Determination and Application of Improved Kinetic Parameters for Simulation of Maleic Anhydride Synthesis in Industrial Fixed-Bed Reactor

Abstract

The aims of this study were to determine improved kinetic parameters in five kinetic models for oxidation of n-butane into maleic anhydride in an industrial fixed-bed reactor, and to simulate the reactor performance. On the basis of the measured process parameters, inlet and outlet concentrations of n-butane were calculated and then used to fit the kinetic models. The industrial fixed-bed reactor was approximated by 10 continuous stirred tank reactors (CSTR) connected in series. Based on the calculated outlet concentration of n-butane from the industrial reactor, the outlet concentration of n-butane from the penultimate reactor was calculated. Then the concentrations of n-butane were calculated until the inlet concentration of n-butane in the first reactor was obtained. Kinetic parameters were determined by comparing the inlet concentrations of n-butane in the first reactor with the inlet concentration of n-butane obtained on the basis of the measured process parameters ​​in the industrial fixed-bed reactor. Kinetic models with improved kinetic parameters showed better simulation results compared to kinetic models with the existing kinetic parameters. The best agreement of simulation results and measured values was achieved with application of the kinetic model 2 (Equations (2a-c)). The smallest deviations of numerical simulation in comparison with measured values of the outlet pressure of reaction mixture were 0.45, 0.75 and 0.75% for application of the kinetic model 3 (Equations (3a-c)). The percentage deviations of numerical simulation with improved kinetic parameters and the existing kinetic parameters in comparison with measured values of inside reactor temperature were in the range 0.90-5.36% and in the range 4.17-9.78% (kinetic model 2, Equations (2a-c)), respectively.