Structural Design Of Covalent Organic Framework Materials

Carbon dioxide emission resulting from traditional fossil fuels such as coal,oil burning.Carbon dioxide emissions contribute to global warming.How to absorb carbon dioxide to be a problem.At the same time due to the continuous increase of the price of traditional energy consumption and to seek new alternative to traditional energy sources of pollution,clean and efficient alternative energy become one of the current problems need to be resolved.Methane has become one of the most promising energy sources in the future because of its large reserves,high hydrogen and carbon ratios and sufficient combustion products to produce only a small amount of CO2,which is attracting more and more attention.The biggest problem in the practical application of methane is the safe and efficient storage and transportation.As the porous material has a large specific surface area,the advantage of small density is a perfect adsorbent for adsorbing methane,carbon dioxide and other gases.Recently a new class of porous materials covalent organic frameworks are designed and synthesized.COF is a crystalline porous material formed by strong covalent bonds C-N,C-B,C-Si,B-O,etc.,which are composed of elements such as light element C,N,O,B and Si,which are completely connected by organic link units.COF has the potential to be used in the storage,separation and catalysis of gas because of its advantages such as large specific surface area,low density,adjustable pore size and high thermal stability.Experiments have synthesized many COF materials and characterized the adsorption properties of gas.However,due to the diversity of materials and the complexity of pore structure,it is difficult to study them by means of experimental method.Since the development of molecular simulation technology,we can use molecular modeling techniques to explain the experimental problem,predicted COF structure and properties.In this paper,two kinds of COF materials were designed by molecular simulation technique,and the adsorption performance of methane was simulated by Monte Carlo simulation method.The main contents are as follows:Briefly introduces the covalent organic framework and its structural design,adsorption performance and research status.And elaborated the research basis and research content of this paper.Briefly introduces the computational methods includes quantum mechanics,molecular mechanics,Monte Carlo,quantum mechanics-molecular mechanics,and software;In order to broaden the type of COF,a series of new COF materials formed by C-O,N-N,B-N covalent bond design with organic link unit with different symmetries.The properties of the surface area,free volume,porosity and methane adsorption properties of each COF material were simulated by molecular simulation method.And reveals the relationship between structure and properties;In order to improve the gas adsorption performance,two new 3D-COF materials were designed based on the COF-102 structure.Based on the topology of COF-102,a series of new COF materials were designed by increasing the heteroatom nitrogen and alkynyl groups.The Monte Carlo method was used to simulate the adsorption properties of methane molecules and newly designed 3D-COF at 298K1-60bar.