在直径Φ48mm 的鼓泡床反应器中对以醋酸钴(CO~(2+))水溶液为催化剂的甲苯液相空气氧化反应动力学进行了研究。结果表明,反应体系的活性时间随催化剂的用量的增大而线性增大,当 Co 含量大于2×10~(-2)%(mass)时,对反应影响较小。甲苯液相空气氧化反应的甲苯消耗动力学分别与甲苯浓度和氧溶解在甲苯中的浓度成一级反应.其宏观动力学活化能约为41 kJ/mol。氧在液相主体消耗的本征动力学活化能为57 kJ/mol,指前因子53.34m~3/(mol·s)。通过 Ha 数和效率因子η对反应动力学控制步骤进行分析,结果表明,Ha 小于0.1,η为0.606~0.728。反应主要发生在液相主体,受动力学控制,但传质仍对反应有影响。 相似文献
Topics in Catalysis - This study aims to investigate the catalytic activity of spinel-type oxides (NixCoyO4) for the oxidation of toluene and carbon monoxide at low temperatures. A series of Ni/Co... 相似文献
In this study, the porous ultrathin graphitic carbon nitride (CN) nanosheets with rich C and nitrogen defects were prepared by one-step calcining the mixture of melamine and glucose (Glu) in air atmosphere (Glu-CN). Introducing simultaneously rich C atoms and nitrogen defects into CN structures continuously modulates the bandgaps from 2.67 to 1.81 eV of CN photocatalysts. Due to large surface area, more active sites, remarkably longer lifetime of charge carriers and adjustable band gap structure, the prepared ultrathin porous CN nanosheets show the enhanced photocatalytic performance for the degradation of methyl orange (MO) under visible light. The degradation efficiency of optimal CN nanosheet photocatalyst for MO is 5.75 times that of bulk CN. This work provides a facile and universal relevance approach to engineer the band structures of CN by introduction of rich C and porous morphology for high-performance photocatalytic, which can provide informative principles for the design of efficient photocatalysis systems for solar energy conversion.
The production of benzoic acid from toluene in the liquid phase with pure oxygen was studied. Investigations have been carried out with a view to determining the most suitable reaction conditions with respect to operating variables including oxygen flow rate, reaction temperature, batch time and catalyst loading. In a series of batch experiments carried out at 4 atm, the optimum values of mole ratio of oxygen to toluene, temperature, reaction time, and catalyst loading were found to be 2, 157 °C, 2 h and 0.57 g/L, respectively. In addition, a kinetic study was carried out by taking into consideration the optimum reaction conditions. The model dependent on the formation of benzyl radical was found to be feasible for describing the catalytic oxidation of toluene to benzoic acid in the liquid phase. The activation energy was determined as 40 kJ/mol. 相似文献
We conducted the liquid phase oxidation of toluene with molecular oxygen over heterogeneous catalysts of copper‐based binary metal oxides. Among the copper‐based binary metal oxides, iron‐copper binary oxide (Fe/Cu=0.3 atomic ratio) was found to be the best catalyst. In the presence of pyridine, overoxidation of benzaldehyde to benzoic acid was partially prevented. As a result, highly selective formation of benzaldehyde (86% selectivity) was observed after 2 h of reaction (7% conversion of toluene) at 463 K and 1.0 MPa of oxygen atmosphere in the presence of pyridine. These catalytic performances were similar or better than those in the gas phase oxidation of toluene at reaction temperatures higher than 473 K and under 0.5–2.5 MPa. It was suggested from competitive adsorption measurements that pyridine could reduce the adsorption of benzaldehyde. At a long reaction time of 4 h, the conversion increased to 25% and benzoic acid became the predominant reaction product (72% selectivity) in the absence of pyridine. The yield of benzoic acid was higher than that in the Snia‐Viscosa process, which requires corrosive halogen ions and acidic solvents in the homogeneous reaction media. The catalyst was easily recycled by simple filtration and reusable after washing and drying. 相似文献
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. 相似文献