Study On Catalytic Reaction Kinetics Of 1,3-Butadiene Synthesis From Ethanol And Simulation Of Reactor

1,3-butadiene,an essential raw material in the petrochemical industry,is widely used in the fields of the manufacture of synthetic rubber,synthetic resins and fine chemicals.At present in the industrial production practice,1,3-butadiene is mainly obtained from the extraction separation of C4 components from cracking process and the catalytic dehydrogenation of butene or butane,both of which are overly dependent on petroleum resources.In recent years,due to the shortage of petroleum resources and the rapid development of bio-ethanol technology,the production of butadiene by ethanol method has attracted more and more attention from the academic and engineering circles.In this paper,the reaction kinetics of the synthesis of 1,3-butadiene in the second step of ethanol and acetaldehyde were measured in the isothermal micro-integration reactor,based on 2%Zr/MgO-SiO₂catalyst in the two-step process of ethanol to1,3-butadiene developed by our research group.And the reaction kinetic data were obtained.According to the Langumir-Hinshelwood mechanism and the Eley-Rideal mechanism,the corresponding main reaction kinetic equations were deduced.The test results show that for the 2%Zr/MgO-SiO₂catalyst,the aldol condensation rate control step in butadiene synthesis from ethanol and acetaldehyde follows the Langumir-Hinshelwood mechanism.The specific reaction kinetic equations for the main and two side reactions are as follows:（?）In the above formula,the subscript A represents ethanol,the subscript B represents acetaldehyde,the subscript C represents butadiene,the subscript D represents water,the subscript E represents ethylene,and the subscript F represents diethyl ether.On this basis,the effects of reaction temperature,reaction pressure,gas hourly space velocity and ethanol to acetaldehyde molar ratio in feed were explored by using the isothermal flat flow reactor model.The optimized process conditions were obtained.The optimized results were as follows:reaction temperature 603K,reaction pressure 0.25MPa,molar ratio of ethanol to acetaldehyde in feed 3.5:1,gas hour space velocity 1200h^-1.Under these conditions,the selectivity of butadiene was 60.86%,the conversion of ethanol was 9.04%,the conversion of acetaldehyde was 27.08%,and the space-time yield of butadiene was 0.114kg _BD·kgcat^-1·h^-1.The distribution of temperature,pressure,concentration,etc,in the reactor tubes under the optimal process conditions was investigated by using the mathematical model of porous media in the CFD simulation software STARCCM+.The results show that the maximum temperature difference in the reactor tube is only 0.67K,and the temperature distribution is relatively uniform,which will not affect the reaction selectivity due to temperature differences.The above research results can provide some theoretical guidance for the reactor design of 1,3-butadiene synthesis from ethanol.