The Effect Of Ion Exchange Resin Catalyst Pore Structure On Mass Transfer And Catalyst Performance

Catalytic distillation technology is a very important chemical operation unit in the chemical production process.It separates the catalytic reaction from the rectification in the same distillation column.It is a new coupling of the separation and reaction to strengthen the catalytic process.Catalytic distillation has the advantages of high efficiency,energy saving,and continuous production.However,the catalytic distillation process is often limited by the mass transfer and heat transfer in the rectification column,which affects the further improvement of catalytic distillation efficiency.So far,many scientists have conducted in-depth studies on the catalyst packing method in the catalytic distillation tower and the mass transfer performance of the tower device.The flow pattern of the fluid in the column was optimized by means of CFD simulation and other methods,which promoted the mass transfer between the towers,but the smallest catalytic unit in the catalytic distillation tower was the catalyst particles.Many catalysts have been proven to have high catalytic activity so far,but the internal mass transfer of the catalyst particles,on the other hand,limits the high catalytic activity of the catalyst.Therefore,the mass transfer rules on the catalyst particles are explored to increase the individual catalyst particles.The mass transfer efficiency is beneficial to increase the catalytic efficiency of the catalyst particles and further increase the catalytic efficiency of the entire catalytic distillation tower.Therefore,this paper will use ion exchange resin catalysts commonly used in catalytic distillation processes as the research object.The styrene-divinylbenzene ion exchange resin polymer microspheres with different structures were synthesized by varying the amount of cross-linking agent and the amount of porogen used,and the benzene-divinylbenzene ion exchange resin polymer microspheres were synthesized by the nitrogen adsorption-desorption method,the mercury intrusion method,and the scanning electron microscope.The structural characterization of the internal skeleton of ethylene-divinylbenzene polymer microspheres was performed.The results of characterization analysis show that the total internal porosity of the polymer changes little when only the cross-linking agent is changed,but the cross-linking agent has a greater impact on changing the average pore size of the mesopores and macropores inside the polymer.When the content of crosslinker is constant,changing the content of porogen has a great influence on the porosity of the internal structure of the polymer.In Chapter 2,the seven samples were synthesized and characterized,toluene was used as an adsorbate molecule.We conducted isothermal adsorption experiments and kinetic adsorption experiments on the polymer.We conduct isothermal adsorption experiments and kinetic adsorption experiments on polymers.Through experiments,we have found that the adsorption of toluene molecules within the polymer conforms to the Freundlich isothermal equation,while the adsorption of toluene molecules on the polymer is an intermolecular force under van der Waals forces.Afterwards,the effects of surface diffusion coefficients and volume diffusion coefficients under different pore structures were explored using toluene molecules as probe molecules.Through experiments,we conclude that the volume diffusion coefficient and the surface diffusion coefficient increase with the increase of the average pore size ratio of the mesopores.With the increase of the porosity and the average pore size,the volume diffusion coefficient and the surface diffusion coefficient are both With it increases.However,the volume diffusion coefficient increases with the porosity and the average pore size.In the 4 chapter,through the sulfonation reaction,the sulfonic acid group is attached to the benzene ring of the polymer microspheres to make them have the catalytic ability.In order to determine the optimal time for the sulfonation reaction,it was determined experimentally that the sulfonic acid group could be sufficiently attached to the polymer by 3h.The sulfonated polymer ion exchange resin was characterized by subsequent Fourier infrared spectroscopy,elemental analysis,and the like.By characterization we can conclude that the amount of crosslinking agent increases with the amount of porogen used.The content of sulfonic acid groups in the ion exchange resin is reduced,this is due to the increase in the degree of cross-linking,while the relative decrease in the proportion of styrene can provide a reduction in the number of benzene rings participating in the sulfonation reaction,and in the case where the amount of the cross-linking agent is constant and the amount of the porogen is increased,the polymer ion exchange is performed.The sulfur content of the resin does not change much.Subsequently,through the hydrolysis experiment of methyl acetate on the synthetic ion-exchange resin,the catalytic performance of the catalyst was evaluated through the reaction kinetics experiment.Through experiments,we conclude that the performance of the synthesized catalyst decreases as the degree of cross-linking increases.This is due to the fact that The reaction takes up the dominant position during the catalytic reaction;when only the content of the porogen is changed,the amount of sulfonic acid groups that can be fixed at this time is constant,and the catalytic performance of the catalyst increases as the amount of the porogen increases.When the mass transfer performance dominates,this is due to the increase of porogen to increase the internal porosity of the polymer,the average pore size and other parameters.Finally,several commercial ion exchange resins were compared.Amberlyst-46 has the highest catalytic activity.Amberlyst-15 has the worst catalytic performance.The performance of several synthetic ion exchange resin catalysts is similar to the catalytic performance of C100E.Structural characterization of commercially available ion exchange resins revealed that commercial resins with better catalytic activity all contained larger porosity and larger average pore size of macropores,followed by commercial resins with less mesopores or mesopores structure.