The role of the catalysts with highly dispersed and isolated active sites in the selective oxidation of light hydrocarbons

This review summarizes the role of catalysts with highly dispersed and isolated active sites (active sites: supported atoms f≤0.5%) in the selective oxidation of light hydrocarbons, such as methane, ethane and propane, into oxygenates and the epoxidation of olefins. The plausible structures of the highly dispersed and isolated active species, as well as their effects on the catalytic performances are discussed. The special physico-chemical properties and the functional mechanism of the catalysts with highly dispersed and isolated active sites, as well as the preparation, characterization of the catalysts with highly dispersed and isolated active sites and their applications in other types of reactions of lower hydrocarbons are summarized.     

不同Co—ZSM-5分子筛上的乙烷氨氧化反应性能

制备了各种Co—ZSM-5分子筛催化剂，通过XRD，SEM，BET等表征手段对样品进行了表征，并考察了其乙烷氨氧化反应性能。结果显示，样品的Si／Al比、分子筛晶粒尺寸及催化剂制备方法对乙烷氨氧化反应性能有较大影响。     

活性Al2O3负载Mn-Ce氧化物催化分子氧选择氧化醇类研究

以硝酸锰和硝酸铈为锰源和铈源采用湿法浸渍法制备了不同锰铈比的γ-Al2O3负载Mn-Ce氧化物催化剂．实验结果表明,该催化剂能够有效催化以分子氧为氧化剂的醇类选择氧化反应,产物以醛或酮为主,且该催化剂能够多次循环使用而不降低活性．XRD结果表明,负载在Al2O3上的锰主要是以颗粒状β-MnO2形式存在,少量铈的加入能够促进锰的分散,使负载的β-MnO2颗粒变小,从而呈现较高的催化活性．当锰铈原子比为9：1时,催化活性最高．焙烧温度影响催化剂的结构和组成,在较低的温度下（300℃以下）硝酸锰仅能部分分解为β—MnO2,而过高的温度（700℃）将使β-MnO2发生分解,从而降低催化活性．另外,本文还研究了氧分压、反应温度等动力学因素对催化反应性能的影响以及催化剂的稳定性．     

乙烯一步氧化法制乙醛过程的实时优化方法

本文讨论了乙醛生产过程的实时优化,提出了以乙醛的收率作为优化目标,建立优化模型来调整操作参数以提高乙醛收率.优化模型基于2个软测量模型,它们被实时校正以准确反映实时过程状态.实践表明实时优化的有效性,在总体上提高了乙醛收率,带来了可观的经济效益.     

镍基催化剂对乙烷氧化脱氢制乙烯性能的研究

用均匀沉淀法制备了片状复合氧化镍NiMO(M=Li,Sr,Y,Fe,La)催化剂,并研究了其对乙烷氧化脱氢制乙烯的催化性能.采用X射线衍射(XRD)、扫描电子显微镜(SEM)、程序升温还原(H2-TPR)和程序升温脱附(O2-TPD)等方法对镍基催化剂进行了表征.X射线衍射和扫描电子显微镜检测结果表明:助剂的加入对催化剂的形貌影响不大,仍为片状结构;平均粒径为5~10 nm.程序升温还原和脱附表征结果表明:助剂Li,Sr并未进入NiO晶格;而助剂Y,Fe,La与Ni之间具有相互作用,因而影响催化剂的理化性质和催化活性.其中,Fe掺杂的片状氧化镍催化剂对乙烯的选择性和收率均有所改善,340℃时NiFeO催化剂上的乙烯收率可达18.2%.     

