Unsteady-state kinetic simulation of naphtha reforming and coke combustion processes in the fixed and moving catalyst beds

Abstract

The work is dedicated to the construction of kinetics models for the naphtha reforming process and the adjacent process of catalyst regeneration by coke combustion. The proposed kinetic model for the reforming process is based on the use of common rate equations for the groups of similar reactions with account of difference in reaction rates for individual homologs within these groups by simple correlations with thermodynamic properties (first of all – with the values of Gibbs free energy) of individual reactions and by other simplification methods. Such approach gives the way to construct the kinetics models optimal from the point of view of compromise between accuracy and simplicity. The proposed naphtha reforming model is characterized with the high level of kinetic scheme detailization (62 individual and group reactants and 146 individual reactions), at the same it is rather simple and provides the accurate description of the experimental data using only 22 kinetic parameters. This model is thermodynamically consistent and provides accurate description of experimental data in a wide range of process parameters. Account of catalyst deactivation by coke deposition in the model gives the way to simulate transient reforming process performance both in fixed and moving catalyst beds. Kinetics of coke combustion for catalysts with moderate coke content (up to 3% mass) may described by simple kinetic equation with apparent reaction rate orders closed to unit for relative coke content and to 1/2 for oxygen. Demonstration simulations of naphtha reforming and coke combustion processes are presented.