Computational Screening And Design Of New Nanoporous Materials For Energy Gas Separation

At present,metal-organic frameworks(MOFs)and covalent organic frameworks(COFs),as new nanoporous materials,have shown outstanding capabilities in many fields,especially in gas separation due to their unique structural characteristics.This brings new hope for the purification of natural gas.In this paper,through large-scale computational screening and design based on molecular simulation methods,a systematic study on the adsorption separation and membrane separation of MOFs and COFs for energy gas was conducted:(1)The performance of 5,109 CoRE MOF materials in CH4/N2 separation was evaluated by high throughput computational screening method.Through the analysis of structure-activity relationship,it is found that MOFs with one-dimensional channels,PLD in the range of 3.8?4.7 A and LCD in the range of 4.2-5.4 A have high CH4/N2 separation performance.Based on the study of structure-activity relationship and adsorbility(AD),the material design strategies based on structure and energy were proposed.Finally,five candidate materials were selected from 303,991 virtual MOFs,and their separation selectivity exceeded the highest value reported in experiment.The important influence of multiple van der Waals interactions on CH4/N2 separation was determined.This provides a theoretical basis for the design of MOFs to improve the separation performance.(2)The latest COFs were collected,and the number of the database of the CoRE COF materials was updated to 309.At the same time,the calculation reliability of molecular simulation on the separation of gas by pure membrane and composite membranes was evaluated.Furthermore,the performance of the COF@Ploymer mixed matrix membranes(MMMs)on CH4/N2 separation was evaluated by using the CoRE COFs as the filler and three kinds of polymers as matrix.Finally,DCOF-1 with excellent performance was successfully designed with the design strategy of LCD in the range of 4?5 A,PLD/LCD ratio equal to 0.9 and the two-dimensional material with the channel as the tubular shape,which provided directions for the efficient application of COF membranes.(3)298 COFs were selected from the database of the CoRE COF metarials to explore the structure-property relationships of the separation of CO2/CH4 by the COF membranes.12 COFs with excellent performance characteristics were classified as:type ?(structure with extremely small pores);type ?(2D-COFs in staggered stacking modes and 3D-COFs with interpenetrating configurations);type ?(COF structures with CO2 favorable interaction sites).According to the characteristics of type III COFs,the 11 COFs were modified by 10 functional groups,and the positive effects of-F and-Cl functional groups on the membrane properties were confirmed by molecular simulation.Furthermore,it is confirmed that the MMMs with these good designed COF materials as fillers has the same excellent performance in CO2/CH4 separation.This provides a reasonable guide for the design of new-type COF membranes and the selection of ideal COFs fillers for polymer MMMs.