Selective Allylic oxidation of Cyclohexene by a Magnetically Recoverable Cobalt Oxide Catalyst

Abstract  

In this work, we prepared a new magnetically recoverable CoO catalyst through the deposition of the catalytic active metal nanoparticles of 2–3 nm on silica-coated magnetite nanoparticles to facilitate the solid separation from liquid media. The catalyst was fully characterized and presented interesting properties in the oxidation of cyclohexene, as for example, selectivity to the allylic oxidation product. It was also observed that CoO is the most active species when compared to Co²⁺, Co₃O₄ and Fe₃O₄ in the catalytic conditions studied.     

分子氧氧化环己烯制备环己烯酮

针对分子氧氧化环己烯制备环己烯酮的催化反应体系,以Co(Ⅱ)为活性中心,3,5-二氯水杨醛与邻苯二胺为配体,胺化的MCM-41型介孔分子筛为载体,用化学键联法制备出一种固载型希夫碱催化剂。进而考察了该催化剂对分子氧氧化环己烯制备环己烯酮的工艺条件,结果表明,在常压、催化剂用量0.15 g(2 mL环己烯)、乙腈20 mL、氧气流量5 mL/min、反应温度60℃、反应时间8 h、叔丁基过氧化氢(TBHP)0.04 mL的条件下,环己烯酮的单程收率达54.87%,催化剂容易分离回收,可重复使用。     

谷氨酸希夫碱钴配合物对环己烯的催化氧化性能研究

研究了谷氨酸水杨醛希夫碱配合物(Sal—Glu—M)对环己烯的催化氧化性能,详细探讨了谷氨酸水杨醛希夫碱钴配合物(Sal—Glu—Co)在不同反应条件下对环己烯的催化氧化性能,找到了谷氨酸水杨醛希夫碱钴配合物对环己烯较好的催化氧化反应条件。     

Vapour Phase Oxidation of Cumene by Molecular Oxygen over MCM-41 Supported Cobalt Oxide Catalyst

Si-MCM-41 and Al-MCM-41 supported cobalt oxide catalysts were prepared and characterized by XRD. The surface area, pore size and wall thickness was calculated by applying BET equation and BJH method using nitrogen sorption technique. DR UV-VIS confirm the presence of cobalt oxide as isolated particle in the framework positions of the MCM-41 mesostructure. The vapour phase oxidation of isopropyl benzene with CO₂-free air as the oxidant was studied over cobalt oxide supported unwashed and washed Si-MCM-41 and Al-MCM-41 catalyst. Isopropyl benzene conversion increased with increase in temperature from 200 to 300 °C, but at 325 °C it decreased. Formation of coke was noted at all the temperatures. Cumenehydroperoxide, 1,2-epoxyisopropylbenzene, acetophenone and styrene were the products observed in this reaction. Of the products cumenehydroperoxide was found to be more selective over all the catalysts. Both unwashed and washed catalysts were found to have nearly the same activity. Due to more dispersion, the active sites in the latter catalysts compensates its low cobalt oxide content in producing activity equal to the former catalysts. The study of time on stream indicated decrease in conversion due to coke formation.     

分子氧氧化环己烯负载型催化剂的制备与选择

在乙醇溶剂中,合成出三种希夫碱配体和四种不同金属离子希夫碱配合物,并用红外线对其结构进行表征,表明合成出希夫碱配体及其配合物.接着以分子氧为氧源,金属希夫碱配合物为催化剂,考察其对环己烯的催化氧化性能,从而筛选出较佳的配位体:水杨醛缩乙二胺配位体和较佳的金属离子钴离子;进而以水杨醛缩乙二胺钴配合物为均相催化剂,采用两种方法将其负载在硅藻土、活性炭、分子筛和石英砂上,并考察该非均相催化剂催化活化分子氧氧化环己烯的催化氧化性能,结果表明,硅藻土为较佳无机载体,固载时,柔性配体法优于浸渍法.     

锰分子筛负载的纳米金催化剂上环己烯氧化研究

用高锰酸钾和硫酸锰在酸性条件下合成的八面体锰分子筛载体(OMS-2)为载体,采用沉积沉淀、浸渍还原、原位合成三种方法制备了OMS-2负载的纳米金催化剂,并进行了X射线衍射(XRD)和透射电镜(TEM)表征。以分子氧为氧化剂,考察了不同反应条件下纳米金催化剂在无溶剂体系中环己烯液相氧化的催化性能。结果表明,沉积沉淀法制备的纳米金催化剂显示出较佳的催化活性,该催化剂在80℃、0.5 MPa、24 h反应条件下,环己烯氧化转化率为39.9%,环己烯醇和环己烯酮的选择性分别为35.5%和51.9%。     

高分子担载谷氨酸希夫碱铜配合物催化氧化环己烯研究

研究了高分子担载水杨醛谷氨酸希夫碱配合物（PS-Sal-Glu-M）催化氧化环己烯的性能,详细探讨了反应温度、反应时间、催化剂用量、反应添加剂对高分子担载水杨醛谷氨酸希夫碱铜配合物催化氧化环已烯的反应性能的影响。研究表明,在常压下,用分子氧作作为氧化剂,不需要溶剂及共还原剂,环己烯可以被氧化生成环己烯醇和环已烯酮,产物的分离提纯比较容易,催化剂可以循环使用。     

超声相转移催化氧化环己烯制备己二酸

以高锰酸钾为氧化剂,使用超声相转移方法氧化环己烯制备己二酸。探讨了反应温度、超声、相转移剂加入量等因素对反应的影响。确定了最佳反应工艺条件为:反应温度为40℃,十六烷基三甲基溴化铵加入量为2%,超声功率为80W,反应4h,己二酸的收率可达41.1%,比未使用超声波方法提高2.1倍。     

