ZIF-67 with precursor concentration-dependence morphology for aerobic oxidation of toluene

Designing high-efficiency catalyst for the oxidation of toluene (TOL) into value-added products like benzyl alcohol, benzaldehyde and benzoic acid is of great significance in chemical industry. Herein, four type of ZIF-67 with different morphology (ZIF-67-6, ZIF-67-12, ZIF-67-18, and ZIF-67-24) are prepared by tuning the concentration of precursor. About 90% of TOL conversion is obtained in the presence of ZIF-67-24 (0.1–0.2 μm, polyhedrons) by using O2 (>99.9%, 1 atm) as oxidant at 40 °C after 4 h of reaction. Excellent performance of ZIF-67-24 could be attributed to two reasons: (I) The good crystallinity and smaller size with larger BET surface (2037 m2 g−1). (II) The electron deficient Co in ZIF-67-24 may be responded to the fast initiation of radical chain process of TOL oxidation. The research may provide a promising concept for oxidation of C-H under mild condition.