活性略有降低。     

甲烷无氧脱氢芳构化反应最新研究进展

与甲烷的临氧转化相比,在无氧条件下将甲烷转化为芳烃具有独特的优势。本文从催化剂的筛选、反应体系的优化、活性组分与载体的相互作用及反应机理的探讨等方面综述甲烷无氧脱氢芳构化反应的最新研究结果。     

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。     

甲基环己烷脱氢催化剂研究进展

综述了甲基环己烷脱氢用非贵金属催化剂和含贵金属催化剂的研究进展,其中含贵金属催化剂是近几年的研究重点.提高脱氢催化剂在低温下的高活性将是甲基环己烷脱氢催化剂的主要研究方向.     

低温下花球状Ni/CeO_2催化剂上甲烷水蒸气重整制氢研究

利用水热法制备花状CeO_2,采用浸渍热分解法制备NiO/CeO_2催化剂,NiO纳米颗粒均匀地分布在CeO_2花瓣上,达到了高度的分散,增加了甲烷和水脱氢作用的活性位点。通过XRD、SEM对催化剂进行表征。甲烷水蒸气重整结果表明,该催化剂低温下表现了良好的活性,较高的转化率,较好的稳定性和理想的抗积炭能力。催化剂稳定性超过300 h,550℃时甲烷转化率达到95%。不同水碳比下的催化性能测试结果表明,1.5~2.5的低水碳比为该催化剂的理想范围。因此,该催化剂在低温甲烷水蒸气重整制氢上表现良好,是一种很具潜力的催化剂。     

CH_4-CO_2催化重整制合成气Co-MgO/活性炭催化剂的制备及性能

利用固定床反应装置研究了催化剂Co/活性炭(AC)中引入助剂Mg O对甲烷二氧化碳重整制合成气催化剂性能的影响,并通过XRD、SEM和BET技术对催化剂进行了表征。结果表明,添加适量的助剂Mg O一方面与活性物质发生协同作用,提高催化剂的比表面积;另一方面可以调节催化剂的酸碱性,提高催化剂对CO2的吸附活化,从而促进甲烷的裂解脱氢。400℃焙烧条件下制备的催化剂Co-Mg O/AC表现出最佳的催化活性和稳定性,在900℃下连续运行1 200 min,甲烷和二氧化碳转化率分别维持在96.7%和97.0%左右。     

甲烷催化燃烧与十二烷脱氢反应的间接热耦合

将甲烷催化燃烧的Pd-Zr/SBA-15/Al2 O3/FeCrA1金属整体式催化剂和十二烷催化脱氢的Pt-Sn-Li/Al2 O3/FeCrA1金属整体式催化剂分别填充在套管式反应器的内管和环隙中,在电炉伴温条件下研究了这两个反应的热耦合.实验结果表明,炉温略低于催化剂床层温度,说明吸热反应所需的热量来源于放热反应,...     

乙苯脱氢反应器压降升高的原因及影响

本文简述了乙苯脱氢反应器与"三合一"换热器的"π-L"结构布置型式及脱氢反应的反应条件,介绍了脱氢反应压降的变化情况,分析了压降变化的原因主要有催化剂破碎、催化剂表面积炭、催化剂表面钾盐析出和催化剂堆密度过大等.脱氢反应器压降升高对脱氢反应的影响,主要体现在反应副产物增加、能耗上升以及聚合风险增大等方面.因此,要尽量控...     

信息与动态

法开发甲烷转化制烷烃新型催化剂　　法国国立科学研究中心、里昂理化和电子大学以及BP公司研究人员发现 ,在其开发的多相催化剂作用下 ,甲烷可在相对低温的条件下转化成较高级烃类。他们认为负载在二氧化硅上的亲电子钽复合催化剂有利于烷烃的合成。采用表面有机金属法制备的新型催化剂 ,可在 2 5 0℃下将甲烷和丙烷混合物转化成乙烷 ,选择性接近 10 0 %。该项研究表明甲烷可取代氢气以打开C—C键 ,从而节约成本 ,且对环境友好。另外该新型催化剂提供了一条人们探索已久的甲烷直接转化成有价值产品的方法。甲烷是天然气中含量丰富但不活…     

