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。     

以分子氧为氧源催化苯乙烯环氧化催化剂研究进展

环境友好催化烯烃环氧化是催化氧化领域中的一大热点,分子氧作为一种理想的清洁氧源日益受到人们的重视,而分子氧在常温下非常稳定,必须经过适当的催化才能与烯烃发生环氧化反应。本文综述了近年来以分子氧为氧源催化苯乙烯环氧化所用催化剂的主要研究进展,并对其前景进行了展望。     

烃类氧化新的N-羟基邻苯二甲酰亚胺基催化氧化体系

烃类氧化反应是石油化工中一类重要反应。空气和氧气是容易得到且环境友好的氧化剂,所以以氧为氧化剂的具有高选择性和转化率的催化体系的开发在烃类氧化中具有极其重要意义。本文在对传统的烃类分子氧氧化催化剂进行讨论的基础上,对近年来出现的以N-羟基邻苯二甲酰亚胺为基础的新催化剂体系进行了综述。该催化体系催化的烃类分子氧氧化反应具有反应条件温和、选择性高等优点。     

负载型Ce、La催化氧化脱除柴油中有机硫化物

Ce基催化剂因其具有较强的储放氧功能,在催化氧化反应中有着广泛的应用。而其用于催化氧化脱除柴油中有机硫化物的研究,并未有报道。本文用负载法制备Ce、La高丰度稀土元素的催化剂,用于催化分子氧氧化脱除柴油中硫化物,旨在分析其催化氧化效果。结果表明:反应温度越高其催化氧化活性越大,柴油脱硫率最高达70%以上。     

节能降耗、环境友好的催化氧化研究新进展

从饱和烃功能化 ,分子氧活化 ,氧化还原分子筛 ,仿酶催化剂等方面评述了催化氧化新进展     

多相催化剂用于高级烯烃分子氧选择性氧化的研究进展

针对以高级烯烃作为底物进行的分子氧氧化反应,所用多相催化剂按其结构和组成不同,可分为金属-有机配体复合催化剂、金属氧化物催化剂、无机分子筛催化剂、多氧金属盐类催化剂和负载型催化剂等。综述了各类催化剂用于高级烯烃分子氧选择性氧化的研究进展,并比较了各自的优缺点,指出负载型催化剂在一定程度上克服了其他几类催化剂存在的催化氧化选择性差、重复利用率低、稳定性差等缺点,有望在无溶剂的条件下获得较佳的转化率及选择性,是未来高级烯烃绿色氧化催化剂的重要研究方向。     

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。     

贵金属液相非均相催化氧化甘油制备二羟基丙酮的研究进展

阐述了化学法中以分子氧为氧化剂,负载型贵金属催化剂液相非均相催化氧化甘油制备二羟基丙酮(DHA)过程的研究进展。叙述了多种贵金属催化剂催化氧化甘油制备DHA的效果及其反应过程中的影响因素。最后对负载型贵金属液相非均相催化氧化甘油制备DHA的研究过程进行展望。     

贵金属液相非均相催化氧化甘油制备二羟基丙酮的研究进展

阐述了化学法中以分子氧为氧化剂,负载型贵金属催化剂液相非均相催化氧化甘油制备二羟基丙酮(DHA)过程的研究进展。叙述了多种贵金属催化剂催化氧化甘油制备DHA的效果及其反应过程中的影响因素。最后对负载型贵金属液相非均相催化氧化甘油制备DHA的研究过程进行展望。     

催化分子氧氧化醇类的研究进展

综述了用氧气或空气（分子氧）作为化学计量氧化剂,在催化剂作用下氧化醇类的研究进展,并对某些代表性的催化氧化反应的特点和选择性进行了讨论。     

Low-Temperature Ammonia Oxidation Over Pt/γ-Alumina: The Influence of the Alumina Support

Deactivation of a Pt/-alumina catalyst used for low-temperature ammonia oxidation was studied using positron-emission profiling (PEP). Evidence is presented that irreversibly adsorbed nitrogen and oxygen species deactivate the catalyst. This deactivation is further accelerated by preadsorption of oxygen on the catalyst. Ammonia strongly interacts with the alumina support. A steady state of the ammonia oxidation reaction is reached after the alumina sites are saturated with ammonia. PEP experiments show that spillover of oxygen to the support is not significant during the ammonia oxidation.     

