A novel water-stable MOF Zn(Py)(Atz) as heterogeneous catalyst for chemical conversion of CO₂ with various epoxides under mild conditions

A novel Zn-based three-dimensional framework Zn₂(Py)(Atz)₂·DMF·2H₂O (H₂Py = 3,5-Pyridinedicarboxylic acid, Hatz = 3-Amino-1,2,4-triazole) abbreviated as Zn(Py)(Atz), with micropores and outstanding stability, was facilely fabricated by employing mixed ligands of nitro-rich unit amitrole and 3,5-dipicolinic acid. The Zn site acted as Lewis acid for epoxides activation, abundant micropores (BET surface area 764.5m²/g, pore volume 0.32cm³/g) and nitro-rich unit facilitated CO₂ sorption and its activation. The acid-base synergistic effects of Zn(Py)(Atz) MOF catalyst resulted in its promising potential in CO₂ chemical conversion. Satisfactorily, Zn(Py)(Atz) exhibited decent CO₂ sorption capacity (52.3 cm³/g at 273 K) and good performance of 92.1% propylene carbonate yield and 98% selectivity for the CO₂ cycloaddition to propylene oxide under mild conditions (60 °C 1.5 MPa), also high cyclic carbonates yields and selectivities were obtained over various epoxides. Moreover, PXRD analysis confirmed the excellent stability of Zn(Py)(Atz) in distilled water (>1 week) and acid/or base aqueous solution (pH = 2-14 for 72 h), which could meet the demand of industrial environment. Additionally, the Zn(Py)(Atz) catalyst was completely recycled for seven times with little decrease in product yield. The efficient, highly stable, easily recycle and solvent-free catalyst reported herein is potential material in CO₂ capture and utilization.