NHPI/Co(Salen)复合催化液相氧化甲苯的工艺考察

为了开发甲苯液相氧化的新催化体系,寻求合适的反应条件提高甲苯选择性氧化生成苯甲醛、苯甲醇的选择性。以分子氧为氧源,在无溶剂条件下,采用N-羟基邻苯二甲酰亚胺(NHPI)与双水杨醛缩乙二胺合钴配合物(Co(Salen))复合催化甲苯液相氧化反应。详细考察了NHPI单独催化以及NHPI与Co(Salen)复合催化过程中NHPI用量、Co(Salen)用量、反应温度、反应时间和氧压对甲苯选择性氧化反应的影响。结果表明:在甲苯0.22 mol,NHPI的摩尔分数2%,Co(Salen)的摩尔分数0.02%,氧压1.60 MPa,110℃的条件下反应2 h,甲苯转化率达到13.6%,苯甲醛选择性32.7%,苯甲醇选择性10.8%,苯甲醛、醇、酸总选择性达97.7%,该反应条件为较佳的工艺条件。     

V-MCM-41介孔分子筛的合成与催化性能

采用三乙醇胺络合物法制备了骨架中含钒量较高的V—MCM-41分子筛催化剂,利用X射线衍射（XRD）和紫外漫反射光谱（UV—vis DRS）等技术对催化剂进行了表征,并考察了硅钒比、反应温度、体积空速、空气与甲苯比对V-MCM-41分子筛在甲苯气相选择性氧化制苯甲醛反应中催化性能的影响。结果表明,骨架中的钒是甲苯选择性氧化生成苯甲醛的活性中心,钒进入骨架中的量与硅钒物质的量比有关,当硅钒比为30时,进入骨架的钒最多,且在甲苯选择性氧化反应中对苯甲醛选择性最高。以硅钒比为30的V-MCM-41分子筛为催化剂,常压下甲苯氧化制苯甲醛较合适的反应工艺为体积空速800h^-1,空气与甲苯物质的量之比5,反应温度450℃。在此条件下,甲苯转化率为20．8％,苯甲醛选择性为41．8％,苯甲醛收率为8．7％。     

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。     

甲苯液相均相选择性催化氧化研究进展

将甲苯液相均相选择性催化氧化反应的催化剂分为：过渡金属盐、杂多化合物、过渡金属配合物、非金属化合物、复合催化剂等,对反应条件、结果和机理进行了总结。杂多化合物或金属卟啉参与反应时,反应条件较温和,对苯甲醛和苯甲醇的选择性高。复合催化剂通常表现出更好的催化性能,而且,当催化剂由非金属催化剂和金属催化剂组成时,对产物的选择性主要取决于金属催化剂部分。此外,以甲苯侧链的氧化为重点阐述了反应机理,指出开发更高效的复合催化剂和粗甲苯的氧化工艺是今后的发展重要方向。     

基于NaClO构建无催化氧化苯甲醇合成苯甲醛的研究

采用NaClO作为氧化剂,不需要加入任何催化剂,构建无催化氧化体系应用于氧化苯甲醇合成苯甲醛,在苯甲醇选择性氧化反应体系中,且在常压条件下,反应时间为24h,考察了不同因素对反应收率的影响,如反应溶剂、反应温度、氧化剂投加量对反应收率的影响,优化的反应条件为：乙酸乙酯为反应溶剂,反应温度为45℃,氧化剂的投加量为300 mL,得到苯甲醛收率为9.3%。然后对无催化氧化体系进行普适性研究,以对硝基苯甲醇、对甲氧基苯甲醇、二苯甲醇以及9-芴醇作为反应物,在优化反应条件下,以5.5%～9.8%收率得到相应产物。因此,基于NaClO的无催化氧化体系为醇氧化合成醛酮开辟了一种反应条件温和、无催化、工艺简单新途径。     

无定型MnO2的制备及其催化苯甲醇选择氧化性能

用KMnO₄和MnSO₄为原料，通过简单的氧化还原过程合成了无定形MnO₂，并用于催化苯甲醇氧化制苯甲醛，发现制得的无定形MnO₂在催化苯甲醇氧化制苯甲醛中表现出较高的活性和苯甲醛选择性（100%）。考察了反应温度、氧浓度、催化剂用量以及反应时间对苯甲醇氧化的影响。结果表明，较高的反应温度和氧浓度以及合适的催化剂用量有利于无定形MnO₂催化苯甲醇氧化生成苯甲醛，在反应温度110 ℃、常压和通氧条件下反应3 h, 苯甲醇转化率和苯甲醛选择性均为100%。     

一种低温气相选择性催化氧化苯甲醇制备苯甲醛的方法

正一种低温气相选择性催化氧化苯甲醇制备苯甲醛的方法,它涉及在低温条件下气相选择性催化氧化苯甲醇制备苯甲醛的方法。本发明是要解决现有的苯甲醇气相氧化生成苯甲醛的反应中,存在反应温度高、催化剂活性差、选择性低和温度耐受范围过窄的问题。方法:常压下,使用固体催化剂Ag/SBA-15,底     

