Study Of Zinc Acetate/activated Carbon Catalyst For Vinyl Acetate Synthesis From Acetylene

In order to improve the activity of catalyst for vinyl acetate synthesis,this paper firstly aims at contributing to the further understanding of the role of carbon oxygen surface groups on the properties of the carbons themselves and of the carbon-supported zinc acetate catalysts prepared by impregnation.Based on the above conclusion,a proper treatment was selected to modify the activated carbon supports.Our work mainly focuses on studying tile effects of surface texture and surface chemistry,modification and raw materials of supports and metal ion CO-catalysts,and remarkable progresses have been achieved and are summarized as follows:(1)The heat treatment was selected firstly to study the effect of carbon oxygen surface groups on the catalytic activity,and the reaction mechanism was brought forward.The C=0 groups,which were present in carbonyls,lactones,carboxylic anhydrides and carboxyls,participate in the conjugate system of carbon suppots. Zinc acetate links up with C=O groups.The conj ugate system makes the electron transfer between acetylene and zinc acetate more easily.Thus,the above four surface oxygen groups play a positive role in the catalytic activity.However,Phenol can not coordinate to zinc acetate,due to the disturbance of hydrogen.And the strong intermolecular hydrogen bonds can be easily between phenols and C=O groups.As a result,phenols in the vicinity of C=O groups may hinder the coordination between C=O groups and zinc acetate or even prevent such coordination,due to steric hindrance.Thus,phenols play a negative role.Activated carbon not only plays a role of carrier,but also is a kind of co—catalyst.(2)In order to improve the activity of catalyst for vinyl acetate synthesis, activated carbon suppo^s were modified by oxidation in the gas phase.The surface texture of supports,which were oxidized in the gas phase with 5%O₂,changed unnoticeably,the surface chemistry changed noticeably;however,both surface texture and surface chemistry of supports were changed by oxidation in air.The optimal arrangement of surface oxygen groups was obtained by oxidation in 5%O₂ at 698K for 4h,and the corresponding catalytic activity was increased by 1 1.45%; the surface area and macro and mesopore surface alea were increased noticeably,...