Impregnation Synthesized Cu@MIL‐101(Cr) Catalyzes the Oxidation of Styrene to Benzaldehyde with TBHP**

Abstract A series of M@MIL‐101(Cr) (M=Cu, Co, Ni and Mn) adopting impregnation method were fabricated as heterogeneous catalysts to oxidize styrene to benzaldehyde with tert‐butyl hydroperoxide (TBHP). The morphology of the MIL‐101(Cr) was nicely retained after the uniform dispersion of metals. In order to obtain the optimized reaction conditions, various in‐depth investigations were carried out to evaluate the effects of reaction time and reaction temperature on catalytic efficiency. Importantly, the Cu@MIL‐101(Cr) performed best in this study, the highest styrene conversion and the benzaldehyde selectivity can reach 97.45 % and 84.39 %, respectively, which revealed the synergetic effects of Cu 2+ and Cr 3+ in Cu@MIL‐101(Cr) on the styrene oxidation. Furthermore, the result of a three‐cycle experiment demonstrated the good recyclability of Cu@MIL‐101(Cr) without considerable structural deterioration and loss in activation. A possible mechanism of oxidation of styrene by using Cu@MIL‐101(Cr) and TBHP was also proposed.