Molecular-scale Macroscopic Reaction Kinetics Of Catalytic Cracking Of C4 Olefin

Light olefins play an important role in the petrochemical industry,and they are the raw materials for many chemical products.By the attention of various countries.Catalytic cracking process is one of the main processes for producing light olefins.Compared with the traditional thermal cracking process,it can reduce the reaction temperature,improve the selectivity of olefins,and enhance the adaptability of raw materials,so it has received extensive attention.At present,the catalytic cracking of olefins has the characteristics of complex reaction network and unclear mechanism.Under this background,it is particularly important to study the fine reaction network of catalytic cracking of olefins and build a kinetic model for the development of catalytic cracking processes of olefins and the design of reactors.In this work,a fine molecular-scale olefin catalytic cracking reaction pathway is proposed,and a molecular-scale macroscopic reaction kinetic model is constructed on this basis.In this work,using n-butene as a model compound,the reaction mechanism of its catalytic cracking reaction on industrial HZSM-5 catalyst was studied.After obtaining the initial macroscopic reaction path,the n-butene catalytic cracking was further combined with the microscopic reaction kinetics and simulation.reaction rules.And wrote reaction rules,using the algorithm of automatic generation of chemical reactions,successfully realized the generation and visualization of the reaction network,established a fine reaction network containing 39 reactions and a macroscopic reaction kinetic model at the molecular scale,and obtain kinetic equations and solve differential equations.The study found that in the conversion of n-butene,isomerization occurs first at lower temperature,and the degree of double bond isomerization is greater than that of skeletal isomerization.As the temperature increases,further dimerization,beta cleavage,etc.occur.The subject research has discovered a new pathway for dimerization to produce isomeric C₈+（or isomeric C₈ alkenes）,thereby further promoting the cracking reaction.In addition,a macroscopic kinetic model at the molecular scale was constructed,the kinetic parameters in the model were calculated by genetic algorithm,and sensitivity analysis was performed.