电促进甲烷偶联合成碳二烃研究进展

甲烷直接转化为烃类是天然气合理利用的方向,近20年来这方面的研究国内外十分活跃,本文综合评述了电促进甲烷偶联制碳二烃的主要研究进展。     

电促进甲烷偶联合成碳二烃研究进展

甲烷直接转化为烃类是天然气合理利用的方向,近20年来这方面的研究国内外十分活跃。本文综合评述了电促进甲烷偶联制碳二烃的主要研究进展。     

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。     

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。     

甲烷氧化偶联反应制乙烯的研究进展

介绍了近年来甲烷氧化偶联制乙烯(OCM)过程的催化剂、反应机理、动力学及工程放大涉及的反应工艺、反应器等方面的研究进展,对甲烷氧化偶联法和传统裂解法的经济性进行了对比,指出目前甲烷氧化偶联制乙烯工艺的选择性和转化率还较低,因此成本上比裂解制乙烯要高。最后,对催化剂、工程放大、生产流程和分离方案等方面的研究中存在的问题进行了分析。     

甲烷氧化偶联制乙烯反应催化剂的研究

本文用常压固定床流动反应装置进行甲烷氧化偶联制乙烯的反应。结果表明,LiCl/硅藻土、KOH-LiCl/TiO_2、Li_2CO_3/ZnO是较理想的催化剂体系。分别以C_2H_4和C_2烃收率为指标,使用0.5g催化剂,在温度770℃、气体流量CH_4:O_2:N_2为10.20:5.68:18.52ml/min条件下,其收率可达到17～19％和21～28％。另外,以XRD、IR对催化剂进行了表征,结果表明载体与活性组分间相互协同作用形成了较强的甲烷氧化偶联活性中心。     

甲烷氧化偶联制乙烯工艺研究进展

甲烷氧化偶联(OCM)途径是通过一步法获取乙烯,是现有乙烯生产中最为简捷的工艺。本文综述了该工艺催化剂系统、反应机理、工艺开发研究的新进展,并探讨了OCM过程面临的关键问题有催化剂的选择、反应器和反应流程的设计和反应温度的控制。     

甲烷氧化偶联制C2烃催化剂及催化反应机理研究进展

综述了甲烧氧化偶联制乙烷、乙烯催化剂及催化机理研究概况。重点介绍1989年以来对碱及碱土金属化合物、烯土氧化物、复合氧化物等各类催化剂的研究进展。对目前催化剂上甲烷活化途径、甲基自由基在反应过程中的作用机理、不同氧化物种及表面酸、碱位与催化性能的关系等方面的研究抉况及不同观点也作了简介。     

The synthesis of ethene during the oxidative coupling of methane

The effect of residence time on the selectivity of a MgO catalyst for the formation of ethene in the methane coupling reaction has been studied. It is found that the variation in ethene selectivity with this time follows opposite trends depending on the experimental conditions. In both cases the results show a positive intercept at zero residence time which may indicate that ethene is a primary product. However, calculations show that gas phase radical reactions just above the catalyst surface could account for the ethene observed even at very short residence times. It is concluded that experiments such as these cannot reliably distinguish between primary and secondary product formation. A SmOCl catalyst was studied and it was found that HCl was released when wet gases were passed over the catalyst at relatively low temperatures. It is concluded that much of the ethene produced over oxychloride catalysts may be produced by gas phase reactions involving chlorine radicals.Based in part on a paper given at the Royal Society-U.S.S.R. Academy Workshop on Catalysis and Surfaces, Oxford, April 8–10, 1989.     

合成3,4-二氢嘧啶-2-酮衍生物的研究进展

概述了近十年来三组分"一锅法"合成3,4-二氢嘧啶-2-酮衍生物的研究进展,分析了反应物种类、催化剂、溶剂及反应条件对3,4-二氢嘧啶-2-酮类化合物合成的影响,介绍了合成3,4-二氢嘧啶-2-酮衍生物的合成方法。     

吉非替尼合成研究进展

吉非替尼是一种新型抗肿瘤药物。本文综述了吉非替尼的合成方法及每种合成方法所用的原料、中间产物和过程。     

手性芳基醇的合成研究进展

综述了近年来手性芳基醇的合成研究情况,着重介绍了对羰基进行不对称加成来制取手性芳基醇的新进展。     

The enhancement of the oxidative coupling of methane on oxide/SiO2 catalysts by tetrachloromethane

The introduction of carbon tetrachloride to the feed stream in the conversion of methane to C₂ hydrocarbons over a variety of silica-supported oxides is shown to alter both the conversion and selectivity, but, notably with oxides of Ba, Cs and Mn produces remarkable increases in the yield and selectivity to C₂H₄ and C₂H₆, particularly the former.     

Oxidative coupling of methane to C2-hydrocarbons over La-promoted CaO catalysts

La₂O₃ promoted CaO [La/Ca (mol/mol) = 0.05] catalyst shows very high activity and selectivity (methane conversion: 25%, C₂-selectivity: 66% and C₂-space-time-yield: 864 mmol ·g^–1 (cat.)·h^–1) with no catalyst deactivation in oxidative coupling of methane to C₂-hydrocarbons at 800 ° C.     

煤层气脱氧剂的研究进展

阐述了燃烧脱氧、催化氧化、化学吸收法等3种脱氧机理,主要综述了贵金属、铜系、铁系、锰系、钼系以及多孔陶瓷材料等相关脱氧剂的制备工艺、脱氧原理和研究现状。通过对比不同脱氧剂的制备成本以及脱氧效果、后处理程序等,指出各种脱氧剂的优缺点。其中贵金属脱氧剂脱氧效果最好,但消耗甲烷、氢气等还原气体,且产生CO₂/H₂O等杂质;非贵金属脱氧剂价格低廉,但脱氧效果略差,使用温度相对较高;非金属型脱氧剂具有不易硫中毒等优缺点。最后,综合前述脱氧剂的特点,提出脱氧剂的两个发展方向,即非金属脱氧剂和具有较强吸附、催化性能的复合型脱氧剂。     

Optimal oxygen concentration strategy through an isothermal oxidative coupling of methane plug flow reactor to obtain a high yield of C2 hydrocarbons

An optimal oxygen concentration trajectory in an isothermal OCM plug flow reactor for maximizing C₂ production was determined by the algorithm of piecewise linear continuous optimal control by iterative dynamic programming (PLCOCIDP). The best performance of the reactor was obtained at 1,085 K with a yield of 53.9%; while, at its maximum value, it only reached 12.7% in case of having no control on the oxygen concentration along the reactor. Also, the effects of different parameters such as reactor temperature, contact time, and dilution ratio (N₂/CH₄) on the yield of C₂ hydrocarbons and corresponding optimal profile of oxygen concentration were studied. The results showed an improvement of C₂ production at higher contact times or lower dilution ratios. Furthermore, in the process of oxidative coupling of methane, controlling oxygen concentration along the reactor was more important than controlling the reactor temperature. In addition, oxygen feeding strategy had almost no effect on the optimum temperature of the reactor. Finally, using the optimal oxygen strategy along the reactor has more effect on ethylene selectivity compared to ethane.     

Remarkable enhancing effect of carbon dioxide on the conversion of methane to C2 hydrocarbons using praseodymium oxide

The presence of carbon dioxide remarkably enhanced the conversion of methane to ethane over praseodymium oxide in the absence of gaseous oxygen at 500–650°C. CO was simultaneously formed from CO₂ accompanying the conversion of methane. The oxygen vacancies in praseodymium oxide were suggested to play key roles in this low-temperature reaction. This revised version was published online in July 2006 with corrections to the Cover Date.