Direct Hydroxylation of Benzene to Phenol over TS-1 Catalysts

Yuecheng Luo,Jiahui Xiong,Conglin Pang,Guiying Li,Changwei Hu

doi:10.3390/catal8020049

Abstract

We synthesized a TS-1 catalyst to directly hydroxylate benzene to phenol with H2O2 as oxidant and water as solvent. The samples were characterized by FT-IR (Fourier Transform Infrared), DR UV-Vis (Diffused Reflectance Ultraviolet Visible), XRD (X-ray diffraction), SEM(scanning electron microscope), TEM (Transmission Electron Microscope), XPS (X-ray photoelectron spectroscopy), ICP (inductively coupled plasma spectrum), and N2 adsorption-desorption. A desirable phenol yield of 39% with 72% selectivity was obtained under optimized conditions: 0.15 g (0.34 to the mass of benzene) TS-1, 5.6 mmol C6H6, reaction time 45 min, 0.80 mL H2O2 (30%), 40.0 mL H2O, and reaction temperature 70 °C. The reuse of the TS-1 catalyst illustrated that the catalyst had a slight loss of activity resulting from slight Ti leaching from the first run and then kept stable. Almost all of the Ti species added in the preparation were successfully incorporated into the TS-1 framework, which were responsible for the good catalytic activity. Extraframework Ti species were not selective for hydroxylation.

Highlights

Phenol is an important chemical widely used in medicine, pesticides, plastics, and so on.The cumene method is the main process for phenol production in current commercial manufacturing, and this method has three steps from benzene to the target product [1,2,3]
The yield of phenol was 17% and the selectivity of phenol was 75% over the commercial TS-1, whereas the yield of phenol over S-1 was low, less than 1%
The TS-1 catalyst was prepared by a hydrothermal synthesis method which was similar to that in our previous work [32]

Summary

Introduction

Phenol is an important chemical widely used in medicine, pesticides, plastics, and so on. The cumene method is the main process for phenol production in current commercial manufacturing, and this method has three steps from benzene to the target product [1,2,3]. The yield of phenol is not high, with disadvantages of high energy consumption and equipment corrosion. The number of studies on the synthesis of phenol directly from benzene has been increasing, emphasizing environmental friendliness and economic feasibility. The one-step direct hydroxylation of benzene to phenol with hydrogen peroxide, which requires the activation of C–H bonds in the aromatic ring and the subsequent insertion of oxygen, has drawn much attention [6,7,8,9]. Several efficient catalysts with high activity and stability have been designed and tested [10,11,12,13]

Methods

Results

Conclusion