Comparative Study of Homogeneous and Heterogeneous Modelling of Water-Gas Shift Reaction with Macro-or Micro-kinetics

Abstract

This paper presents critical studies on water-gas shift reaction (WGSR) kinetic models as well as the modelling approaches of the reactor, in which the reaction is conducted – the packed-bed tubular reactor (PBTR). There are two different types of models often used to represent the WGSR kinetics: (1) macro-kinetics and (2) micro-kinetics types. The PBTR models can be divided into homogeneous and heterogeneous types. There have been lots of positive and negative arguments regarding the use of different models for the WGSR reactor simulation and design. So far, no solid evidence regarding which form of kinetics model is considered to be the most accurate and suitable for reactor design and simulation. Answering this question is the main objective of this paper, where several major kinds of kinetic-reactor models are compared based on the same Cu (111) catalyst. The different models are used to predict the CO conversion of the shift reactor and their accuracies are compared against a reported experimental data. The analysis shows that the micro-kinetics gives better accuracy than the macro-kinetics model. Interestingly, the results show that the macro-kinetics model used in the homogeneous reactor modelling can give prediction as accurate as that of the more complex micro-kinetics model provided in the former case, the transfer limitation correction factor is included. The comparison among these different models shall provide a better understanding on the selection of model form when it comes to designing the reactor involved.