The research progress of catalysts for oxidation of cyclohexane to cyclohexanone by molecular oxygen is reviewed. The application of photocatalyst, nano-catalyst, bionic catalyst, molecular sieve catalyst and composite catalyst in catalytic oxidation of cyclohexane was emphatically introduced. Among them, the nano-gold catalyst supported by molecular sieve has high catalytic activity, selectivity and stability.

Key words: cyclohexane oxidation, cyclohexanone, understanding catalyst.

Cyclohexanone is an important organic chemical raw material and industrial solvent, which is widely used in medicine, paint, coating, rubber, pesticide industry, printing and plastic recycling. At present, the main industrial methods for preparing cyclohexanol and cyclohexanone are phenol hydrogenation, benzene partial hydrogenation and cyclohexane liquid phase oxidation, among which cyclohexane oxidation is the most widely used, accounting for more than 90%.

Because cyclohexanol and cyclohexanone are easier to be oxidized than cyclohexane, in order to obtain suitable selectivity of cyclohexanol and cyclohexanone, the industrial oxidation conversion rate of cyclohexane is usually controlled at 3.5%~5.0%, and the oxidation selectivity is about 90%.

However, the massive circulation of cyclohexane has caused huge energy consumption and waste. At present, the research focus of cyclohexane oxidation process mainly focuses on the transformation and optimization of traditional process, the selection of oxidant and the development of efficient catalyst. Developing high-performance and environment-friendly catalysts has become a research hotspot. Some oxidation catalysts developed in recent years have shown good performance in improving cyclohexane conversion and product selectivity.

In this paper, the research progress of catalysts for oxidation of cyclohexane to cyclohexanone by molecular oxygen is reviewed.