Continuous and Large-Scale Preparation of Hierarchical Porous HKUST-1 via the “Nanofusion” Mechanism Using Liquid-Assisted Mechanosynthesis

Abstract

Hierarchical porous metal–organic frameworks (HP-MOFs) have attracted considerable attention because of their hierarchical pores, which can address the slow mass transfer and less exposure of active sites in pristine microporous MOFs. Although several preparation methods have been developed to date, a large-scale technique for the synthesis of HP-MOFs is still lacking. In this study, we report a novel method for the large-scale synthesis of HP-HKUST-1 based on liquid-assisted spiral gas–solid two-phase flow (LA-S-GSF). This method ingeniously uses a nebulizer to promote the rapid synthesis of nano-HKUST-1 by introducing trace amounts of water during the S-GSF reaction. During the washing and drying process, these nanoparticles were fully fused to form nanocrystalline aggregates, resulting in a hierarchical porous structure with a large number of micropores, mesopores, and macropores. The pore size distribution can be regulated by changing the drying temperature to obtain HP products with combinations of micropores and mesopores, micropores and macropores, and the formation mechanism of the HP structure was also explored. This method required only 11 min of reaction time to obtain 25.2 g of HP-HKUST-1 in 96% yield, with a corresponding space-time yield (STY) of 6.9 × 10⁴ kg m^–3 day^–1.