High-throughput screening of metal–organic frameworks for hydrogen purification

Abstract

In industry, the separation/purification of hydrogen from methane impurity is of significant importance, especially under the background of carbon dioxide mitigation towards carbon neutrality. Adsorption separation is an effective route for this application regarding energy cost and separation efficiency, for which the selection of adsorbents is the key. This work proposes a computer-aided high-throughput screening strategy for the selection of metal–organic frameworks (MOFs) for CH4/H2 separation, striving to accelerate the practice of discovering better adsorbents for this particular application. Firstly, a prescreening was conducted on 12,020 computation-ready three-dimensional MOFs based on intuitive structure and chemical analysis, shortlisting 5,096 candidates. Secondly, a molecular simulation-assisted structure–property relationship analysis was performed based on small sampled MOFs, from which two structure criteria were derived for high-performing MOFs. Based on the criteria, a screening procedure was then carried out, narrowing the candidate MOFs down to 2,408. The rigorous molecular simulation was again applied to assess the separation performance metrics of these MOFs, covering adsorption selectivity, working capacity, adsorbent performance score, regenerability and separation potential. By analysing the simulated performance indicators, top-performing MOFs were identified and a more detailed analysis of the structure-performance relationship was carried out. Additionally, the impact of several practical factors, covering humidity, operation temperature and inlet gas composition, on the performance of the selected adsorbents in practice was explored. It was observed that the robustness of MOFs at humidity depends on their hydrophilicity and preferential adsorption sites. Meanwhile, operation temperature can be manipulated to accommodate flexible production scenarios.