Study And Application Of Ni-based Catalyst In The Catalytic Hydrodechlorination Of Chlorobenzene

Catalytic hydrodechlorination（HDC）is an efficient,economical and environmental friendly method for treating chlorinated organic pollutants.Supported catalysts are often used,and nickel-based catalysts are widely used in catalytic hydrodechlorination reactions because of their low cost and good hydrodechlorination performance.This paper systematically studies the hydrogenation of chlorobenzene under different nickel-based catalysts to clarify the structure-activity relationship between the catalysts’structural characteristics and their catalytic efficiency.The specific research content is as follows:Using silica as a carrier,we prepared a nickel-based catalyst by impregnation and the gas-phase HDC of chlorobenzene was conducted in a down-flow glass reactor with a quartz frit at certain temperature under atmospheric pressure.After the nickel-based catalyst Ni/SiO₂ was prepared,the catalyst Ni/SiO₂ was modified,with different contents of tetraethyl orthosilicate（TEOS）to forming a shell on the catalyst surface,and cetyltrimethyl Ammonium bromide（CTAB）was further added and used to adjust the pore structure of the shell.The successful preparation of the catalyst was confirmed by XRD,TEM,XPS,TPR and other characterization methods,and the activities of different catalysts were also tested.In the process of chlorobenzene-catalyzed hydrogenation,the core-shell structure catalyst Ni/SiO₂@SiO₂ showed better stability and activity than the Ni/SiO₂.The initial activity of Ni/SiO₂ was 73.35%.After catalytic hydrodechlorination of chlorobenzene for10 hours,the catalyst activity became 51.89%.By comparing the catalytic hydrogenation effect of each catalyst,it was determined that the optimal catalytic effect was a Ni/SiO₂@SiO₂-0.125 catalyst obtained when TEOS was added in an amount of 0.125 ml.After 10 hours of catalytic hydrodechlorination of chlorobenzene,the catalyst activity decreased from 93.09%to 82.38%.It is shown that the Ni/SiO₂@SiO₂ core-shell catalyst prepared by improved stober method possess high dispersibility and good stability,and it can effectively reduce the loss of active components of the catalyst during the hydrodechlorination reaction and suppress the loss of catalyst.This phenomenon provides a reasonable basis for studying the stability and activity of hydrodechlorination catalysts.