Controllable Preparation And Properties Study Of Three-Dimensional Nickel Based Nanocomposite Catalysts

Supported metal catalysts are widely used in hydrogenation, dehydrogenation and catalytic reforming reaction, and they are one of the most important catalysts in petroleum refining and petrochemical process. The common supported metal catalyst carriers included metal oxides, zeolites and carbon materials (carbon nanotubes, graphene, etc.). Among them, the carbon material with excellent electrical conductivity and stability of its specific surface area, good has become a hot research point. The preparation methods of metal/carbon nano composite catalyst based on mixture precursor of carbon and metal, are a complex preparation process, high cost, poor uniformity, low purity. In this paper, we use a simple, economical, and single precursor organic small molecule scale intercalated layered double hydroxides method to synthesis homogeneous pure, good dispersion, high activity and stability of the 3D nickel carbon composite catalyst 3D Ni@C and titanium nickel-carbon composite catalyst 3D TiO2- three iterms Ni@C catalysts. The composition, structure and properties were studied. The specific contents are as follows:In this paper, a method of green, economy, large scale for small organic molecule intercalating hydrotalcite precursor was used in preparing controllable single particle size, high crystallinity, good dispersion three-dimensional nickel-carbon catalyst 3D Ni@C and and titanium-nickel carbon three items nano composites catalyst 3D TiO2-Ni@C. We studied the composition and their structure, and the specific contents are as follows:1. Using the small organic molecule salicylic acid intercalating nickel based hydrotalcite pure precursor, we modulated the ratio of salicylic acid and urea to achieve the controllable synthesis of 3D flowerlike precursor. Then we used the method of in situ solid-state pyrolysising at different calcination temperature to synthesize the 3D Ni@C catalyst with high metal loading, high activity and high stability of dispersion under an inert atmosphere. From the HRTEM, we saw the graphite carbon coated nickel particles size is only 6nm, and they can maintain a high degree of crystallinity and dispersibility. EDX, XPS and other testing means that:in the three dimensional nickel-carbon composite catalysts, the loading of Ni metal can reach above 50%, and in the metal nickel nanoparticles coated with carbon, metal Ni is interacted with carbon by the valence of " Ni-O-C". In the liquid phase hydrogenation of p-nitrophenol test, the catalyst efficiency of the 3D Ni@C catalyst was 7 times higher then the noble metal catalyst Pt@C, and they can be used for magnetic recycling. Therefore, the 3D Ni@C catalyst prepared by this method has the property of high dispersion, high metal loading and the high catalytic activity and stability.2. Using the co-precipitation methord to parapre the small organic molecule salicylic acid intercalating Layered Double Hydroxide nickel titanium pure precursors, we modulated the ratio of Ni2+ and Ti4+ to achieve the controllable synthesis of three-dimensional precursor.. Then use the method of in situ solid-state pyrolysis to prepare particle size controllable, high dispersion and magnetic recycling nickel-titanium-carbon nano composite catalyst 3D TiO2-Ni@C. The method successfully used the dispersion of metal ions Ni2+ and Ti4+ at the atomic level in the layers to keep the good dispersity and uniformity for the makes the metal nickel particles in situ solid-state pyrolysis and titanium dioxide particles. And the introduction of metal Ni can not only improve the activity of semiconductor TiO2 catalyst, but also add the function of magnetic recovery property at the same time. From the HRTEM, after calcination at a temperature of 500℃ under inert atmosphere, the carbon coated nickel particles can uniformly disperse around the TiO2 whose particles size is only around 8nm.This method was successfully introduced the magnetic properties into the catalysts and controled the particle size of TiO2 semiconductor catalyst at the same time.The preparation method has the advantages of simple process, green, without the need of expensive raw materials and equipment. The catalytic activity of the catalysts prepared by high, good dispersion, high stability, and can be magnetic recycling and reuse, and has broad application prospects.