Exploring the Correlation between Structure Properties and Methane Adsorption of Metal-Organic Frameworks
Date Issued
2015
Date
2015
Author(s)
Wang, Wen-Hao
Abstract
In this study, we employ simulation methods to build and calculate density(D)、volumetric surface area(VSA)、gravimetric surface area(GSA)、specific pore volume (SPV)、void fraction(VF) and pore size(PS) of thirty-eight types of metal-organic frameworks (MOFs) and explore the correlation between these structural properties and methane volumetric adsorption capacity at 65bar and 298K in MOFs. We find that VF、PS and GSA mainly correlate methane adsorption capacity, especially of pore size. MOFs with high methane adsorption capacities have smaller pore size and the optimal pore size is in the range 5-13 Å.The geometry size of organic linker mainly affect MOFs’ pore size. We also find that expanding tritoptic carboxylate linkers with benzyl or alkyl chains will makes MOFs’ pore size beyond optimal range. Consequently, MOFs with tritoptic carboxylate linkers are hard to enhance methane volumetric adsorption capacity through modifying its organic linkers. However, expanding tetratopic carboxylate linkers with one to two benzyl or alkyl chains still maintains MOFs’ pore size in optimal range. In addition, introduction of pyrimidine groups into the tetratopic carboxylate linkers can increase the dynamic freedom of linkers and thus improve adsorption performance. This kinds of MOFs can reach methane volumetric adsorption capacities up to about 240 (cm3(STP)/cm3) and thus are promising candidate MOFs materials.We build multilinear regression models for predicting the methane adsorption capacity at 65bar and yield following reasonable model: According to this model, small pore size、suitable gravimetric surface area and high void fraction are necessary structural conditions for high methane volumetric adsorption capacity at 65bar in MOFs.
Subjects
Metal-Organic Frameworks
Methane
Structure-Properties
Type
thesis
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