Kinetic Study Of Acetylene Acetoy Lation Catalyst And Numerical Simulation Of Reactor Based On CPFD

Vinyl acetate is a high value-added organic chemical raw material.Due to its molecular structure containing unsaturated vinyl groups,strong polymerization ability,and active chemical properties,it can be widely used in the production of polyvinyl alcohol compounds.China’s energy resource structure is rich in coal,poor in oil,and less in gas,and the cost of coal development and utilization is relatively low,as well as the advantages of high product quality and simple process of acetic acid synthesis by acetylene gas-phase method,the acetic acid industry has developed well.The tubular fixed bed reactor is commonly used in the acetylene gas-phase process to synthesize acetic acid.Compared with fluidized bed reactors,the tubular fixed bed reactor has a simple structure,uniform bed cross-section temperature,large production capacity,and is widely used in strong exothermic reaction processes.However,the flow field characteristics and transfer properties inside the reactor are not clear,and it is necessary to systematically study the flow,heat transfer,and chemical reaction processes inside the reactor to address issues such as catalyst sintering and reduced activity caused by high temperature in the reactor.This paper mainly includes the following three parts.（1）The catalyst used in this chapter was a well-performing catalyst developed by the research group.The Zn/NC catalyst was prepared by impregnation method,and suitable zinc acetate and pyridine molar ratio were selected through performance testing.The superior catalyst was then applied to the study of the kinetics of the acetylene acetic acid reaction.To eliminate the effects of internal and external diffusion,the design of reaction kinetics experiments was carried out.Through the derivation and selection of the reaction mechanism model,the kinetic model was fitted using Matlab software,and finally the reaction kinetics model was obtained.（2）The simulation of gas-solid flow in a fixed bed reactor using Barracuda software shows that the raw gas enters the bed layer from top to bottom,and after contacting the catalyst,a certain pressure drop occurs due to the obstruction of the catalyst particles.After the reaction gas enters the bed layer,the bed pressure gradually decreases,and the highest pressure drop can reach 30,000Pa.Increasing the particle size appropriately can alleviate the bed pressure drop.（3）The obtained chemical reaction kinetics model was added to the software for gas-solid-chemical reaction coupling.The effects of particle size,temperature,feed gas velocity,and acetylene acid ratio on the reaction results were studied.The results show that when the catalyst particle size is about 6 mm,the bed pressure drop is significantly reduced.When the bed temperature is around 180℃,the rate of temperature increase in the reaction tube is significantly reduced.When the gas velocity is 1.5-2 m/s,the bed temperature can be significantly alleviated,and the occurrence of high-temperature flyover can be greatly reduced while ensuring the product conversion rate.Through the three-factor experiment of temperature,feed gas velocity,and acetylene acid ratio,the effects of these factors on the reaction and their mutual influence were explored.The optimal operating parameter conditions were found to be A₃B₁C₂,with the reaction temperature set at200℃,the inlet gas velocity at 1 m/s,and C₂H₂/CH₃COOH at 6:1.