Simulation Study On The Influence Of Diffusion In The Catalyst Pore Structure On The Reaction Process

Gas-solid catalytic reactions widespreadly exist in the chemical industry.Solidphase catalyst general y has complex multi-level pore structure,which leads to a very complicated process of molecular diffusion and reaction coupling in the catalyst pore.To study the reaction-diffusion coupling law in complex pore and reveal the influence of diffusion on the reaction process is of great significance for the development and optimization of the catalyst.At present,due to the limitation of spatiotemporal resolution,the experimental method cannot deeply study the coupling process of reaction and diffusion in the nano-scale pores.The traditional molecular dynamic simulation of gas diffusion process is inefficient and difficult to couple the chemical reaction process.Therefore,new models and methods are needed to simulate the reaction-diffusion coupling process in the pore.In this paper,the hard sphere-pseudo particle(HS-PPM)coupling algorithm and the simplified lumped reaction model of the methanol to olefin(MTO)process are used to simulate the reaction and diffusion coupling process in the pore of the methanol to ethene and propene conversion process.For the SAPO-34 catalyst commonly used in the industrial MTO process,the catalyst structure with complex multi-level pore is generated on the basis of the random growth method,the porosity,pore diameter and pore volume ratio of the catalyst structure can be independently and quantitatively controlled.The reaction-diffusion coupling process of MTO reaction in the pore was simulated.The effect of catalyst pore diameter,porosity,reactant concentration and activity of catalyst on diffusion and reaction process were analyzed,and the effect of catalyst structure on the reaction and diffusion coupling performance was revealed.The work of this thesis is expected to provide theoretical basis and guidance for the optimization design of MTO catalyst structure and the study of catalyst particle-scale reaction kinetics.