核壳结构镍基纳米催化剂的制备及其在肉桂醛加氢反应中的性能  

Preparation of nickel based core-shell catalysts and their catalytic hydrogenation of cinnamaldehyde

作　　者：牛立博[1] 刘辰 马苑媛 张慧玲 白国义[1] 

机构地区：[1]河北大学化学与环境科学学院,河北保定071002

出　　处：《化工学报》2017年第11期4161-4168,共8页CIESC Journal

基　　金：国家自然科学基金项目(21376060;21676068);河北省自然科学基金项目(B2016201167);河北省高等学校科学技术研究项目(QN2015037)~~

摘　　要：分别以硝酸镍和氯化镍为镍源,利用热分解法和水合肼还原法制得镍纳米粒子,再经模板剂造孔法在镍核外部包裹一层介孔壳,通过焙烧和氢气还原制备了核壳结构催化剂Ni@mSiO_2和Ni-N2H4@mSiO_2,并以肉桂醛加氢为探针反应考察了核壳结构镍基催化剂与负载型镍基催化剂的加氢性能。结果表明,核壳结构镍基催化剂在肉桂醛加氢反应中比共沉淀法制备的负载型镍基催化剂具有更高的活性,氢化肉桂醛的收率可达90%以上。同时,Ni-N_2H_4@mSiO_2催化剂具有较高的磁饱和度,可实现该催化剂在反应后高效回收并循环套用。采用X射线衍射、比表面及孔分析、透射电子显微镜、H_2-程序升温还原和H_2-化学吸附等表征手段,研究了所制催化剂的结构特征,初步探讨了催化剂结构与性能的构效关系。Two novel magnetic mesoporous core-shell nanocomposites Ni@mSiO2 and Ni-N2H4@mSiO2 were prepared by a surfactant-templating method.Nickel nanoparticles were first obtained from nickel nitrate or nickel chloride by thermodecomposition and hydrazine hydrate reduction,then covered by a mesoporous shell,and finally by sinteration and hydrogen reduction.As a comparison,Ni/mSiO2 carrier supporting catalyst was prepared by the traditional coprecipitation method.The core-shell nanocomposite of nickel nanoparticle core and mesoporous silica shell was characterized by transmission electron microscopy,X-ray diffraction and nitrogen adsorption-desorption.Temperature programmed H2 reduction indicated that NiO in these catalysts were mainly present in bulk phase and some small Ni O particles in Ni-N2H4@mSiO2 were easily reduced.H2-chemsorption results demonstrated that Ni/mSiO2 had more active sites but lower TOF value compared to core-shell Ni@mSiO2 and Ni-N2H4@mSiO2 catalysts.Both Ni@mSiO2 and Ni-N2H4@mSiO2 showed higher activity and better selectivity than Ni/mSiO2 in selective hydrogenation of cinnamyl aldehyde to hydrocinnamaldehyde,with over 90% yield of hydrocinnamaldehyde.Due to high magnetic saturation value of Ni-N2H4@mSiO2,it can be easily recycled for reuse by an external magnetic field.Notably,Ni-N2H4@mSiO2 showed better stability in hydrogenation.

关 键 词：催化剂 纳米粒子 加氢 核壳结构 构效关系 

分 类 号：TQ032[化学工程]