Hydrotalcite-derived Co-MgAlO mixed metal oxides as efficient and stable catalyst for the solvent-free selective oxidation of cyclohexane with molecular oxygen

Abstract

Developing a highly efficient and stable catalyst for the selective aerobic oxidation of saturated hydrocarbons to functional compounds is highly desirable in chemical industry. In our present work, hydrotalcite-derived Co-MgAlO mixed metal oxides as efficient and stable heterogeneous catalyst for the selective aerobic oxidation of cyclohexane to KA-oil has been developed. The results indicate that hydrotalcite-derived Co-MgAlO mixed metal oxides catalysts are active and selective; the synergistic catalysis of Co3+ and Co2+ can effectively promote the decomposition of cyclohexyl hydroperoxide (CHHP) intermediate to KA-oil. 9.1% of cyclohexane conversion and 82.0% of KA-oil selectivity over 2%Co-MgAlO catalyst with high turnover numbers (3800) was obtained at 423 K and 0.6 MPa for 2 h in this oxidation reaction. Moreover, the hydrotalcite-derived Co-MgAlO catalyst is easy to be separated and recycled, and its catalytic performance was still stable after five runs. The schematic reaction pathway for the oxidation of cyclohexane to KA-oil over Co-MgAlO mixed metal oxides catalyst was also suggested. Maybe this work employing inexpensive hydrotalcite-derived Co-MgAlO as highly efficient and environmentally friendly catalyst for the preparation of KA-oil has potential industrial application prospects.