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.