Kinetics of Benzene Hydroalkylation over Bifunctional Catalyst Ru/Hβ

Abstract

The bifunctional catalyst Ru/Hβ was prepared by equal volume impregnation method and applied to the study of the kinetics of benzene hydroalkylation reaction. The reaction order of 1 for benzene and 1.94 for H₂ (\({P}_{{H}_{2}}\le 3\text{ MPa}\)) was obtained by fitting the kinetic experimental data first. Then a kinetic model conforming to the Eley–Rideal (E–R) mechanism was developed based on the types of adsorbates on different active centers of the solid catalyst, and the main mechanism was that the benzene in the adsorbed state was partially hydrogenated to produce cyclohexene, which was not desorbed from the active centers. Some of it was further hydrogenated to produce cyclohexane, and some was alkylated with benzene in the bulk phase to produce cyclohexylbenzene. The reaction rate control step was the alkylation of benzene and cyclohexene. The model parameters were calculated using a genetic algorithm. The model was tested to be able to describe the reaction mechanism of benzene hydroalkylation well and to provide guidance for process optimization.

Graphical Abstract

Benzene hydroalkylation is a key starting step in the process of preparing phenol by the cyclohexylbenzene method instead of HOCK method, and there is a great lack of related kinetic studies. In this paper, the bifunctional catalyst Ru/Hβ was prepared and applied to the study of the kinetics of benzene hydroalkylation reaction. A kinetic model conforming to the Eley-Rideal (E-R) mechanism was developed. The model parameters were calculated using a genetic algorithm. The model was tested to be able to describe the reaction mechanism of benzene hydroalkylation well and to provide guidance for process optimization.