环己烷分子氧氧化多相催化剂研究进展

综述了环己烷分子氧氧化多相催化剂最新研究进展;重点介绍了金系催化剂和钴系催化剂;指出环己烷分子氧氧化制环己酮和环己醇工艺存在选择性和转化率低、能耗高等缺点,解决问题的主要途径在于开发高效催化剂.金系催化剂在环己烷分子氧氧化中具有较好的应用前景.     

分子氧氧化环己烷制环己酮催化剂的研究进展

综述了分子氧氧化环己烷制取环己酮的催化剂的研究进展,重点介绍了光催化剂、纳米催化剂、仿生催化剂、分子筛催化剂和复合催化剂在环己烷催化氧化方面的应用,其中,负载在分子筛上的纳米金催化剂具有较高的催化活性、选择性及稳定性。     

分子氧一步法氧化环己烷合成己二酸技术进展

传统的环己烷两步法生产己二酸工艺过程复杂,反应条件苟刻,能量消耗较高,且产生大量有害的NOx气体,污染环境。而以分子氧为氧化剂、环己烷为原料一步法直接合成己二酸具有工艺流程短、氧化剂廉价易得、工艺绿色环保等优点,被誉为是最有希望实现己二酸绿色生产的技术之一。根据催化体系的不同从均相催化和多相催化两个维度概述分子氧一步法氧化环己烷合成己二酸的技术进展,内容涵盖可溶性金属催化法、有机小分子催化法、分子筛催化法以及负载金属催化法等,并对各合成方法的优缺点进行对比说明。     

环己烷分子氧选择性氧化固体催化剂研究进展

对环己烷分子氧催化氧化制环己酮固体催化剂的最新进展进行了综述,重点介绍了贵金属催化剂、过渡金属及其氧化物催化剂和分子筛催化剂。指出锆基复合氧化物催化剂和负载在分子筛上的金催化剂具有较高的催化活性和选择性及好的稳定性,具有一定的应用及工业化前景。     

金属席夫碱催化分子氧氧化环己烷的研究

采用两步法合成了两类共18种金属席夫碱配合物,将其用于催化环己烷的氧化反应。结果表明:金属席夫碱配合物在温和条件下能有效催化环己烷的反应,生成目的产物;双核金属席夫碱催化效果较单核好。     

环己烷富氧氧化制环己酮的研究

研究了环己烷富氧氧化的特征,考察了进气氧浓度的提高对反应速度、选择性、安全性和经济性的影响。通过工业化试验,控制氧气体积分数30%,反应温度160～175℃,压力1.0～1.2MPa,环己烷氧化转化率为3%～4%,能很好实现富氧氧化反应,氧化尾气的氧气体积分数可以安全控制在2%～3%。环己烷富氧氧化可用于环己酮装置的改扩建,较空气氧化经济性好。     

环己烷氧化技术的研究进展

综述了环已烷的氧化工艺现状.环己烷氯化催化剂和氧化介质的技术进展情况,开发廉价、高效、清洁的催化荆成为未来的发展趋势.     

负载型纳米催化剂选择性催化氧化环己烷制1,2-环氧环己烷研究

综述了1,2-环氧环己烷工业用途以及常见的工业合成方法,论述了利用环己烷催化合成1,2-环氧环己烷可行性和优点,并展望了利用分子氧选择性催化氧化环己烷制环氧环己烷的工业开发前景.     

环己烷热,冷法贫氧氧化的比较

比较热循环法与冷循环法泊工艺控制指标、贫氧空气中组分、运行参数、热平衡参数、循环压缩机选用参数、按折标煤能耗，认为冷循环法贫氧氧化较热循环法优越性明显，是环己烷催化贫氧氧化的发展方向。     

分子氧/乙醛/过渡金属盐体系氧化环己烯的研究

采用分子氧／乙醛／过渡金属盐催化剂体系氧化环己烯合成环氧环己烷,此方法与传统的有机过氧化物氧化的方法相比,具有安全、简便、高效的特点。通过对影响此反应的过渡金属盐催化剂种类、用量以及反应物配比等主要因素的考察,可使氧化反应产物1,2-环氧环己烷的收率最高可达78．2％。     

Nanoscale Cu supported catalysts in the partial oxidation of cyclohexane with molecular oxygen

Cu supported catalysts (support: γ-Al₂O₃, Fe₂O₃, TiO₂) have been conveniently prepared by deposition of Cu particles from acetone solvated Cu atoms. The catalysts have been characterized by HRTEM analysis, showing a quite homogeneous Cu particle size distribution. They are active systems for the partial oxidation of cyclohexane to cyclohexanol and cyclohexanone. After the catalytic experiment the Cu/γ-Al₂O₃ and Cu/TiO₂ systems can be reused without valuable loss of activity, while the Cu/Fe₂O₃ system is quite inactive.     

