Computational Study On Industrial Gas Storage And Separation Performance Of Nanoporous Materials

Porous framework materials with high specific surface area,high porosity,rich topologies,designable pores structure,and controllable properties,have promising applications in the fields of gas storage and separation.Chemically,the possible types of porous framework materials are infinite,and thus it is very difficult to study one by one experimentally for a given application.Therefore,we introduced the methodology of Material Genomics,combining high-throughput calculation and special digital database,to study the gas storage and separation performance of two kinds of porous framework materials,MOFs and COFs:(1)We firstly built an experimental-synthesized COF database,and shared it on website.According to the idea of "similar compatibility",we considered that COFs with pure organic properties have advantages for the capture of non-polar molecules.Therefore,we applied those COFs to the storage of radioactive iodine and methyl iodide,which often appear in nuclear industry and nuclear combustion waste.Guided by the structure-performance relationship,we successfully designed a better material for iodine capture.(2)Guided by the idea of Material Genomics,we proposed a concept named "genetic structural unit",that is structural units with chemical reaction sites for dividing material genes,and a "quasi-reactive assembly algorithms" was proposed by mimicking the natural growth process in the synthesis process of COF materials.By developing high-throughput crystal assembling program,471,990 COF materials were constructed,which greatly enriched the number of COF and topology types.For 2D-COF materials,we proposed a "self-adaptive algorithm" to provide an effective layer spacing control method for high-throughput assembly of 2D-COF materials,while for 3D-COF materials we found a large number of materials with new topologies.The material genomics approach proposed in this work enables high-throughput construction of COFs,and providing powerful guidance for material design,new topology discovery,and experimental synthesis of COF materials.(3)In order to verify the usefulness of material genomics method for high-throughput construction of COF database,we perform large scale computational screening for vehicle methane storage and xylene isomers separation.The trade-off effect between volumetric and gravimetric working capacity in methane storage is found.COFs with both high volumetric and gravimetric working capacity in our database were identified owning to the merits of low skeleton density of COFs.By screening COFs for xylene isomers separation,COFs with specific pores that can automatically recognize p-xylene molecules were found,and thus breaking the trade-off effect on adsorption capacity and selectivity to obtain materials with both high selectivity and high adsorption capacity.(4)In the past ten years,there have been many studies on MOF both computationally and experimentally.However,there are few systematic calculation studies on IL/MOF composites.The main reason is that the IL/MOF composites need to be constructed by molecular dynamics(MD)method in the traditional calculation.The process is cumbersome and complicated,and it is difficult to carry out large-scale calculation and analysis.In the guidance of Material Genomics,we assembled 330,991 MOF materials by using our crystal assembly program,and developed a high-throughput IL/MOF constrcuction method based on the configuration-based Monte Carlo(CBMC)method.By comparing the CBMC method with the MD method and experimental data,the feasibility of the CBMC method is fully proved,and the high-throughput assembly of the IL/MOF composites is successfully realized.(5)Large-scale screening of IL/MOFs by high-throughput molecular simulation was performed to explore the performance of IL/MOFs on CO2/CH4 separation.Through analysis,it is found that ILs are strictly confined as cation and anion alternating nano wires in MOFs with columnar pores of about 9 A,which constitutes a synergistic adsorption site of the "core-tube" structure.The formation of this site can simultaneously increase the amount of adsorption capacity,selectivity,and working capacity of the materials.Therefore,we propose the concept of synergistic adsorption sites and propose novel ideas and concepts for composite materials design.