Kinetics of Coke Formation on a Fe-ZSM-5 Zeolite Catalyst in the One-Step Oxidation of Benzene to Phenol with N2O

The coking behavior of the Fe-ZSM-5 zeolite catalyst during the oxidation of benzene with N2O to phenol was studied in an isothermal fixed-bed reactor using thermogravimetry. The effect of reaction time and temperature as well as the molar ratio of reactants on coking was investigated. Based on information obtained from experiments and a gas chromatography-mass spectrometry analysis of the coke on the catalyst, we suggest a mechanism for coke formation. Results show that the formed coke mainly comes from the further oxidation of phenol, revealing that sequential deactivation occurs in the main reaction. Based on the suggested mechanism, a kinetic model for coke formation that describes coke deposition over the Fe-ZSM-5 zeolite catalyst was developed. A statistical test and a residual distribution analysis show that the kinetic model established here is in good agreement with the experimental data and is acceptable and reliable.

摘要：采用等温固定床反应器和热重分析相结合的方法研究了 Fe-ZSM-5 分子筛上 N2O 一步氧化苯制苯酚的积炭行为, 考察了反应时间、温度和原料配比对积炭量的影响. 依据实验现象和积炭物组分分布的气相色谱-质谱分析结果, 提出了 Fe-ZSM-5 分子筛上 N2O 一步氧化苯制苯酚的积炭机理. 结果表明, Fe-ZSM-5 分子筛上的积炭物种主要来源于氧化产物苯酚的深度氧化, 属连串失活. 基于所提出的积炭机理和实验结果, 建立了 Fe-ZSM-5 分子筛催化剂的积炭动力学模型, 统计检验和残差分布检验表明, 所建模型与实验结果相容, 可靠性强. 

The mechanism for the coke formation on Fe-ZSM-5 in the oxidation of benzene to phenol with N2O was investigated. The coke mainly came from further oxidation of phenol, and the kinetic model for coke formation was developed.Figure optionsDownload as PowerPoint slide