Study On Adsorption Performance Of Carbon Dioxide On Zeolite Under Multi-physical Fields

Masses of greenhouse gases have been released into the atmosphere,which lead to the global warming.Carbon dioxide is the most important one among various greenhouse gases for its long persistence and high content in the atmosphere.The content of carbon dioxide is also especially important for those who work and live in closed environment.Therefore,the separate and removal of carbon dioxide has significant meanings and gets more and more common attentions.Among vast separate and removal methods of carbon dioxide,the adsorption method has become a very popular way because of its advantages like mild operating conditions,low energy consumption,fast absorption rates,simple regeneration and the stable performance.Zeolites are crucial and effective adsorbents of carbon dioxide,and 13X zeolites have a stronger ability to adsorb carbon dioxide than other zeolites for their bigger effective size of pores,which contain vast sodium cations.So 13X zeolites are chosen as materials for experiment and simulation in this thesis.Models of 13X zeolites and carbon dioxide are established and simulated to modify and verify the force field with actual adsorption values.Adsorption capacity and sites are simulated by Monte Carlo method.The simulation results show that the isothermal adsorption curve of carbon dioxide adsorbed by 13X zeolites conforms to type I adsorption curve.The adsorption of carbon dioxide at low pressure occurs mainly in the small pores and the sites around the sodium cations,while the increase adsorption of carbon dioxide at high pressure occurs mainly in large pores.The growth speed of adsorption capacity slows down with the increase of pressure.Adsorption capacity and sites of carbon dioxide adsorbed on 13X zeolites at different temperatures are also simulated by Monte Carlo method.The simulation results show that the adsorption capacity of carbon dioxide decreases with the increase of temperature.The adsorption sites of carbon dioxide are concentrated at low temperature,while they are dispersive at high temperature.Chamber experiment system is designed and established to test the adsorption of carbon dioxide at different temperatures.The experiment results show that the lower the temperature is,the stronger the adsorption capacity will be,but it will cost longer time to get adsorption balance.The higher the temperature is,the weaker the adsorption capacity will be,and it will cost shorter time to get adsorption balance.The interaction between carbon dioxide and the cage structure of 13X zeolites under different electric fields is simulated by density functional theory.The simulation results show that the adsorption energy of carbon dioxide and the cage structure model decreases after adding an electric field.With the increase of electric field,the adsorption energy is decreasing,but the trend is slowed down.After adding an electric field,the amount of transfer charges between carbon dioxide and the cage model is also decreasing.Adsorption of carbon dioxide under electric field is tested after modifying the chamber experiment system.The experiment results show that the adsorption capacity of carbon dioxide adsorbed on 13X zeolites is weakened by the adding electric field.With the increase of electric field,the desorption rate of carbon dioxide increases,and the amount of desorption is also improved.This paper analyzes the simulations and experiments about adsorption capacity of carbon dioxide under different pressures,temperatures and extra electric fields and study about adsorption under multi-physical fields at the macro and molecular level.The conclusion has the extensive reference value in the development of absorption and desorption of carbon dioxide on zeolites.