Adsorption Simulation Of Benzene Series On Aluminum Based Metal-organic Frameworks

The emission of benzene series has always been a hot topic in industry,while traditional adsorbents at present can not satisfy the increasing demand of VOCs treatment,hence it is necessary to develop and explore new kind of adsorbent to deal with the VOCs pollution problems.Metal-organic compound(MOF)is a new kind of porous material,most of which possess some merits that are in favor of adsorption: large surface area,big pore volume,small density,regular aperture and abundant pore structures.Among them,Al-MOF are less expensive and environmental friendly compare to other MOFs,therefore,Al-MOF have a bright future in adsorption field.However,few literatures have reported the application of Al-MOFs in VOCs treatment so far.In this work,the adsorption behaviors of benzene,toluene and p-xylene in eight Al-MOF(CYCU-3?CAU-3-NDC?MOF-519?MIL-101?MIL-68?CAU-3-BDC?MOF-520?MIL-100)have been studied,including adsorption capacity,adsorption energy,preferential adsorption sites and diffusion coefficient.First,grand canonical Monte Carlo(GCMC)simulation was used to study the adsorption characteristics of benzene series in eight Al-MOF at 298 K.The comparison between simulation results and experimental data demonstrates that Dreiding force field is eligible to describe the benzene series and Al-MOF adsorption system.Abundant pore structures and large pore volume of Al-MOF lead to higher adsorption capacity than traditional adsorbents,among eight Al-MOFs,MIL-101 and CYCU-3 possess the highest adorption capacity for benzene series which reach about 1000mg/g~1400mg/g?Second,preferential adsorption sites were analyzed according to snapshots and density distribution of adsorbates.Results show that the adsorbates tend to gather in smaller pore structures when the adsorbed amount is small,then adsorbates show up in larger pores as the adsorbed amount increases.In addition,the study of adsorption energy shows that metal cluster and organic linker are preferential adsorption sites,and the adsorption energy become stronger as the number of methyl increases.Furthermore,diffusion coefficient of different adsorbate at 298 k was also compared,it was found that diffusion coefficient decreases as the number of methyl group increases.Pore structure has a strong influence on diffusion coefficient,infinity pore structures along one direction is favorable for diffusion.In the end,the effect of Al-MOF's physical properties on adsorption capacity of benzene was investigated,results display that the BETsuface area and pore volume of Al-MOF have linear positive correlation with adsorbed amount of benzene series,and the density of Al-MOF have linear negative correlation with adsorbed amount of benzene series.These conclusions can provide guidance for MOFs application in VOCs adsorption field in the future.