Study On Reaction Kinetics Of FBD Water-gas Shift Reaction Catalyst

The high temperature water-gas shift reaction(WGSR) over an industrial FBD catalyst was investigated by intrinsic kinetics, global kinetics experiments in isothermal conditions and at elevated pressures, and by the effective diffusion coefficient experiments in dynamic state. The isothermal integral tubular reactor and inner gradientless reactor were used to produce intrinsic kinetic and global kinetic data for power-law kinetic models, in conditions of temperature from 300℃～460℃ , pressure from 0.8Mpa～2.8 MPa, and space velocity from 7000h-1～9000 h-1. With the estimation methods, two power-law kinetics models were obtained. And the accuracy of experimental data and calculated model were verified by F-test, correlation index test. The dynamic state method-single pellet string reactor method (SPSRM) was employed to determine the effective diffusion coefficient of FBD shift reaction catalyst. The parameter estimation method was applied to get the effective diffusion coefficient from the experimental data, so the tortuosity factor can be calculated. The tortuosity factor of FBD catalyst is 2.95. Five representative kinetics models proposed in literature had been discriminated by reduced rate method which is based on the effect of total pressure upon the reduced rate rR. The reaction rate, from which the experimental values of reduced rate were obtained, had been measured experimentally on an internal circulating gradientless reactor at 425℃ in the pressure range 1.0~2.81MPa and with the same conversion gas. On the other hand the experiments verifying the content of conversion gas were performed in an isothermal integral reactor so as to estimate the parameters in five models and to gain the calculated values of reduced rate. The results of discrimination manifested that the calculated values of reduced rate of power-lower model coincide with the experimental values, and it showed that is the most appropriated equation. And the reliability of power-law kinetic equation has been proved again. The effect of pressure on CO conversion rate over FBD ,B116 ,C12-4 WGSRcatalysts was examined, by intrinsic experiments, original particle size experiments and life-time testing experiments. It showed that the elevated pressure had big effect on CO conversion rate in WGSR, but the influence of inner diffusion of original particle size catalyst could reduce the effect. The result of life-time testing experiment also showed that the influence of inner diffusion can not be neglected. All these proved that character of catalysts in elevated pressure is more similar with character used in plants. For this reason, kinetics experiments for WGSR catalyst were proposed on wide range pressure.