温和条件下环己烯氧化催化体系研究进展

分子氧催化氧化环己烯的关键在于催化剂的制备。本文对均相催化反应体系中金属卟啉、酞菁、席夫碱、吡啶酰胺等仿生催化剂及其在相应非均相催化反应体系中对环己烯催化氧化性能的研究现状进行了分析。提出了分子氧催化氧化环己烯应采用高活性、高选择性的非均相仿生催化剂。     

钴卟啉对空气氧化环己烯合成环己烯酮的催化作用

引　言环己烯酮是一种非常重要的化工中间体 ,广泛应用于医药和农药中 ,如环己烯酮类除草剂[1] .取代后的环己烯酮是合成取代苯酚的中间体[2 ] .环己烯酮较早的合成方法是在冰醋酸溶剂中铬酐氧化环己烯制得[3] .该法产率低、分离困难且污染严重 .为此 ,化学家做了大量的工作 .乙酰丙酮钴[4 ] 、组氨酸席夫碱锰配合物[5] 等被用来催化分子氧氧化环己烯合成环己烯酮 ,环己烯转化率和环己烯酮选择性均取得较好的效果 ,但反应需要较高比例的溶剂 .谢高阳等以钯单取代十二钼磷酸盐催化氧化环己烯[6 ] ,环己烯酮选择性为摩尔比 36 % .金属卟啉在催…     

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.     

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.     

SiO2负载钴系催化剂的环己烯环氧化性能

采用沉积沉淀法制备不同负载量的SiO₂（硅胶）负载钴氧化物催化剂,采用X射线衍射（XRD）、X射线光电子能谱（XPS）、透射电镜（TEM）、N₂吸脱附等手段对催化剂进行表征,结果表明钴系氧化物为Co₃O₄,并且钴氧化物均匀地负载在SiO₂（硅胶）载体上,其活性组分的粒子大小集中分布在2～10nm。将制备的催化剂应用于环己烯环氧化反应,以环己烯、分子氧为原料,异丁醛为催化助剂,N,N-二甲基甲酰胺（DMF）为反应溶剂,在高压釜中进行。同时将SiO₂负载钴氧化物催化剂与不同载体上制备的钴系催化剂进行比较,发现催化剂用量0.20g、环己烯2.00g、异丁醛3.50g、反应温度50℃、反应时间5h、氧气压力4MPa时,环己烯的转化率和环氧环己烷的选择性分别可达到66.56%和71.03%。     

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%。     

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。     

Mn saloph/ZSM-5催化环己烯环氧化性能的研究

采用柔性配体法以ZSM-5型分子筛为载体,固载Schiff碱锰配合物,制备了分子氧环氧化环己烯的催化剂Mn saloph/ZSM-5,并用FT IR、ICP、TG-DTA以及BET等技术对其进行表征。对其催化分子氧环氧化环己烯制备环氧环己烷的工艺条件进行探索,结果表明,在35℃,环己烯2 mL,乙腈20 mL,异丁醛5 mL,催化剂40 mg的条件下,,环氧环己烷的单程收率可达78.73%,且催化剂易于分离回收。     

环己烯催化环氧化合成环氧环己烷反应研究

以双醛淀粉Schiff碱钴配合物为催化剂,分子氧为氧化剂、异丁醛为引发剂,研究了乙腈溶液中环己烯合成环氧环己烷的工艺过程,考察了各种因素对环氧化反应的影响及催化剂重复性能。结果表明,催化剂用量1.2%,氧气流量20 m L/min,醛烯摩尔比2,温度35℃,时间8 h,此时环己烯的转化率和环氧环己烷的选择性可达到82.8%,71.2%;催化剂分离回收容易,可重复使用3次。     

环己烯催化环氧化合成环氧环己烷反应研究

以双醛淀粉Schiff碱钴配合物为催化剂,分子氧为氧化剂、异丁醛为引发剂,研究了乙腈溶液中环己烯合成环氧环己烷的工艺过程,考察了各种因素对环氧化反应的影响及催化剂重复性能。结果表明,催化剂用量1.2%,氧气流量20 m L/min,醛烯摩尔比2,温度35℃,时间8 h,此时环己烯的转化率和环氧环己烷的选择性可达到82.8%,71.2%;催化剂分离回收容易,可重复使用3次。     

Allylic Oxidation of Cyclohexene with Molecular Oxygen Using Cobalt Resinate as Catalyst

Allylic oxidation of cychohexene under atmospheric pressure of molecular oxygen was carried out over cobalt resinate in the absence of solvent. It was shown that cobalt resinate exhibited promising catalytic activity for the oxidation of cyclohexene to 2-cyclohexen-1-ol and 2-cychohexen-1-one under mild condition for the first time.     

