Computational Study On Metal-Organic Frameworks And Covalent—Organic Frameworks For Removal Of H₂S From Natural Gas

Metal-Organic Frameworks (MOFs) is a kind of nanoporous material similar to zeolites. This type of material has the peculiarities of structural divercity, high specific surface area and high porosity. Covalent-Organic Frameworks (COFs) is another kind of nanoporous material similar to zeolites which has the advantage of less density than MOFs. Based on these superiorities, these two kinds of materials have received widely attention and shown potential application in many fields such as gas separation, gas storage, pharmaceutical carrier and so on. Compared with traditional fossil energy, natural gas has higher utilization efficiency, less combustion process pollution, and has become an increasing demand alternative energy. In addition to the main component CH4, there are H2S and other harmful substances in natural gas. H2S would corrode its transportation and storage devices, leading to environmental pollution and harmful to our health. It is necessary to separate H2S from natural gas effectively and finding suitable H2S adsorbent in order to reduce the harm. MOFs and COFs are two kinds of potential adsorbents, as a result, the grand canonical Monte Carlo (GCMC) method was adopted to study these two types of materials. Introducing computational chemistry into the screening of adsorption and separation performance of materials has broken the limitations of the traditional experimental characterization method, it can not only reduce the screening time but also can save the resources and provide theoretical basis to design new materials with good adsorption and separation performance.In this paper, we choose 33 water stable MOFs and 28 COFs for the calculation and selection of H2S selectivity and working capacity, and calculate the influence of different contents of H2O on the separation properties of the materials were also investigated.The main contents are as follows:1. The separation of H2S/CH4 mixture was studied under 303 K and the pressure range 0.01 MPa to 1 MPa for the MOFs and COFs. The materials with high selectivity were screened out and their features were analyzed, providing theoretical guidance for the design new materials with good performance.2. The working capacities of the MOFs and COFs in Pressure Swing Adsorption and Vacuum Pressure Swing Adsorption processes were calculated. Furthermore, the materials with high working capacity were screened out and their features were summarized.3. The selectivity and working capacity of the MOFs and COFs were compared. We found that for both selectivity and working capacity, the COFs are slightly better than the MOFs, providing useful information for finding good adsorbents in future.4. The effect of water on the selectivity and working capacity of the MOFs and COFs were further studied.