仿生催化氧气氧化环己烷合成已二酸反应条件的研究

以环己烷为原料,氧气为氧化剂,仿生催化剂邻氯铁卟啉为催化剂,一步合成己二酸.考察了反应温度、反应时间、氧气压力、催化剂用量等因素对反应的影响,发现上述因素均对己二酸收率有显著影响,且都有一个最佳的值.催化剂邻氯铁卟啉在该反应中有良好的催化活性,且活性转化数很高.优选的反应条件是反应温度为140℃,氧气压力为2 5 MPa,反应时间为8 h,催化剂用量为1.5 mg.在此条件下,己二酸的质量收率可达21.4%,活性转化数可达24 582.     

Photocatalytic oxidation of cyclohexane over TiO2 nanoparticles by molecular oxygen under mild conditions

The structure, physical characteristics and photocatalytic selective oxidation properties of nanometer‐size TiO₂ particles produced by a sol–gel method were studied by X‐ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), X‐ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR) and photocatalytic selective oxidation measurements. Analysis of the XRD results shows that sol–gel‐produced TiO₂ nanoparticles have the anatase structure at annealing temperatures ≤973 K, that the rutile structure begins to emerge at annealing temperatures ≥973 K and the particles have the pure rutile structure at 1023 K. DRS indicates that the obtained TiO₂ nanoparticles exhibit a blue shift with decreasing crystallite size. Analysis of the XPS results shows that the TiO₂ nanoparticles have a lot of oxygen vacancies. The EPR spectrum of TiO₂ at 77 K is composed of a strong isotropic EPR Surface‐Ti³⁺ signal(I) at g = 1.926 and a weak broad Bulk‐Ti³⁺ signal (II) at g = 1.987. Quantitative EPR indicates that both signals show a size and temperature dependence. Photocatalytic oxidation of cyclohexane into cyclohexanol with high selectivity and activity has been obtained by activation of molecular oxygen over sol–gel‐produced TiO₂ nanoparticles under mild conditions in dry solvent, which reveals that the quantum size effect and surface state effect of nanoparticles are key points for governing the selective photocatalytic reaction. The photocatalytic oxidation mechanism under dry solvent is different from that in aqueous solutions. Copyright © 2003 Society of Chemical Industry     

A highly active Au/Al2O3 catalyst for cyclohexane oxidation using molecular oxygen

The selective oxidation of cyclohexane to cyclohexanone and cyclohexanol has been investigated over Au/Al₂O₃ catalysts using molecular oxygen in a solvent-free system. The catalysts were prepared by a modified direct anionic exchange method and characterized by AAS, N₂ adsorption and TEM. The results showed that the catalytic performance of Au/Al₂O₃ is very high in terms of turnover frequency. Moreover, the nano-size effect of gold is also reported in the reaction.     

Synthesis of heterogeneous copper complex catalyst for oxidation of cyclohexane using molecular oxygen

Binuclear macrocyclic copper complex was synthesized and bonded ionically to the montmorillonite clay to enhance thermal stability upto 600°C. The oxidation of cyclohexane using molecular oxygen in the absence of initiators, promoters and coreactants has been studied in the temperature range 145–190°C. The overall cyclohexane conversion was 21% at 180°C and cyclohexanone, the major product with 71% selectivity. The experimental data were analyzed against kinetic scheme proposed and the rate constants determined using Genetic Algorithm.     

One-step oxidation of cyclohexane to adipic acid

Liquid-phase oxidation of cyclohexane with Co(III) catalyst and gaseous oxygen was found to be influenced by reaction temperature, catalyst concentration and the duration. Maximum adipic acid product selectivity (77%) with about 85% cyclohexane conversion was attained at 100°C using catalyst: cyclohexane molar ratio 0·08. Under these conditions more than 80% cyclohexane was converted in the first hour, although selectivity to adipic acid continued to increase for the next 5 h. Cyclohexyl acetate and cyclohexyl monoadipate were identified as important intermediates. This study supports the mechanism proposed by Schultz, J. G. D. and Opchenko, A., J. Org. Chem., 38 (21) (1973) 3729.