High‐Capacity Volumetric Methane Storage in Hyper‐Cross‐Linked Porous Polymers via Flexibility Engineering of Building Units
Jiarui Hu, Hui Gao, Xiaoyan Wang, Bien Tan
Abstract
Abstract Adsorbed natural gas (ANG) storage is emerging as a promising alternative to traditional compressed and liquefied storage methods. However, its onboard application is restricted by low volumetric methane storage capacity. Flexible porous adsorbents offer a potential solution, as their dense structures and unique gate‐opening effects are well‐suited to enhance volumetric capacity under high pressures. This study developes a series of hyper‐cross‐linked polymers (HCPs) with tunable flexibility by modifying the aliphatic chain length in double‐benzene‐ring building blocks, employing a cost‐effective external crosslinking approach. The resulting flexible polymer, HCP‐DPP, exhibits pore expansion under specific methane pressures, producing a high‐pressure adsorption isotherm with gate‐opening behavior. Combined with its intrinsic dense skeleton, this feature leads to superior volumetric methane storage performance over rigid counterparts. Notably, HCP‐DPP achieves a record‐high volumetric total uptake of 333 cm 3 STP cm −3 and a working capacity of 291 cm 3 STP cm −3 at 273 K and 100 bar, exceeding the U.S. Department of Energy (DOE) target of 263 cm 3 STP cm −3 . These findings lay a foundation for developing advanced flexible porous adsorbents for practical ANG applications.