جستجوی مقالات مرتبط با کلیدواژه « catalytic activity » در نشریات گروه « مواد و متالورژی »

The xerogel samples were prepared by hydrolysis and condensation of tetraethyl orthosilicate (TEOS) by the sol-gel method. In this investigation, a new molar ratio of H2O/TEOS was determined to be 11.7. Also, the necessary amounts of tri-hydrated copper nitrate and penta-hydrated copper sulfate were added to the solution in such a manner that the concentration of the copper oxide in final solution reach to 10-12 wt %. After ambient drying, the xerogel samples were heated at 400, 600, and 800˚C at a slow heating rate (50°C/h). The structural properties were characterized by Transmission Electron Microscopy (TEM), Brunauer, Emmett and Teller theory for specific surface area determination (BET) and Thermal Program Reduction (TPR) methods at different temperatures. Finally, characterization of nano-composites was studied for NH3 selective catalytic reduction (NH3-SCR) of NO in gas phase. The results were presented the systematic reactivity study of NO reduction by NH3 on dispersed copper oxide nano-composites over silica supports, in order to determine the ability of these materials to convert into harmless species at different temperatures.

Pure and ZnO-doped Ni0.1Co0.9Fe2O4 catalyst were prepared by co-precipitation method and thermal decomposition in air calcinated at 400-700°C and that treated with different amounts of zinc nitrate (0.46-2.25 w% ZnO). X-ray powder diffractometry, scanning electron microscopy (SEM) and BET analysis of nitrogen adsorption isotherms investigated the crystalline bulk structure and the surface area of pure and doped samples, respectively. The hydrogen peroxide decomposition activity was determined by oxygen gasometry of the reaction kinetics at 20-40°C. The results revealed that the treatment of Ni0.1Co0.9Fe2O4 with ZnO at 400-700°C brought about a significant increase in the specific surface area and catalytic activity of Ni0.1Co0.9Fe2O4 on decomposition of hydrogen peroxide. However, the catalytic activity of H2O2 decomposition on Ni0.1Co0.9Fe2O4 calcined at different temperatures was found to show a considerable increase by doping with ZnO. They were discussed with UV/VIS spectroscopy which the energy band gap of the synthesized Ni0.1Co0.9Fe2O4 nano structure was calculated to be ~5 eV.