2.8NiO–H1.8Ni0.6(OH)MoO4—Novel nanocomposite material for the reactive adsorption of sulfur-containing molecules at moderate temperature

It has been found that a poorly crystalline green precipitate that forms in boiling ammonia solution of Ni(NO3)2 and (NH4)6Mo7O24 yields on annealing a Ni-rich material (Ni/Mo = 3.4) containing slit shaped mesopores and exhibiting the BET surface area of 230 m2/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 H1.8Ni0.6(OH)MoO4 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 (NH4)HNi2(OH)2(MoO4)2 prepared in the similar conditions. The obtained nanocomposite 2.8NiO–H1.8Ni0.6(OH)MoO4 can be completely reduced in H2 flow at 300 °C yielding unsupported Ni3.4Mo bimetallic nanoparticles (D = 3.6 nm) which are stable towards sintering. The material shows remarkable activity in a moderate temperature reactive adsorption of thiophene: at 300 °C the rate of its sulfidation in the presence of thiophene is an order of magnitude higher than that of conventional Ni/ZnO sorbent. Such increase of activity is attributed to formation (after partial sulfidation) of the mixed Ni–Mo–S phase, which is known to be highly active in catalytic hydrodesulfurization of sulfur-containing molecules. Also, due to its open structure the nanocomposite reacts rapidly and completely with H2S even at 200 °C, while only the surface sulfidation is observed for ZnO nanoparticles under the same conditions.

We report preparation of novel mesoporous nanocomposite 2.8NiO–H1.8Ni0.6(OH)MoO4 consisting of Ni–Mo (hydr)oxide layers pillared with NiO particles. Due to enhanced HDS activity the material exhibits much higher reactivity towards sulfur-containing molecules than Ni/ZnO.Figure optionsDownload as PowerPoint slideHighlights
► New layered material is synthesized: 2.8NiO–H1.8Ni0.6(OH)MoO4.
► The material is mesoporous with BET surface area of 230 m2/g.
► NiO nanoparticles play the role of pillars between the Ni molybdate layers.
► In H2 flow at 300 °C the solid is reduced to Ni3.4Mo nanoparticles.
► The solid reacts with thiophene at 300 °C 10 times faster than Ni/ZnO.