Vanadium-zirconium Catalyst For Aerobic Oxidation Of Benzene To Phenol

Phenol is an important organic chemical intermediates.It has important application value in industry,agriculture,medicine,spice,dyes and so on.The90%phenol is prepared by isopropylbenzene process.However,there are many disadvantages,such as long technological process,low atomic utilization rate,excess coupling products and so on.Therefore,compared with the traditional preparation method,the advantages of one-step hydroxylation benzene to phenol are obvious.Not only the byproducts are not harmful to the environment and the reaction process is less than traditional method,but also the phenol is not affected by the price fluctuation of linked products,which is consistent with the green concept of sustainable development.So,the green process of one-step prepared benzene to phenol has been paid lot attention.In this paper,phenol was prepared by direct hydroxylation of benzene with oxygen as oxidant.In this paper,a series of catalysts were synthesized with vanadium as active center and zirconium as the synergistic reaction.The reaction activity of the catalyst was investigated.The amount of catalyst,solvent,the capacity of loading,reaction time,reaction temperature and other factors on the final results of the reaction.The main contents of the study are as follow:With V-Zr compound as the active canter of the reaction,a series of different supports catalysts were prepared under the same conditions,such as V-Zr/AC,V-Zr/MWCNTs,V-Zr/Bent,V-Zr/C₃N₄,V-Zr/?-Al₂O₃.And the catalyst activity of hydroxylation benzene to phenol was investigated.Meanwhile,the reaction kinetic and recycle effect of the catalyst V-Zr/AC was observed.The effects of different supports on the activity of the catalyst and selectivity of phenol were also analyzed and explored by the XRD,XPS,TEM,SEM,Raman and so on.And the reaction process was optimized.The optimized reaction conditions were as follows:150 mg V-Zr/AC catalyst,3.0 mL acetonitrile,20%loading capacity of V-Zr in active center,0.7 g ascorbic acid,3.0 MPa O₂,80?reaction temperature for 5 h.The maximum yield of phenol could reach 8.7%.A series of V/Ui O-66-NH₂ catalysts with different loading capacity were prerared by immobilization of VO?acac?₂ on UiO-66-NH₂ organometallic framework.In order to improve the recycle efficiency of the catalyst,the catalyst was calcined at different temperature,and the catalysts of different calcined temperature were obtained,such as V/Zr O₂-500,V/ZrO₂-600,V/ZrO₂-700,V/ZrO₂-800,and the reaction activity of hydroxylation benzene to phenol of catalyst was also investigated.Then the catalytic mechanism of the catalyst V/Ui O-6-NH₂ was discussed,which hydrogen isotopic effect of the catalyst was studied.The optimum reaction conditions were as follow:1.0 mL benzene,3 mL70 vol.%acetic acid solvent,50 mg catalyst V/UiO-66-NH₂,3.0 MPa O₂,60?reaction temperature for 21 h.The maximum yield of phenol could reach to 22.0%and phenol selectivity was also get 99.0%.It is superior to most catalysts for oxidation of benzene to phenol by oxygen.