以分子氧为氧化剂合成柠檬醛的研究

分子氧(或空气)是化工生产中的“绿色”氧化剂。用分子氧催化氧化醇类以合成不同的羰基化合物的研究已成为近几年来国外有机合成的一个热门研究领域。综述了以分子氧合成柠檬醛的研究。使用的Ru／Al2O3催化剂对醇-OH基的氧化具有高度的选择性并有很高的转化率。     

醇类的分子氧催化氧化反应研究进展

目前,国外广泛地使用分子氧(或空气)催化氧化醇类以合成羰基化合物。分子氧是化工生产中很受欢迎的一种“绿色”氧化剂而且便宜易得。此处介绍的是目前国外已发现的多种这类反应的以铂系金属为主的催化剂。它们大多数具有高的催化转化率和很好的选择性。     

Effect of pyrolysis temperature of the catalytic activity of active carbon+cobalt phthalocyanine in sulfur dioxide oxidation by oxygen

Structural changes during the pyrolysis of the catalyst active carbon+cobalt phthalocyanine (Ac+CoPc) in the temperature range 500–800°C are investigated using infrared spectroscopy, XRD and DTG analysis. The decomposition products contain organic residues of the phthalocyanine rings and separate phases of CO3O4 and -Co. The effect of pyrolysis temperature on: (i) the chemical stability of Co in the pyrolyzed CoPc in 0.5M H2 SO4; (ii) the electrocatalytic activity for oxidation of SO2 by oxygen; and (iii) the partial electrochemical reactions of SO2 oxidation and oxygen reduction, has been studied. The rate of electrochemical oxidation of SO2 is affected only by the active centres formed on pyrolysis of the chelate rings. The presence of Co at lower pyrolysis temperatures decreases the oxygen diffusion limitations. It is shown that the rate of SO2 oxidation by oxygen is limited by mass transport of oxygen.     

用分子氧催化氧化法制取苯甲醛的研究简介

用分子氧催化氧化醇类以合成不同的羰基化合物的研究已成为近几年来国外在工业过程和有机合成中的一个热门研究领域。分子氧(或空气)是化工生产中的"绿色"氧化剂。使用的催化剂对醇羟基的氧化具有高度的选择性并有很高的转化率。简要介绍以此类方法对合成苯甲醛的研究。     

烟酸制备的研究进展

文章介绍了烟酸的各种合成工艺方法,包括当前工业上生产烟酸常用的氨氧化法和硝酸氧化法。其中主要介绍了对环境友好的用氧气作为氧化剂催化氧化制备烟酸的方法和电化学合成方法。对生物转化法和臭氧氧化法的最新研究成果也作了描述。寻找新型催化剂催化氧气或空气氧化3-MP、MEP制备烟酸,开发无污染的烟酸生产工艺,是绿色化学化工发展的必然要求,具有重要的意义。     

Effects of Oxygen Transfer Limitation and Kinetic Control on Biomimetic Catalytic Oxidation of Toluene

