ABSTRACT
Here we describe a new chemical route for obtaining highly dispersed nanometric Ni particles embedded in different matrices based on Al2O3, MgO, and TiO2 and in the heterogeneous matrices CeO2-doped Al2O3 and MgO-doped Al2O3. The synthesis method is based on a modification of the polymeric precursor method. The Ni nanoparticles (particles in the range of 1-40 nm) were obtained in a single process, without the use of an external reducing agent (hydrogen atmosphere).
Subject(s)
Crystallization/methods , Magnesium Oxide/chemistry , Nanotechnology/methods , Nanotubes/chemistry , Nanotubes/ultrastructure , Nickel/chemistry , Titanium/chemistry , Aluminum Oxide/chemistry , Macromolecular Substances , Manufactured Materials , Materials Testing , Metals/chemistry , Molecular Conformation , Oxides/chemistry , Particle SizeABSTRACT
Stable Ni nanoparticles embedded in a mesoporous silica material were used as catalysts for the conversion of methane into synthesis gas. This catalyst has the singular properties of controlling the carbon deposition and deactivation of active sites. A comparative study of our nanocomposites with conventional catalysts showed that impregnation material presented a preferential encapsulation and growth of carbon nanotubes on the metal surface. The impregnated catalyst showed a higher tendency for carbon nanotube and whiskers formation.
Subject(s)
Carbon Dioxide/chemistry , Crystallization/methods , Methane/chemistry , Nickel/chemistry , Silicon Dioxide/chemistry , Carbon/chemistry , Carbon Monoxide/chemical synthesis , Catalysis , Hydrogen/chemistry , Manufactured Materials , Microspheres , Molecular Conformation , Nanotubes, Carbon/chemistry , Particle Size , Quality ControlABSTRACT
Here we describe a new route for the synthesis of nanometric Ni particles embedded in a mesoporous silica material with excellent potential for catalytic applications. Mesoporous silica with a surface area in the range of 202-280 m2/g, with narrow pore size distribution and Ni nanoparticles (particles in the range of 3-41 nm) were obtained in a direct process. A different approach was adopted to process such a nanocomposite. This new approach is based on the formation of a polymer with the silicon oxianion and nickel cation chelated to the macromolecule structure and on the control of the pyrolysis step. The CO/CO2 atmosphere resulting from the pyrolysis of the organic material promotes the reduction of the Ni citrate.