杂多酸催化下苯甲醇氧化合成苯甲醛反应研究

以30％双氧水为氧化剂，以杂多酸为催化剂，对苯甲醇氧化合成苯甲醛反应进行了研究，讨论了各因素对反应的影响，结果表明，杂多酸作为催化剂有较好的催化活性，使用不同的杂多酸催化剂时，随着酸性的增强（磷钨酸＞磷钼酸＞硅钨酸），反应物的转化率和目标产物的选择性都逐渐提高，在相同的条件下，磷钨酸的效果最好，0．6g磷钨酸就可催化100mmol苯甲醇，使其转化率达到92．3％，苯甲醛的选择性为90．3％。     

铜修饰的石墨氮化碳材料催化甲苯液相氧化反应

采用浸渍-焙烧法制备了铜修饰的石墨氮化碳材料Cu-C_3N_4。用XRD、BET、FT-IR及ICP等手段对催化剂的结构及组成进行了表征。考察了以H_2O_2为氧化剂,Cu-C_3N_4对甲苯氧化反应的催化性能,研究了反应条件对催化甲苯氧化反应的影响。在优化的条件下,甲苯转化率达到18.3%,苯甲醇、苯甲醛及苯甲酸的总选择性达到79.4%。     

金属卟啉在催化氧化邻硝基甲苯制取邻硝基苯甲醛反应中定量结构与选择性关系

设计、合成了49个不同结构的金属卟啉催化剂,使用密度泛函方法计算了其几何结构、电荷分布、前线轨道等9种量子化学参数。同时以金属卟啉催化氧气液相氧化邻硝基甲苯制取邻硝基苯甲醛为模型反应,研究了不同结构的金属卟啉对邻硝基苯甲醛选择性的影响。将两者组合,通过逐步回归分析方法找到了影响邻硝基苯甲醛选择性的主要因素,并建立了定量金属卟啉结构与邻硝基苯甲醛选择性关系方程。结果表明：金属离子的Mulliken电荷、静电势和分子的最低空轨道能量是影响邻硝基苯甲醛选择性的主要因素。经实验验证,所建定量结构与选择性关系方程可用于指导设计高选择性的金属卟啉催化剂。     

Continuous gas–liquid aerobic oxidation of toluene catalyzed by [T(p-Cl)PPFe]2O in a series of three stirred tank reactors

The liquid-phase catalytic aerobic oxidation of toluene by [T(p-Cl)PPFe]₂O was studied in a series of three stirred tank reactors. The effects of operation mode (including semi-batch and continuous operation), reaction temperature, catalyst concentration, average residence time, and air flow rate on the oxidation process were examined. The experimental results showed that continuous oxidation had no advantage over the total yield and selectivity of benzaldehyde and benzyl alcohol in comparison with semi-batch oxidation. And the reaction temperature was the most significant factor influencing on continuous oxidation of toluene. It is also found that adopting sequentially decreased temperature in the three series reactors could improve the yield and selectivity of benzaldehyde and benzyl alcohol in this process. Under which at the higher conversion of toluene, the total yield to benzaldehyde and benzyl alcohol increased 17.05% or 43.62% respectively in comparison with adopting sequentially increased or same temperature in the three series reactors.     

金属卟啉催化的甲苯氧化及工艺优化

Catalytic activities of a series of metalloporphyrin complexes in selective aerobic oxidation of toluene were investigated.The effects of different central metal ions in metalloporphyrins[T（p-Cl）PPMCl（M=Fe,Co,Mn,Cu）] on the reaction course had been examined and it was found that T（p-Cl）PPCu presented the highest catalytic activity in the reaction.The reaction conditions of toluene oxidation were optimized by using orthogonal experiment design.Five relevant factors were investigated：temperature,air pressure,catalyst loading,air flow rate and reaction time.The effects of the five factors on both toluene conversion and total yield of benzaldehyde and benzyl alcohol were discussed.The research results showed that the reaction temperature was the most significant factor influencing toluene oxidation.On the basis of the margin analysis,the optimum conditions for the toluene conversion and the total yield of benzaldehyde and benzyl alcohol respectively were achieved,under which the toluene conversion was up to 14.67%and the total yield of benzaldehyde and benzyl alcohol reached 5.89%.     

An efficient oxidation of toluene over Co(II)TPP supported on chitosan using air

An efficient oxidation of toluene to benzaldehyde and benzyl alcohol is accomplished over chitosan(CTS)-supported Co(II)TPP catalyst [Co(II)TPP/CTS] under a relatively mild reaction condition using air in absence of reductants and solvents, it can be reused for five times, with average selectivity of 65%, average toluene conversion of 8.83% and average turnover number of 69804.     

