Co-M/Al2O3上环己烷的选择性氧化研究

采用溶胶-凝胶法制备了Co-M/Al₂O₃(M=Cu，Zn，Ni)催化剂。在没有任何有机溶剂或助剂的条件下，研究了以空气为氧化剂的环己烷选择性氧化。所制备四种催化剂的活性为Co-Ni/Al₂O₃ >Co/Al₂O₃ >Co-Zn/Al₂O₃ >Co-Cu/Al₂O₃。在Co-Ni/Al₂O₃中Co、Ni的质量分数分别为4.0%和3.0%时活性最好。以Co-Ni/Al₂O₃为催化剂，在4.5 MPa、443 K下反应120 min，环己烷转化率达9.9%，环己酮和环己醇的总选择性达94.6%，n(酮)∶n(醇)为2.8。Co-Ni/Al₂O₃催化剂连续使用五次后活性基本不变。

Selective oxidation of cyclohexane over Co-M/Al2O3 catalyst

Selective oxidation of cyclohexane to cyclohexanol and cyclohexanone with air was investigated over Co/Al_2O_3 and Co-M/Al_2O_3 (M=Cu, Zn and Ni) catalysts prepared by sol-gel method, without assistance of any organic solvent or activator. Activity of the catalysts declines in the following order: Co-Ni/Al_2O_3 >Co/Al_2O_3 >Co-Zn/Al_2O_3 >Co-Cu/Al_2O_3. Optimum activity was attained at cobalt and nickel loading of 4.0 wt% and 3.0 wt%, respectively, in Co-Ni/Al_2O_3 catalyst. Cyclohexane conversion of 9.9%, selectivity to cyclohexanone and cyclohexanol of 94.6% and cyclohexanone-to-cyclohexanol ratio of 2.8 were obtained over the Co-Ni/Al_2O_3 catalyst at 443 K, 4.5 MPa and reaction time of 120 min. Activity of the catalyst remained unchanged after five times of repeated use.