Phenol is a kind of important chemical materials, which is mainly produced from isopropylbenzene oxidation process. The drawbacks of the process include long synthesis process, consuming propylene and forming byproducts. Directly oxidation of benzene to phenol with molecular oxygen, possessing the advantages of less steps, low cost and environmental friendly, has become the research hotspot in green preparation of phenol. In this review, the progress of oxidation of liquid benzene to phenol with oxygen is summarized systematically. The reaction system, including the reaction mechanism, catalysts, and reductant is reviewed. The effects of reaction temperature, oxygen pressure, reductant and solvent on the yields of phenol are also discussed. Furthermore, the current research problems and future research perspectives are also suggested.

Contents
1 Introduction
2 Reaction mechanism
3 Catalysts
3.1 Vanadium-based catalysts
3.2 Copper-based catalysts
3.3 Heteropolyacids-based catalysts
3.4 Other catalysts
4 Reductants
5 The effects of reaction conditions
5.1 Reaction temperature
5.2 Reaction pressure
5.3 The account of reductant
5.4 Solvents
6 Conclusion and outlook