锰卟啉-醋酸钴复合催化体系对甲苯氧气氧化的催化作用

研究了在无溶剂体系中,对氯四苯基锰卟啉［T(p-Cl)PPMnCl］和醋酸钴［Co(OAc)2］复合催化下,空气氧化甲苯制苯甲醛、苯甲醇和苯甲酸的新工艺。实验发现,T(p-Cl)PPMnCl/Co(OAc)2为复合催化剂时比单独使用T(p-Cl)PPMnCl 或Co(OAc)2时有更高的甲苯转化率和苯甲醛、苯甲醇、苯甲酸的收率,表现出明显的复合催化作用。研究表明,反应温度、反应时间和催化剂比例对T(p-Cl)PPMnCl/Co(OAc)2的复合催化效果有影响。     

PTA氧化催化剂技术及其应用

PTA氧化生产采用钴锰溴三元复合催化体系,现采用多种复合形态的催化剂。笔者综合比较固态的钴锰醋酸盐、溶液态钴锰溴催化剂及溶液态钴锰溴化物复合催化剂。分析表明这3种形态的催化剂催化性能相当,PTA生产的单位消耗相近;溶液态钴锰溴化物复合催化剂使用方便且制造成本较低。     

Influence of catalyst type on the curing process and network structure of alkyd coatings

Recent studies have shown that cobalt catalysts, used for curing of alkyd coatings, are potentially carcinogenic, and hence replacement by new environmental friendly catalysts is needed. The influence of different metal based catalysts on the oxidation process has been studied extensively in model systems, consisting of unsaturated oils. However, these results may not be representative for real coatings, since in these systems the oxygen diffusion is much lower than in model systems and therefore may have a large effect on the curing. In this paper, we will show how the curing of an alkyd coating depends on the type of catalyst (cobalt or manganese based). The curing process is studied using a high spatial resolution nuclear magnetic resonance (NMR) setup. The final network structure and cross-link density are found to be correlated with the catalyst used, i.e. a cobalt based catalyst and two manganese based catalysts. The difference in final network structure is investigated by NMR T₂ relaxation analysis and the glass transition temperature T_g measured using a differential scanning calorimeter (DSC). In case of the cobalt based catalyst a cross-linking front was observed and a high cross-link density was found, compared to the manganese based catalysts, in which case no sharp cross-linking front was observed. To interpret the observed NMR profiles in more detail, simulations based on a reaction-diffusion model were performed. From the results of these simulations estimates were obtained for the reaction constants and the diffusion of oxygen for the different catalysts.     

环己烯催化环氧化反应的研究新进展

综述了环己烯催化氧化法合成环氧环己烷的最新研究进展。近年来,催化环己烯环氧化越来越受到关注,因为它采用了来源方便和具有环保性质的氧化剂。介绍了环己烯催化环氧化的一些新进展。反应中采用了各种氧化剂如过氧化氢(双氧水),叔丁基过氧化氢(TBHP)和分子氧(O2),以及各种含有各种配体(如席夫碱、卟啉、酞菁和杂多酸)的过渡金属催化剂。对有关反应的机理进行了讨论。     

Catalytic Oxidation of Oleic Acid in Supercritical Carbon Dioxide Media with Molecular Oxygen

Oxidation of oleic acid was performed over various ordered porous catalysts containing transition metal in supercritical carbon dioxide (scCO₂) media with molecular oxygen. Oleic acid was completely decomposed into mono- and dicarboxylic acids over porous catalysts, viz., mesoporous molecular sieves (CrMCM-41, MnMCM-41, CoMCM-41) and microporous molecular sieves (CrAPO-5, CoMFI, MnMFI) using scCO₂ at 353 K for 8 h. Among the different catalysts studied, microporous and mesoporous catalysts containing chromium, in presence of scCO₂ showed high distribution of azelaic and pelargonic acids as compared to their analogs containing cobalt or manganese. The presence of scCO₂ medium with the catalysts increased the distribution of azelaic and pelargonic acids. The effect of CO₂ pressure, reaction temperature and reaction time on oxidation of oleic acid over CrMCM-41 was also investigated. Additionally it is noticed that the catalyst can be recycled with negligible loss of catalytic activity.     

Synthesis and catalytic oxidation properties of polymer‐bound cobalt complexes

Polymer‐bound 2,2′‐bipyridine cobalt complexes PSBPY‐Co, PSBPY‐Co‐bipy, PSBPY‐Co‐oxine, and PSBPY‐Co‐phen (where PSBPY: polystyrene bound‐2,2′‐bipyridine; bipy: 2,2′‐bipyridine; phen: 1,10‐phenanthroline) were synthesized and investigated by IR, X‐ray photoelectric spectroscopy, thermogravimetry–differential thermal analysis, inductively coupled plasma atomic emission spectrometry, and elemental analysis. The complexes were found to be catalysts for the oxidation of alkylbenzenes and cyclohexene in the presence of molecular oxygen in the absence of solvent. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1068–1074, 2000