Ambidextrous fine-tuning of zeolite-like hydrogen-bonded organic frameworks (HOFs) via scalable green synthesis for efficient biogas upgrading

Abstract

Zeolite-like supramolecular assemblies (ZSAs) are a distinctive class of hydrogen-bonded organic frameworks (HOFs) that form zeolite-like structures using fundamental four-membered ring (4 MR) building units, known as metal–organic squares (MOSs). Herein, we developed a zeolite-like supramolecular assembly (ZSA) platform to precisely control hydrogen-bond directionality, coupled with confinement effects, ultimately synthesizing two isoreticular HOFs, ZSA-12 and ZSA-13, with distinct pore environments. Notably, owing to their microporous structures, ZSA-12 and ZSA-13 exhibited exceptional CO₂ adsorption capacity and ultra-high CO₂/CH₄ separation selectivity. The IAST selectivity value of 94.8 sets a benchmark, surpassing that of all previously reported HOFs. Theoretical calculations and breakthrough experiments confirmed the outstanding separation capability of ZSA-12 and ZSA-13, both of which also demonstrated remarkable thermal and chemical stability. Furthermore, gram-scale synthesis of ZSA-12 and ZSA-13 was successfully achieved under mild conditions using pure water as the solvent—one of the few reported HOFs that can be synthesized in large quantities via a water-based process at an exceptionally low cost. Thus, ZSA-12 and ZSA-13 offer a new strategy for the synthesis of isoreticular HOFs and hold great promise for biogas purification and upgrading applications.