Reaction−Diffusion Model for Irregularly Shaped Ammonia Synthesis Catalyst and Its Verification under High Pressure

Abstract

A one-dimensional isothermal multicomponent reaction−diffusion model was established for irregularly shaped ammonia synthesis catalyst A301. The intrinsic kinetics equation was derived from the experimental data obtained under high pressure ranging from 7.5 to 10.5 MPa. A feasible method was developed to measure the shape factor of the irregularly shaped ammonia synthesis catalyst. The dynamics single pellet string reactor method as well as parameter estimation was applied to get the tortuosity factor of irregularly shaped ammonia synthesis catalyst. The orthogonal collocation method combined with the Broyden method was employed to solve the model equations, and the internal-diffusion efficiency factor and the concentration distributions of individual components in the catalyst were obtained. The multicomponent reaction−diffusion model was verified by the global kinetics data obtained in a gradientless reactor. The calculation data agreed well with experimental data, so the model can be used to describe t...