Study On Preparation Of Ni Hollow Spheres Using PS Beads As Physical Template

With the development of nano-science,nano-materials are the important aspects and have become the central issue in the field of materials science. As the nanoporous materials has small size, large porosity, a significant surface effect and high surface area, it becomes a new excellent material with dual functional and structural attributes, which is widely used in every fields, such as environmental materials, energy saving and other green materials, efficient filter and separating materials, fuel cell, muffler and damping materials, electromagnetic shielding materials, catalytic materials and so on. At present, there are many ways to prepare metal materials with nano-porous, some main methods such as metal powder sintering, de-alloying, oblique incidence deposition, colloidal crystal template method. In this paper,it was reported a new method to prepare the organic/inorganic nanocomposite materials and nanoporous metal materials with uniform coating and aperture by optimizing of experimental conditions, respectively.In this paper,firstly, monodisperse PS microspheres with diameter of 120 nm were prepared by miroemulsion polymerization method. Then the effect of monomer amount, reaction temperature, initiator and emulsifie amount on size of PS microspheres were studied. The measured average particle size of polystyrene microspheres becomes bigger with the increasement of monomer and amount of initiator, but becomes smaller with the increasement of emulsifier concentration and reaction temperature under laboratory conditions, the best ratio of preparing PS microspheres was Styrene monomer (10 mL), potassium persulfate (0.25 g), and sodium dodecyl sulfonate (0.4 g). Secondly, electroless plating method by pd activation process and pd-free activation process was used to implant catalytic activity on the surface of PS microspheres, then PS/Ni microspheres were prepareted by optimizing of experimental conditions. SEM, EDS and FTIR were used to characterize these complexed microspheres. According to the experimental results, it has been obtained PS/ Ni microspheres with better dispersion, and the coating is more homogeneous and thicker compared to conventional chemical plating. Thirdly, based on the decomposition temperature of complexed microspheres, the hollow nickel microspheres with aperture of 100-130 nm, the shell thickness is about 15-20 nm were obtained by heating the PS/Ni microspheres at 500℃for 5 h in an oven with nitrogen flow,then studied the effect of different anneal temperatures on morphology of hollow nickel microspheres. XRD and N2 sorption was used to characterize these samples, it works out that hollow Ni sample has a face-centered cubic structure with good crystal, and basically, there is no introduction of other impurities. The Brunauer Emmett Teller (BET) specific surface areas of Ni is 161.69 m²Â·g^-1. Lastly, The hollow nickel microspheres were used to prepare 2,4-dimethylaniline by hydrogenation of 2,4-dimethylnitrobenzene. The results show that the hollow materials have catalytic effect on the hydrogenation reaction, but selectivity and catalytic activity are not ideal, Under laboratory conditions, the temperature of 50℃, pressure of 3.0 MPa, reaction temperature of 120 min, it measured that the yield of 2,4-dimethylaniline was 46 %, and the hydrogenation mechanism was discussed.