Reaction of thiophene with mono- and bimetallic Ni–Co particles supported on γ-Al2O3 and HDS activities of obtained sulfides
Abstract Reaction between thiophene and M/γ-Al2O3 (20 wt.%, M = Ni, Co, 2Ni–Co and 2Co–Ni) was studied by thermal gravimetric analysis (TGA) and by sulfidation in a fixed bed microreactor. The samples were prepared by incipient wetness impregnation followed by drying and reduction in hydrogen flow at 450 °C. Formation of bimetallic particles in samples containing both Ni and Co was confirmed by HRTEM with EDX analysis. The reaction with thiophene (20 or 40 mbar) was done at 360 °C in hydrogen atmosphere. TGA of the reaction with thiophene revealed that the initial rate of sulfidation drops sharply when going from Ni/γ-Al2O3 to Co/γ-Al2O3 (by a factor of 40 under used conditions). It follows…
Sulfidation Mechanism of Pure and Cu-Doped ZnO Nanoparticles at Moderate Temperature: TEM and In Situ XRD Studies
International audience; Sulfidation mechanism of pure and Cu-doped ZnO nanoparticles (Cu0.03Zn0.97O and Cu0.06Zn0.94O) at 250 and 350 degrees C was studied by transmission electron microscopy (TEM) and in situ synchrotron XRD. For nondoped ZnO, we observed by TEM that partial reaction with H2S is accompanied by the formation of voids at the ZnO/ZnS interface. This phenomenon (known as the Kirkendall effect) confirms that sulfidation of nanosized ZnO by gaseous H2S proceeds via the outward growth of ZnS: Zn2+ and O2- are transferred to the external (ZnS/gas) surface, where zinc is combined with sulfur and oxygen reacts with protons yielding H2O. During sulfidation of Cu-doped ZnO, the caviti…
Low Temperature H2S Removal with Metal-Doped Nanostructure ZnO Sorbents: Study of the Origin of Enhanced Reactivity in Cu-Containing Materials
Sulfidation of pure and metal-doped ZnO nanostructure sorbents (M0.03Zn0.97O, M = Fe, Co, Ni, Cu) was studied in order to clarify the effect of metal on the transformation kinetics at 200−350 °C. The solids were prepared by coprecipitation from metal nitrate solution followed by calcination at 400 °C. Reaction with H2S was studied by thermal gravimetric analysis (TGA) using a gas mixture containing 0.2 vol % H2S in equimolar H2−N2. It was found that at 350 °C the TGA sulfidation profiles of all studied samples are similar, with the interface reaction being the main rate-determining step. After lowering the temperature to 250 °C the transformation of Cu0.03Zn0.97O continues to be controlled …
2.8NiO–H1.8Ni0.6(OH)MoO4—Novel nanocomposite material for the reactive adsorption of sulfur-containing molecules at moderate temperature
Abstract It has been found that a poorly crystalline green precipitate that forms in boiling ammonia solution of Ni(NO 3 ) 2 and (NH 4 ) 6 Mo 7 O 24 yields on annealing a Ni-rich material (Ni/Mo = 3.4) containing slit shaped mesopores and exhibiting the BET surface area of 230 m 2 /g. Characterization of the material by TGA, XRD, TEM, SEM, and EXAFS allowed to determine that it is a nanocomposite consisting of Ni–Mo (hydro)oxide layers H 1.8 Ni 0.6 (OH)MoO 4 which are pillared by NiO nanoparticles ( D = 3 nm). The structure of the layers appears to be similar to that found in the previously described crystalline molybdate (NH 4 )HNi 2 (OH) 2 (MoO 4 ) 2 prepared in the similar conditions. T…