文摘
Mesoporous multimetal oxide microspheres (Ni–Ce–Al–O) with tuned and uniformly distributed composition are prepared through an aerosol-assisted self-assembly approach and further used as catalysts for ammonia decomposition. The as-prepared and spent materials are characterized by various techniques including ex situ/in situ X-ray diffraction (XRD), X-ray absorption fine structure (XAFS), scanning electron microscope (SEM)/transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), and N2-adsorption. The tricomponent Ni–Ce–Al–O catalysts show great superiority over pure NiO or bicomponent catalysts (Ni–Ce–O and Ni–Al–O) in both catalytic activity and durability. By using H2-TPR combined with in situ XRD, we have identified metallic Ni0 as the active crystalline phase and further confirmed the strong interaction between alumina and other components. This strong interaction helps suppress the growth of both metallic Ni0 as active site and ceria as promoter under the harsh catalytic conditions (high temperature and reducing atmosphere) and thus improves the activity and stability simultaneously.