Introducing π-electron-rich aromatic rings into a robust Zr-MOF for efficient natural gas purification and C3H8/n-C4H10 recovery†
Abstract
The natural gas upgrading applications involving CH4 purification and concurrent C3H8/n-C4H10 recovery are of great importance yet highly challenging for safe and efficient subsequent manufacturing of downstream commodities due to their similar physicochemical properties and ultra-low concentration. Herein, a robust Zr-MOF, LIFM-233, with optimized pore size/volume/surface ascribed to the introduction of π-electron-rich naphthalene moieties, has been constructed with 6-(4-carboxyphenyl)-2-naphthalenecarboxylate (L) and Zr6 cluster for natural gas upgrading. Based on the high pore volume, optimized pore size, and π-electron-rich pore surface, LIFM-233 presents high C3H8/n-C4H10 uptake capacity (229.3/262.8 cm3 g−1 at 298 K and 1 bar) and good C2–C4/CH4 selective adsorption performance, confirmed by single-component adsorption and dynamic breakthrough experiments. Additionally, high purity of C3H8 (>91.6%) or n-C4H10 (>94.0%) can be afforded through a single regeneration curve. The underlying gas-binding mechanism has been well established by theoretical simulations, which reveal that C–H⋯O hydrogen bonds (HBs) between gas and Zr–O clusters, and C–H⋯π interactions between gas and aromatic rings, collaboratively play pivotal roles in the selective separation of C2–C4 hydrocarbons from CH4, thus demonstrating the importance of the introduction of an appropriate aromatic system.