乙烷氧化脱氢的研究进展

就近年来乙烷氧化脱氢反应制乙烯的研究进展 ,主要针对以 O2 作氧化剂时所使用的催化剂进行了综述 ,包括不同种类催化剂的反应性能及反应工艺条件、动力学和反应机理 .对以 N2 O和 CO2 作氧化剂也作了相应的介绍     

尾式酪氨酸卟啉及其金属配合物的合成

报道了５－［（对－Ｎ－酪氨酸丁氧基）苯基］－１０,１５,２０－三（对－氯苯基）卟啉（Ｈ２Ｌ）及其配合物ＭＬＣ１（Ｍ＝Ｃｏ,Ｆｅ,Ｍｎ）的合成,经元素分析、ＵＶ－ｃｉｓ、荧光光谱、ＩＲ和＾１ＨＮＭＲ等结构表征。催化实验发现除配体外,３种配合物在分子氧氧化苯甲醛的反应中具有催化作用。     

CuCe-O_x催化剂表面物种对CO催化氧化性能影响

选取不同沉淀剂采用共沉淀法制备了CuCe-Ox复合氧化物催化剂.考察了沉淀剂对其CO催化氧化性能的影响.研究表明以氨水为沉淀剂的催化剂CO氧化活性最佳,它与CuCe-Ox催化剂具有较多的Ce~(3+)以及CuO物种有关.此外,采用氨水作为沉淀剂可促进CuO的生成,这是CO催化氧化的主要活性位点.     

5-(4-对氯苯基)-10,15,20-三苯基卟啉及其配合物的催化性质研究

对金属卟啉催化性质的研究愈来愈引起人们的关注，尤其是与分子氧有关的催化反应〔１〕．该文研究了标题卟啉（Ｈ２Ｐ）及其６种配合物存在下，用分子氧氧化芳醛的催化过程，测定了反应体系的吸氧动力学曲线     

铈部分取代镧的La—Mn系钙钛矿型催化剂性能研究

采用共沉淀法制得了Ｃｅ＾４＋部分取代Ｌａ＾３＋的Ｌａ１０ｘＣｅｘＭｎＯ３钙钛矿型催化剂，结果表明，随Ｃｅ＋＋取代量ｘ的增加，Ｌａ１－ｘＣｅｘＭｎＯ３催化剂越易还原，其还原活化能逐渐降低，对ＣＯ、ＣＨ４氧化反应其活性有一最佳值，对ＣＯ反应ｘ为０．４；对ＣＨ４反应ｘ为０．２，这是由于随ｘ的增大，催化剂晶格缺陷增多，晶格氧的化学势增大而造成的。     

Some Aspects of the Catalytic Organic Synthesis

1 Results Catalytic reactions are gaining importance due to its low cost, operational simplicity, high efficiency and selectivity. It is also getting much attention in green synthesis. Many useful organic reactions, including the acylation of alcohols and aldehydes, carbon-carbon, carbon-nitrogen, carbon-sulfur bond forming and oxidation reactions are carried out by catalyst. We are exploring the catalytic acylation of alcohols and aldehydes in a simple and efficient manner. Catalytic activation of unr...     

甲烷在镁表面上的氧化偶联

XPS和UPS研究结果表明,在金属镁表面氧化过程中存在的过渡态氧O~(δ-)对甲烷有很强的脱氢活性,生成CH_x(x=1,2,3)和深度氧化吸附态CO_3~(2-),以质谱和色谱研究结果表明,CHx偶联生成乙烷和乙烯,CO_3~(2-)热分解生成CO和CO_?。     

复合助剂对VPO催化剂物性的影响

以V2O3、浓H3PO4为原料,浓Hcl和柠檬酸作还原剂,加入一定含量不同金属离子作为助剂采用超临界流体干澡法制备了VPO催化剂,并在不同气氛下进行活化．应用BET、XRD、XPS等表征手段,考察了各VPO催化剂粒子的比表面积、晶相结构及表面V离子价态等物性．实验表明：采用超临界流体干燥法可使催化剂的比表面积显著增加,助剂的种类和量不同,活化气氛不同,对催化剂比表面积的影响也不同,助剂的种类对催化剂的晶相结构也有一定的影响．但对催化剂表面V离子价态影响不大．     

Catalytic Asymmetric Carbon-Carbon Forming Reactions Catalyzed Chiral Schiff Base-Metal Complexes

1 Results In 1991, we disclosed the novel asymmetric catalysts prepared from chiral Schiff base and titanium alkoxide in the reaction of asymmetric silylcyanation of aldehydes (eq.1)[1]. Since our first report, chiral Schiff base-metal complex was proven to be efficient in a variety of asymmetric reactions. We reported the first example of enantioselective addition of diketene to aldehydes promoted by chiral Schiff base-titanium alkoxide complexes (eq.2)[2]. The products of this reaction have been cove...     

