Highly efficient aerobic oxidation of tetralin to α-tetralone over MnOx–CoOy/γ-Al2O3 catalysts

A series of (aMnOx–CoOy)r/γ-Al2O3 catalysts with different molar ratio of metal and supports (r denotes as the molar ratio of metal and supports, r = 0.02,0.03,0.04,0.05,0.06,0.08) and varied metal molar ratio(a stands for the molar ratio of Mn:Co, r = 1/3,1/1,3/1,6/1,1/0) were fabricated through impregnation route and characterized using X-ray diffraction (XRD), Inductively coupled plasma-atomic emission spectrometry (ICP-AES), N2 adsorption–desorption, X-ray photoelectron spectroscopy (XPS), H2 temperature programmed reduction (H2-TPR) and Scanning emission microscope (SEM). Among the catalysts investigated, (3MnOx–CoOy)0.04/γ-Al2O3 exhibited the highest activity and stable recyclability in the selective oxidation of tetralin using oxygen as the oxidant with a tetralin conversion of 68% and α-tetralone selectivity of 75% under the optimized conditions, affording a TOF value of 6.53 h−1, where the optimal reaction temperature is 120 °C and the reaction time is 8 h.