典型二氧化碳利用技术的低碳成效综合评估

面向全新的碳中和愿景,二氧化碳利用作为一种重要的低碳技术,受到了学术界和工业界的广泛关注,开展技术的低碳成效评估对于技术研发及布局的顶层设计具有重要意义。然而已有研究主要基于技术特征开展定性的优先序判断,缺乏系统性的评估方法。本文首先对国内外二氧化碳利用技术发展现状开展梳理,围绕技术特性、碳中和效应、经济效应和社会效应四个方面,采用层次分析和目标趋近相结合的方法,构建了针对二氧化碳利用技术低碳成效综合评估的方法学;并对我国典型的二氧化碳利用技术低碳成效现状以及未来潜力开展应用评估,通过不同二氧化碳利用技术低碳成效的横向对比以及技术不同阶段低碳成效的纵向对比,研究发现：目前我国二氧化碳利用技术低碳成效整体水平偏低,不同二氧化碳利用技术低碳成效的差异主要来自技术特性和碳中和效应两大方面;我国现有的典型二氧化碳利用技术中,二氧化碳加氢合成甲醇技术和二氧化碳与甲烷重整制备合成气技术的低碳成效相对显著;通过对未来不同阶段二氧化碳利用技术低碳成效的对比分析,发现不同二氧化碳利用技术的低碳成效变化有较大差异,其中二氧化碳矿化养护混凝土和二氧化碳光电催化转化技术的低碳成效有明显提升。     

Hydrogenation of carbon dioxide and carbon monoxide over supported rhodium catalysts under 10 bar pressure

The hydrogenation of carbon dioxide and carbon monoxide was carried out in a 10-atm flow reactor over supported rhodium catalysts. Rh/ZrO₂ and Rh/Nb₂O₅ showed the highest activity for carbon dioxide and hydrogenation, the main product being methane. Methanol was formed selectively from carbon dioxide hydrogen over a Rh/TiO₂ catalyst. The products of carbon monoxide hydrogenation over supported Rh catalysts contained higher hydrocarbons and ethanol. The rate of C-C bond formation was higher in carbon monoxide hydrogenation than in carbon dioxide hydrogenation. The effect of the support on hydrogenation of carbon dioxide and carbon monoxide is discussed.     

Co-generation of synthesis gas and C2+ hydrocarbons from methane and carbon dioxide in a hybrid catalytic-plasma reactor: A review

The topics on conversion and utilization of methane and carbon dioxide are important issues in tackling the global warming effects from the two greenhouse gases. Several technologies including catalytic and plasma have been proposed to improve the process involving conversion and utilization of methane and carbon dioxide. In this paper, an overview of the basic principles, and the effects of CH₄/CO₂ feed ratio, total feed flow rate, discharge power, catalyst, applied voltage, wall temperature, and system pressure in dielectric-barrier discharge (DBD) plasma reactor are addressed. The discharge power, discharge gap, applied voltage and CH₄/CO₂ ratio in the feed showed the most significant effects on the reactor performance. Co-feeding carbon dioxide with the methane feed stream reduced coking and increased methane conversion. The H₂/CO ratio in the products was significantly affected by CH₄/CO₂ ratio. The synergism of the catalyst placed in the discharge gap and the plasma affected the products distribution significantly. Methane and carbon dioxide conversions were influenced significantly by discharge power and applied voltage. The drawbacks of DBD plasma application in the CH₄–CO₂ conversion should be taken into consideration before a new plausible reactor system can be implemented.     

等离子体技术在催化反应中的应用

本文介绍了一些等离子体技术在催化剂的制备，再生和改性等的应用；及等离子体技术在稳态分子甲烷，二氧化碳等化学利用上的一些研究进展。     

Partial Oxidation of Methane Catalyzed by H-Mordenite and Fluorinated Mordenite

Mordenite and fluorinated mordenite are compared as catalysts for the partial oxidation of methane in the temperature range 350–425°C. With both catalysts the major product is ethylene but the latter catalyst yields higher conversions up to 425°C at which temperature carbon monoxide and carbon dioxide become the primary products. Eliminating the oxidant, nitrous oxide, lowers the methane conversion but produces mainly ethane and ethylene. The oligomerization of methane without an oxidizing agent suggests that CH bond cleavage can result from protonation by superacid centers of the fluorinated mordenite.     