甲苯液相催化氧化过程模拟与优化

Liquid-phase oxidation of toluene with air has become the main technology for producing benzoic acid in a reactor at present. Based on the kinetic model of the toluene oxidation process obtained from laboratory and mass balance of key component, a novel model is established to simulate the industrial toluene oxidation process, in which the effects of benzaldehyde and benzyl alcohol are considered and the kinetic parameters are revised by industrial data. The simulation results show that the error of benzoic acid yield is within 3.5%. Based on the simulation model, to maximize the benzoic acid yield, an optimization model is proposed to optimize the operating parameters, including toluene feed-in mass flux and temperature. The optimization result indicates that on the allowable operating conditions the maximum benzoic acid yield obtained with the reaction temperature at 167.2 C an the mass flux at 104.1 t·h^- 1 is greater than the current one, which can be used to guide industrial reactor s operation.     

Selective liquid-phase oxidation of toluene with molecular oxygen catalyzed by Mn-TiO2 under solvent-free conditions

In this paper, we reported the preparation, characterization, and catalytic performance of TiO₂ doped with Mn for the selective oxidation of toluene to benzyl alcohol and benzaldehyde without any solvent. The structure of the catalyst was determined by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption–desorption analysis (Brunauer–Emmet–Teller [BET]), scanning electron microscope (SEM), transmission electron microscope (TEM), and mapping. The results demonstrated that the catalytic properties of Mn-TiO₂ were higher than those of pure Mn₃O₄ and TiO₂. The effects of reaction temperature, reaction time, oxygen pressure, and the amount of catalyst were studied. Under the optimal conditions, Mn-TiO₂ could afford 6.4% toluene conversion at a combined benzyl alcohol/benzaldehyde selectivity of 58.6%. Moreover, the catalyst can be repeated in the experiment for five times without significant loss of activity.     

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.     

甲苯氧酰化反应制备苯甲醇研究进展

烯烃和芳香烃通过氧酰化反应直接制备羧酸酯具有简单、直接和高效的特点。甲苯通过氧酰化反应制备苯甲醇醋酸酯是该反应的重要应用之一,反应产物苯甲醇醋酸酯和苯甲醇醋酸酯水解生成的苯甲醇是重要的化工原料,工艺路线绿色环保。对甲苯氧酰化反应机理、催化剂组成和载体对催化剂活性的影响、工艺条件的优化以及催化剂失活及再生等方面的研究进展进行综述,现有的甲苯氧酰化催化剂活性较高并可通过再生循环使用,降低了催化剂应用成本。随着苯甲醇醋酸酯、苯甲醇以及苯甲醛等需求的增大和环保要求提高,甲苯氧酰化工艺工业应用前景广阔。     

Aerial oxidation of substituted aromatic hydrocarbons catalyzed by Co/Mn/Br− in water-dioxane medium

Aerial oxidation of substituted aryl aromatic hydrocarbons were carried out using Co/Mn/Br⁻ catalyst system in water-dioxane medium in the range 14–56 bar air and temperature 383–423 K. The combination of optimum catalyst concentration of salts Co(OAc)₂, Mn(OAc)₂ and NaBr (1:3:10 molar ratio) in water-dioxane (1:2 mole ratio) is found catalyze aerial oxidation of substituted aryl aromatic to give corresponding oxygenated products. Under the optimized conditions, p-cymene gave p-isopropyl benzaldehyde (33.1%), p-isopropylbenzyl alcohol (54.7%) and p-isopropyl benzoic acid (3.3%), respectively, at p-cymene conversion 40.2%. Similarly, oxidation of p-methoxy toluene gave p-methoxy benzaldehyde (87.4%), benzyl alcohol (5.5%), and p-methoxy benzoic acid (6%), while oxidation of p-tert-butyl toluene yielded p-tert-butyl benzaldehyde (87%), p-tert-butyl benzyl alcohol (5.7%) and p-tert-butyl benzoic acid (6.1%), at conversions 16.4% and 36.1%, respectively. It is found that Co/Mn/Br⁻catalyst system in water-dioxane medium is effective in the aerial oxidation of substituted aromatic hydrocarbons to get corresponding alcohol and aldehydes in greater yields.     

KINETIC MODELS FOR LIQUID-PHASE CATALYTIC OXIDATION OF TOLUENE TO BENZOIC ACID WITH PURE OXYGEN

The liquid phase oxidation of toluene to benzoic acid by pure oxygen has been performed in a bubble reactor by using cobalt acetate tetrahydrate as catalyst. The influence of the oxygen partial pressures on the reaction kinetics were first investigated, and the results showed that the influence was neglectable in the high oxygen pressure range (>0.5 MPa) under 155°C. Thereby, the reaction rates in the oxidation using pure oxygen are independent of the oxygen partial pressure and expressed as the first order to liquid reactants. Based on a kinetic scheme that involves both benzyl alcohol and benzaldehyde, the kinetic models can well describe the reaction process. Furthermore, the results indicated that the production of benzyl alcohol is much slower than its consumption to form benzaldehyde and the scheme can be further simplified to a kinetic equation, which involves only benzaldehyde as intermediate. The simplified reaction scheme also well describes the reaction, and, thus, the derived kinetic models agree well with the experimental data. The reaction constants follow the Arrhenius law. The estimated activation energies are in the range from 92.63 kJ·mol^?1 to 67.81 kJ·mol^?1.