The Adsorption And Separation Of Volatile Organic Compounds By Metal Organic Framework Materials

Hydrocarbons are important components in volatile organic compounds,and the separation of hydrocarbon compounds is very important in the petrochemical industry.Traditional separation operations are accompanied by huge energy consumption.Adsorption separation of porous materials provides a alternative solution.In the last decades,Metal Organic Frameworks(MOFs)have been considered as the most promising material for the adsorption and separation of sulfide owing to the advantages of the high specific surface area and porosity,adjustable pore size,as well as good thermodynamics and chemical stability.The adsorption and separation behavior of hydrocarbon could be investigated through experiments of absorption and breakthrough.However,lots of MOF materials have been reported and synthesized,if the methods discussed above are adopted to evaluate the adsorption and separation ability of these MOFs,the cost would be high,and the efficiency would be low.In recent years,molecular simulation methods have been employed to screen a large number of MOFs rapidly,the relationship between the structure of MOFs and the adsorption and separation properties could be revealed from molecular level.It also presents a supplement to traditional experimental methods and help us to understand the adsorption mechanism from molecular level.Currently,many studies focus on the adsorption and separation of hydrocarbon mixture in MOFs.The relationship between the structural properties of different MOFs and their adsorption and separation behavior is still unclear.In this dissertation,in order to solve the questions discussed above,Grand Canonical Monte Carlo(GCMC)method was used to study the adsorption and separation behaviors of hexane mixtures as well as the mixtures of propane and propylene in MOFs with different topology and structure,the interaction mechanisms between hydrocarbons molecules and the framewok of MOFs was also discussed.The effect of topological structure on the adsorption and separation performance of hexane isomer mixtures and the mixtures of propane and propylene was revealed.It will provide some guidance for designing MOFs with good separation performance.The major contributions of this work are as follows:(1)The adsorption amount of hexane isomer mixture in Zeolite Imidazolate Framework(ZIFs)at high pressure conditions is as follows:nHEX>2MP?3MP>22DMP?23DMP.Due to its unique pore structure,ZIF-3 has a size-sieving effect on the linear and isoparaffins in the hexane isomers,and thus ZIF-3 shows good separation ability for n-hexane and its isomers(2)The UMCM series MOF has a certain separation ability for the hexane isomer mixture.The adsorption and separation performance of hexane isomer mixture cannot be effectively improved by introducing some functional group to the UMCM series(3)The adsorption amount of each component in propane and propenthe mixtures in the ZIFs increases with pressure until saturation.The saturated adsorption amount of each component in the sample is positively related to the pore size,that is,the larger the pore size,the greater the adsorption amount.ZIF-10 and Cu-BTC show good adsorption performance and excellent working capacity for propane/propylene mixtures at high pressure.At the same time,the material has certain separation ability.