In situ diffraction studies of Ni nanostructure growth using microporous materials as supports.

摘要

Our objective is to study the growth mechanism of Ni nanostructures supported in microporous materials using X-ray diffraction. Since only the surface atoms of a catalyst are active, our aim is to find the optimum synthesis conditions for the formation of small Ni nanostructures. A state-of-the art XRD attachment called Reactor X was used to study the growth of the Ni nanostructures in situ. Our main focus was the study of the calcination and reduction of nickel acetate, as Ni metal precursor, impregnated into the one-dimensional channels of microporous VPI-8 and mordenite. Using the Reactor X we observed in the XRD diffraction patterns the appearance of nickel oxide (NiO) and Ni peaks during the calcination and reduction reactions, respectively. Among the most significant findings we found that the optimal reduction temperature that leads to the formation of metallic Ni crystals depends significantly on the metal loading and on the calcination.