In situ time-resolved FTIR investigation on the reaction mechanism of partial oxidation of methane to syngas over supported Rh and Ru catalysts

In situ time-resolved FTIR spectroscopy was used to study the reaction mechanism of partial oxidation of methane (POM) to synthesis gas and the reaction of CH4/O2/He (2/1/45, molar ratio) gas mixture with adsorbed CO species over Rh/SiO2, Ru/γ-Al2O3 and Ru/SiO2 catalysts at 500-600℃. It was found that CO is the primary product of POM reaction over reduced and working state Rh/SiO2 catalysts. Direct oxidation of CH4 is the main pathway of synthesis gas formation over Rh/SiO2 catalyst. CO2 is the primary product of POM over Ru/γ-Al2O3 and Ru/SiO2 catalysts. The dominant reaction pathway for synthesis gas formation over Ru/γ-Al2O3 catalyst is via the reforming reactions of CH4 with CO2 and H2O. For the POM reaction over Rh/SiO2 and Ru/γ-Al2O3 catalysts, consecutive oxidation of surface CO species is an important pathway of CO2 formation.     

CO在Cu-Mn催化剂上催化氧化本征反应动力学研究

本文采用共沉淀法制备了用于低温CO催化氧化的Cu-Mn催化剂,对其进行了XRD分析和SEM表征,结果表明非晶态催化剂在室温下显示出良好的氧化活性。在50～80℃范围内研究了CO在所制备Cu-Mn催化剂床层上的催化氧化本征反应动力学,同时测定了CO在Cu-Mn催化剂上的催化反应等温线。结果表明,CO在Cu-Mn催化剂床层上的本征反应是一个表面反应控制的一级催化反应,反应的活化能是43.0kJ.mol-1。     

硝酸铈铵—溴酸钠对肟的选择性氧化研究

在水溶液中,用硝酸铵－溴酸钠串联氧化体系对肟进行选择性氧化生成相应的醛酮。     

Ni—Cu—ZnO催化剂组分间相互作用的研究

研究了Ｎｉ－Ｃｕ／ＺｎＯ催化丙烷氢解反应并用化学吸附和磁化率测量等技术表征了催化剂。随着催化剂中Ｃｕ含量的增加,Ｈ２化学吸附量与磁化率均显著下降,与以前的研究结果相结合,说明Ｎｉ与Ｃｕ相互作用形成了原子簇而且Ｃｕ富集在表面。同时,Ｎｕ－Ｃｕ间也存在电子效应,即Ｃｕ的ｄ电子向Ｎｉ的ｄ轨道进行了转移。丙烷氢解反应进一步表明,Ｎｉ－Ｃｕ／ＺｕＯ中也存在金属－载体相互作用,Ｎｉ－Ｃｕ金属间相互作用以及Ｎｉ     

Biologically inspired oxidation catalysis

The development of processes for selective hydrocarbon oxidation is a goal that has long been pursued. An additional challenge is to make such processes environmentally friendly, for example by using non-toxic reagents and energy-efficient catalytic methods. Excellent examples are naturally occurring iron- or copper-containing metalloenzymes, and extensive studies have revealed the key chemical principles that underlie their efficacy as catalysts for aerobic oxidations. Important inroads have been made in applying this knowledge to the development of synthetic catalysts that model enzyme function. Such biologically inspired hydrocarbon oxidation catalysts hold great promise for wide-ranging synthetic applications.     

在自制钒催化剂上SO_2氧化反应动力学模型的识别——(一)机理模型方程的推导

SO_2在钒催化剂上的氧化反应机理,至今仍未有定论。为了应用,各作者提出适应不同钒催化剂的动力学模型。数年来,我们用云南硅藻土作载体研制钒催化剂,为对其催化反应特征有所了解,采用Yang—Hougen方法,推导出四个机理模型的13个反应动力学方程,作为与实验数据拟合的竞争模型,以建立所研制的钒催化剂的动力学方程,供工艺条件选择和反应器设计参考,本文仅报道模型方程的推导,后文再报道识别结果,以求系统。