Study On Trickle Bed Reactor For One-step Synthesis Of Methyl Methacrylate Prepared By Methylacrolein

The one-step methacrolein synthesis of methyl methacrylate is a very promising process route,and the development of an efficient reactor is a key link to achieve large-scale industrialization of this route.The trickle bed reactor has a flow characteristics close to plug flow,with a low degree of backmixing,high conversion rate and selectivity,and is particularly suitable for the one-step synthesis of methyl methacrylate.However,the complicated gas-liquid-solid three-phase catalytic process is involved in the trickle bed reactor,and the design and development of the reactor is still difficult.This subject uses Computational Fluid Dynamics(CFD)to simulate the fluid flow in the trickle bed reactor,to achieve the prediction of the reactor bed pressure drop and liquid holding capacity;through the phase equilibrium experiment to obtain the lack of reactor design process thermodynamic parameters;using the process simulation software Aspen Plus to optimize the process conditions of the one-step synthesis of methyl methacrylate in trickle bed reactor to achieve the preliminary design and development of the reactor.The bed structure characteristics and internal fluid flow laws of the trickle bed were systematically studied.Discrete element method(DEM)was used to construct the catalyst particle bed structure with different shapes and sizes,and the structural characteristics of the catalyst bed layer were obtained.The volume of fluid(VOF)method was used to simulate and calculate the multi-phase flow process in the trickle bed.The local gas-liquid flow process was quantitatively described,and the hydrodynamic parameters of the trickle bed reactor were predicted.Based on the calculation results,the pressure drop and liquid holding capacity empirical formulas were revised,and the hydrodynamic model parameters of the trickle bed reactor were improved.The vapor-liquid equilibrium process involved in the trickle bed reactor was systematically studied.By designing a binary vapor-liquid phase equilibrium experiment,the vapor-liquid phase equilibrium data of methacrylaldehyde-methanol was obtained.By fitting the parameters of different thermodynamic models,the binary interaction parameters of methacrylaldehyde-methanol were obtained,which supplemented the thermodynamic data missing in the calculation of gas-liquid equilibrium,and improved the thermodynamic model parameters of the trickle bed reactor.By coupling the key parameters of hydrodynamics,thermodynamic binary interaction parameters and the kinetics of oxidative esterification reaction,a trickle bed reactor model of industrial scale methyl methacrylate one-step synthesis was constructed.The flow field distribution of the trickle bed reactor was systematically studied,and the simulation prediction of the trickle bed reactor was realized.Through the optimization of process conditions,the effective control of the temperature in the trickle bed reactor and the preliminary design and development of the industrial scale trickle bed reactor were achieved.