Preparation Of Supported Ni/TiO₂-SiO₂ Catalyst And Its Catalytic Effect On Turpentine Hydrogenatio

Pinane is an major industrial material for the perfume and pharmaceutical industry.It is an important intermediate for the synthesis of linalool,citronellol,musk rose,dihydromyrcenol and so many valuable fragrance compounds.It widely used for the production of perfumes.Pinane exist two kinds of cis and trans isomers,the activity of cis-pinane is considerably higher than that of trans-pinane,so the cis-pinane is primarily demand for industrial manufacture.Cis-pinane can be obtained by the hydrogenation of α-pinene which contains a lot in turpentine.China is a country that produces a great deal of turpentine and thus it is an important task to produce cis-pinane by the catalytic hydrogenation of α-pinene.In order to overcome a series of shortcomings of the precious metal catalyst,such as expensive,difficult to separate and reuse,and so on.In this work,nickel catalysts were prepared by the sol-gel method and applied α-pinene catalytic hydrogenation.The structures and properties of the catalysts were characterized by different techniques,and correlated to the catalytic activity.The following several aspects were researched:(1)The supported Ni/TiO2-SiO2 catalysts were prepared by the sol-gel method for the catalytic hydrogenation of turpentine in order to investigate the catalytic activity of catalyst,the hydrogenation products were analyzed by gas chromatography.The catalyst preparation conditions were studied,the suitable preparation conditions of the catalysts were obtained:Ni content 35%,molar ratio of composite carrier 0.25,carrier calcination temperature 500℃,calcination time 5h,reduction temperature 500℃.(2)The process conditions of turpentine hydrogenation catalyzed supported Ni/TiO2-SiO2 catalysts was investigated by single factor and orthogonal experiments,the optimum conditions of reaction were obtained:the reaction pressure 5.5MPa,the reaction temperature 160℃,the reaction time 150min,2.5%of the catalyst as raw material quality,turpentine 20mL.Under these conditions,the conversion rate ofα-pinene was above 99%,and the selectivity of cis-pinane was 93.14%.Reproducibility experiments were conducted in this condition,the results showed that the catalyst had better activity,and the repeatability was better.The investigation experiments of catalyst life showed that the catalyst were continuously used for 5 times,the conversion of α-pinene was still above 90%,the selective of cis-pinane could reach 93%.(3)Supported Ni/TiO2-SiO2 catalysts was characterized using XRD,XPS,TG-DSC,TPR,BET and SEM.The result showed that the degree of crystallization was greatly improved when the compound calcined at 500℃,and forming anatase with high surface activity;The catalyst had a good thermal stability and the surface of uniform particle distribution under suitable calcination conditions;the catalysts with high specific surface area,up to 379m2/g;the catalysts activity was reduced with the active ingredient loss and some raw materials and products coated.This paper firstly adopts the supported Ni/Ti2-SiO2 catalyst for hydrogenation of α-pinene,with low price of nickel as the active ingredient,instead of the expensive noble metal catalyst,not only shorten the reaction time,and better stability of the catalyst.