CH4和CO2在活性炭微球内扩散系数的测定

活性炭微球是一种储存及净化天然气的新型碳材料.采用高精度的重力分析仪(IGA-003, HIDEN)对天然气主要成分CH₄和CO₂杂质在活性炭微球材料内的扩散性质进行了研究.运用Fick扩散模型关联得到了CH₄及CO₂在活性炭微球内的扩散系数.研究结果表明,CH₄与CO₂在活性炭微球内的扩散属于晶体扩散,二者的扩散系数处于10^-13m²·s^-1数量级上.同时,CH₄与CO₂在介孔活性炭微球内的扩散速率均随着温度的增加而增加,随着体系平衡压力的增加而减小,而且CH₄的扩散速率要略大于CO₂的扩散速率.研究结果可用于活性炭微球吸附剂应用中传质性质的计算.     

气体在石墨化炭黑上吸附平衡的普遍化模型

通过静态容积法测试了CO2和CH4在石墨化炭黑上的吸附平衡数据,温度范围253.2～313.2 K,压力范围0～4.5 MPa.利用Virial方程计算CO2和CH4吸附平衡的亨利常数K,绘制(K·p)-n的普遍化曲线.结果表明,普遍化曲线可以很好地描述不同温度下CO2和CH4的吸附平衡数据,利用普遍化模型能够实现预测...     

Methane and carbon dioxide in dual-porosity organic matter: Molecular simulations of adsorption and diffusion

Shale gas, which predominantly consists of methane, is an important unconventional energy resource that has had a potential game-changing effect on natural gas supplies worldwide in recent years. Shale is comprised of two distinct components: organic material and clay minerals, the former providing storage for hydrocarbons and the latter minimizing hydrocarbon transport. The injection of carbon dioxide in the exchange of methane within shale formations improves the shale gas recovery, and simultaneously sequesters carbon dioxide to reduce greenhouse gas emissions. Understanding the properties of fluids such as methane and methane/carbon dioxide mixtures in narrow pores found within shale formations is critical for identifying ways to deploy shale gas technology with reduced environmental impact. In this work, we apply molecular-level simulations to explore adsorption and diffusion behavior of methane, as a proxy of shale gas, and methane/carbon dioxide mixtures in realistic models of organic materials. We first use molecular dynamics simulations to generate the porous structures of mature and overmature type-II organic matter with both micro- and mesoporosity, and systematically characterize the resulting dual-porosity organic-matter structures. We then employ the grand canonical Monte Carlo technique to study the adsorption of methane and the competing adsorption of methane/carbon dioxide mixtures in the organic-matter porous structures. We complement the adsorption studies by simulating the diffusion of adsorbed methane, and adsorbed methane/carbon dioxide mixtures in the organic-matter structures using molecular dynamics.     

Oxidative reforming of methane on structured Ni-Al<Subscript>2</Subscript>O<Subscript>3</Subscript>/cordierite catalysts

The catalytic properties of Ni/Al₂O₃ composites supported on ceramic cordierite honeycomb monoliths in oxidative methane reforming are reported. The prereduced catalyst has been tested in a flow reactor using reaction mixtures of the following compositions: in methane oxidation, 2–6% CH₄, 2–9% O₂, Ar; in carbon dioxide and oxidative carbon dioxide reforming of methane, 2–6% CH₄, 6–12% CO₂, and 0–4% O₂, and Ar. Physicochemical studies include the monitoring of the formation and oxidation of carbon, the strength of the Ni-O bond, and the phase composition of the catalyst. The structured Ni-Al₂O₃ catalysts are much more productive in the carbon dioxide reforming of methane than conventional granular catalysts. The catalysts performance is made more stable by regulating the acid-base properties of their surface via the introduction of alkali metal (Na, K) oxides to retard the coking of the surface. Rare-earth metal oxides with a low redox potential (La₂O₃, CeO₂) enhance the activity and stability of Ni-Al₂O₃/cordierite catalysts in the deep and partial oxidation and carbon dioxide reforming of methane. The carbon dioxide reforming of methane on the (NiO + La₂O₃ + Al₂O₃)/cordierite catalyst can be intensified by adding oxygen to the gas feed. This reduces the temperature necessary to reach a high methane conversion and does not exert any significant effect on the selectivity with respect to H₂.     

Mathematical model of formation of carbon dioxide hydrate upon injection of carbon dioxide into a methane hydrate stratum

A mathematical model of formation of carbon dioxide gas hydrate upon injection of warm carbon dioxide into a natural stratum saturated with methane and methane hydrate has been presented. The case when methane hydrate decomposes into gas and water on two frontal boundaries and the subsequent formation of carbon dioxide hydrate from carbon dioxide and water has been discussed. The regions where this mode is implemented depending on stratum permeability have been studied based on the pressure–temperature plane of the gas being injected into the stratum.