Sustainable supercritical-mechanochemical process

Mechanochemistry offers a route for converting metal oxides directly into metal organic frameworks (MOFs), ensuring maximal atomic utilization. Here, we have advanced reaction scope to the supercritical regime for establishing an integrated quasi-continuous synthesis, separation, and activation process (supercritical-mechanochemical process, SCM). Within SCM, supercritical CO₂ (SC CO₂) facilitates a spatiotemporally uniform distribution of substoichiometric cosolvent (η < 0.2 μL·mg-¹) across mechanochemical hot-spots, where its near-zero interfacial tension optimizes mass transfer efficiency and accelerates grinding-induced nucleation. The circulation of SC CO₂-cosolvent enhanced the ability of metastable phases to form specific topological frameworks, either through monomer-crystalline interactions or intermediate transitions. A pilot-scale facility verified a rapid production rate from an initial input of 3.5 kg to the final product within 8-hour process cycle (space-time yield of 544.29 kg·m^-3·d^-1), along with ligand and cosolvent recovery rates reaching 42.66 wt% and 89.48 wt%, respectively. Techno-economic assessment underscored substantial cost advantages over conventional solvent-based methods, positioning SCM as a sustainable and competitive approach for scalable production.