Quantitative structure–property relationships from experiments for CH₄ storage and delivery by metal–organic frameworks

Quantitative structure–property relationships (QSPRs) can be applied to metal–organic frameworks (MOFs) to allow for reasonable estimates to be made of the CH₄ storage performance. QSPRs are available for CH₄ storage of MOFs, but these were obtained from Grand Canonical Monte Carlo (GCMC) simulations which have come under scrutiny and of which the accuracy has been questioned. Here, QSPRs were developed from experimental data and insights are provided on how to improve storage and deliverable CH₄ storage capacity based on material properties. Physical properties of MOFs, such as density, pore volume, and largest cavity diameter (LCD), and their significance for CH₄ storage capacity were assessed. One relationship that was found is that CH₄ gravimetric storage capacity is directly proportional to Brunauer–Emmett–Teller (BET) surface area (r² > 90%). The QSPRs demonstrated the effect of van der Waals forces involved in CH₄ adsorption. An assessment was made of the accuracy of QSPRs made by GCMC as compared to QSPRs derived from experimental data. Guidelines are provided for optimal design of MOFs, including density and pore volume. With the recent achievement of the gravimetric 2012 DOE CH₄ storage target, the QSPRs presented here may allow for the prediction of structural descriptors for CH₄ storage capacity and delivery.