固定化光催化氧化技术研究进展

简要介绍了光催化氧化技术的机理、提高催化剂效率的途径、影响反应速率的因素以及反应器的结构形式,最后讨论了该技术的应用前景和发展方向。     

晶格氧用于轻烃的选择氧化

In this paper, selective oxidation of n-butane to maleic anhydride (MA) and partial oxidation of methane to synthesis gas with lattice oxygen instead of molecular oxygen are investigated. For the oxidation of butane to MA in the absence of molecular oxygen, the Ce-Fe promoted VPO catalyst has more available lattice oxygen and provides higher conversion and selectivity than that of the unpromoted one. It is supposed that the introduction of Ce-Fe complex oxides improves redox performance of VPO catalyst and increases the activity of lattice oxygen.For partial oxidation of methane to synthesis gas over LaFeO3 and Lao.8Sro.gFeO3 oxides, the reaction with flow switched between 11% O2-Ar and 11% CH4-He at 900℃ was carried out. The results show that methane can be oxidized to CO and H2 with selectivity over 93% by the lattice oxygen of the catalyst in an appropriate reaction condition, while the lost lattice oxygen can be supplemented by air re-oxidation. It is viable for the lattice oxygen of the LaFeO3 and La0.8Sr0.2FeO3 catalyst instead of molecular oxygen to react with methane to synthesis gas in the redox mode.     

介孔分子筛催化环己烯环氧化研究进展

综述了国内外对介孔分子筛催化环氧化环己烯的研究进展,主要包括金属离子掺杂、有机分子修饰、固载金属氧化物和金属络合物等方面.     

酞菁锰仿生催化去甲肾上腺素氧化的研究

采用UV/Vis法,以酞菁锰（MnPc）为催化剂仿生催化去甲肾上腺素（NA）氧化,系统地研究了催化时间、温度、pH和催化剂用量对催化效率的影响,实验结果表明,MnPc能有效地催化NA氧化生成去甲肾上腺素红。     

催化分子氧环氧化环己烯的研究进展

介绍了分子氧的构型、催化烯烃环氧化机理及其催化环氧化环己烯的研究进展,提出以分子氧为氧源,催化环氧化环己烯的关键在于高效催化剂的制备及廉价易得还原剂的筛选。     

Kinetics of Photocatalyzed Gas Reactions Using Titanium Dioxide as the Catalyst Part II: Photocatalyzed Total Oxidation of Alkanes with Oxygen

In order to obtain a useful expression for the kinetics of the photocatalyzed total oxidation reaction of alkanes with oxygen and TiO₂ as the catalyst, the dependence of the reaction rate on the concentration of the starting material species, the absorbed irradiation intensity, the wavelength of the light and the temperature was investigated. The experiments were performed in a CSTR system. The rate law found for alkane oxidation differs from that obtained for olefin oxidation due to a different reaction mechanism. While a reversible catalyst deactivation process takes place in the latter case, there is no hint of such a process during alkane oxidation. The kinetic data lead to the conclusion that the formation of an alkane and a hydrogen‐radical at a defect site of the catalyst is the first step in the total oxidation reaction of these species followed by the formation of a stronger adsorbed hydroperoxide species. The subsequent transformation of the hydroperoxide into further oxidized species mediated by the electron‐hole pairs generated by the absorbed light on the semiconductor's surface was recognized to be the rate determining step. The reaction behavior for the investigated alkanes could be modeled using this concept with the exception of methane. Its rate law differs strongly from that found for ethane, propane as well as iso‐butane.     

Liquid-Phase Hydrogenation of Benzene to Cyclohexene Using Ruthenium-Based Heterogeneous Catalyst

Selective hydrogenation of benzene to cyclohexene has been studied in a high pressure slurry reactor using supported ruthenium catalysts. The organic base monoethanolamine (MEA) was found to give better selectivities than the conventional inorganic salt additive (zinc sulphate). Parameters studied were the effects of various supports such as alumina, silica, titania, zirconia, niobium oxide, etc., benzene to water ratio, catalyst weight, and presence of cyclohexane in the feed. Reusability of the catalyst was also studied. © 1997 SCI.     

烃类晶格氧选择氧化制顺酐的强制周期操作反应技术

综述了烃类选择氧化制顺酐的生产工艺、反应技术。重点介绍了人为非定态催化反应技术的特点及在烃类晶格氧选择氧化反应中的应用 ,并对烃类选择氧化制顺酐反应提出了今后研究的方向。     

Ruthenium-Catalyzed Aerobic Oxidation of Alcohols on Zeolite-Encapsulated Cobalt Salophen Catalyst

A zeolite-encapsulated cobalt salophen catalyst was prepared by the intrazeolite ligand synthesis method. This catalyst proved to be active in the ruthenium-catalyzed oxidation of primary and secondary alcohols to aldehydes or ketones. Several advantages of the heterogenized catalyst was found in this system compared to the homogeneous counterpart, namely easy handling and better performance (less sensitive to solvent effects, higher specific rates).     

以硫酸铜为催化剂快速测定化学耗氧量

以CuSO4代替Ag2SO4作催化剂,对模拟废水及实际废水进行COD测定。分别考察了CuSO4的用量、H2SO4的用量、消解时间等因素对COD测定结果的影响。结果表明,水样5 mL、浓度为55 g/L的CuSO4溶液投加量为1 mL、H2SO4用量5 mL、消解液用量5 mL、消解时间为8 min时,获得了与国家标准法相近的测定结果。说明该方法测定结果准确、可靠,可以用作废水COD的测定,采用廉价的CuSO4代替昂贵的Ag2SO4作催化剂能大大降低分析成本。