Synthesis Of Metal-organic Frameworks(MIL-53) And Adsorption Of Toluene

Volatile organic compounds（VOCs）have attracted wide attention in recent years as one of the precursors of ozone in environmental air,it had became one of the hot spots in the pollution control of atmospheric environment.Based on the existing research,the adsorption method is the most mature and widely used in gas processing,and the core of the adsorption effect lies in the adsorbent.As a new type of porous material,the metal-organic framework material has a large specific surface area and a regulatable pore structure that can be used as a potential adsorbent for VOCs.In this paper,a series of MIL-53（Al）were synthesized by solvent-thermal method.Through BET,XRD and other characterization methods,the effects of different reaction conditions on the pores structure and morphology of MIL-53（Al）were investigated.Furthermore based on the breakthrough curves of toluene,the adsorption equilibrium and adsorption kinetics of toluene adsorbed by MIL-53（Al）were studied.And the results are as follows:1.BET specific surface area characterization results showed,the reaction temperature,reaction time,reactant anion and reactant ratio all had a great influence on the pore structure and morphology of MIL-53（Al）material.The specific surface area and pore volume of the MIL-53 sample reached 1165.4 m²/g and 1.436 cm³/g respectively after activation modification of roasting.2.The optimal reaction conditions had been determined:the reaction temperature is190°C,the reaction time is 72 h,aluminum nitrate is the aluminum source,Al（NO₃）₃:H₂BDC=1:1.5.Moreover,after activation modification,the static saturated adsorption capacity and the dynamic adsorption capacity of toluene on MIL-53（Al）could reach 391.25mg/g and 289.14mg/g respectively.3.To some extent the static adsorption of toluene by the sample would increase with the enlargement of the specific surface area and the total pore volume,and showed a linear relationship.4.In the dynamic process of toluene adsorption on MIL-53（Al）,the pseudo-second-order kinetic model was fitted for describing the dynamic adsorption process of toluene on MIL-53（Al）.The Langmuir isotherm equation was more suitable to describe the adsorption process of toluene on MIL-53（Al）.The adsorption of toluene on MIL-53（Al）was mainly based on monolayer adsorption.The particle diffusion model fitting results showed the adsorption rate of toluene adsorption on MIL-53（Al）was mainly determined by the internal diffusion process,but the adsorption process was also affected by the external diffusion and surface adsorption processes.The adsorption of MIL-53（Al）to toluene was mainly based on physical adsorption,and there was a part of the chemical adsorption process.