Most of researches for kinetic analysis of methanol synthesis are carried out for gas-solid phase reactors except for Wedel's which was performed in slurry reactors. The purpose of this study is to propose a kinetic model of methanol synthesis in slurry reactors. The kinetic model of Langmuir-Hinshelwood type is proposed assuming that there is no reversible reactions, methanol is synthesized from hydrogenation of CO and $CO_2$, and there are two kinds of active sites. $H_2$ and $H_2O$ are supposed to be competitively adsorbed on one site, and CO, $CO_2$, and $CH_3OH$ on the other site. The assumptions are based on the arguments that the effect of methanol on the kinetics is negligible in the experimental conditions, methanol can be synthesized from both CO and $CO_2$, and dual site Langmuir-Hinshelwood mechanism from the results of Dybkjaer(1985), Herman et al.(1979) Matulewicz(1984). In order to accurately calculate concentration of each component in liquid phase, the behavior of gas mixture is studied based on Peng-Robinson equation of state.
Concentrations in pseudo-equilibrium are estimated by the following algorithm. Experimental data from "Mass Transfer in the Liquid-Phase methanol Synthesis $(LPMeOH)^TM$ Process" are taken for the initial values for composition in gas phase. Then, liquid compositions, which is in physical equilibrium with the prescribed gas compositions, are estimated using Peng-Robinson equation of states, laws of Henry and Rewis, and two parameter Margules model. After physical equilibrium is established, it is assumed that chemical reactions occur only in liquid phase. The chemical reactions cause the liquid composition to change, and ultimately the gas phase composition. This procedure is iterated until the changes in the composition in both gas and liquid phases are less than a given tolerances. Because the thermodynamic equilibrium is not unaffected by the catalyst, the presence of it is not taken into consideration.
From pseudo-equilibrium concentrations, which are estimated by the iterations, in the liquid phase the variables of proposed kinetic model for methanol synthesis are estimated by the random search method. The results of the proposed model are compared with those of experiment.