Under oxygen transfer limitation and kinetic control, liquid-phase catalytic oxidation of toluene over metalloporphyrin was studied. An improved technique of measuring dissolved oxygen levels for gas-liquid reaction at the elevated temperature and pressure was used to take the sequential data in the oxidation of toluene catalyzed by metalloporphyrin. By this technique the corresponding control step of toluene oxidation could be obtained by varying reaction conditions. When the partial pressure of oxygen in the feed is lower than or equal to 0.070 MPa at 463 K, the oxidation of toluene would be controlled by oxygen transfer, otherwise the reaction would be controlled by kinetics. The effects of both oxygen transfer and kinetic control on the toluene conversion and the selectivity of benzaldehyde and benzyl alcohol in biomimetic catalytic oxidation of toluene were systematically investigated. Three conclusions have been made from the experimental results. Firstly, under the oxygen transfer limitation the toluene conversion is lower than that under kinetic control at the same oxidation conditions. Secondly, under the oxygen transfer limitation the total selectivity of benzaldehyde and benzyl alcohol is lower than that under kinetic control with the same conversion of toluene. Finally, under the kinetics control the oxidation rate of toluene is zero-order with respect to oxygen. The experimental results are identical with the biomimetic catalytic mechanism of toluene oxidation over metalloporphyrins.     

Reduction and oxidation kinetics of Mn3O4/Mg-ZrO2 oxygen carrier particles for chemical-looping combustion

The kinetics of reduction with methane and oxidation with oxygen of Mn₃O₄ supported on Mg-ZrO₂ prepared by freeze granulation has been investigated. The reactivity experiments were performed in a thermogravimetric analyzer (TGA) using different reacting gas concentrations and temperatures in the range of 1073-1223 K. The oxygen carrier particles showed high reactivity during both reduction and oxidation at all investigated temperatures. An empirical reaction model, which assumes a linear relation between time and conversion, was used to determine the kinetic parameters for reduction and oxidation, with chemical reaction being the main resistance to the reaction. The order of reaction found was 1 with respect to CH₄ and 0.65 with respect to O₂. The activation energy for the reduction reaction was 119 and for the oxidation reaction. The reactivity data and kinetic parameters were used to estimate the solid inventory in the air and fuel reactor of a CLC system. The optimum solid inventory obtained was at a value of ΔX_s=0.4. At these conditions, the recirculation rate of oxygen carrier between air and fuel reactor was per MW of fuel, which could be accomplished in an industrial reactor. The high reactivity of the Mn₃O₄/Mg-ZrO₂ with both methane and oxygen showed that this is a very promising oxygen carrier for CLC.     

Strategies for oxidation catalyzed by polyoxometalates at the interface of homogeneous and heterogeneous catalysis

A basic premise behind the use of polyoxometalates in oxidation chemistry is the fact that polyoxometalates are oxidatively stable. This, a priori, leads to the conclusion that for practical purposes polyoxometalates would have distinct advantages over widely investigated organometallic compounds that are vulnerable to decomposition due to oxidation of the ligand bound to the metal center. Since polyoxometalate synthesis is normally carried out in water by mixing the stoichiometrically required amounts of monomeric metal salts and adjusting the pH to a specific acidic value many structure types are accessible by variation of the reaction stoichiometry, replacement of one or more addenda atoms with other transition or main group metals, and pH control. The structural variety available has enabled the use of polyoxometalates as catalysts for oxidation of hydrocarbons and functionalized organic substrates (alcohols, amines, sulfides, etc.) with a wide range of oxygen donors ranging from molecular oxygen, hydrogen peroxide, nitrous oxide, ozone, alkyl hydroperoxides, periodate, sulfoxide and others. The wide purview of oxidation reactions is enabled because the structural variety leads to oxidation through a number of different mechanistic motifs.From a synthetic organic point of view, the most applicable uses of polyoxometalates as catalysts involve the green oxygen donors – hydrogen peroxide and molecular oxygen. Since practical applications are in hand in this area, practical considerations concerned with catalyst recycle and/or recovery and the elimination of environmentally problematic solvents are also coming to the forefront. In this paper, we will present some of our activities in the area of catalyst engineering for catalytic synthetic applications by polyoxometalates including: (a) catalytic mesoporous solids from organic-polyoxometalate hybrid materials, (b) fluorous phase polyoxometalates with and without fluorous solvents and (c) the use of aqueous biphasic media for oxidation with hydrogen peroxide.