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Abstract LaAl 1-x Ni x O 3 (with x = 0.05 and 0.2) perovskite oxides were successfully synthesized and its behavior under reduction atmosphere was studied. HRTEM and STEM studies, coupled to HAADF and EDX detection, allowed to evidence the Ni exsolution process to the surface of the solid and to build nano-catalytic centers. The size of these centers is independent of the reduction conditions in the range studied. The high specific surface of the raw material, its porosity and the structure defects could be responsible of the low temperature at which the exsolution process starts. The content of Ni dopants allows the control of Ni centers size on the surface and the synthesis method provides Ni-nanoparticles strongly anchored to the resultant support. Graphical abstract Ni-nanoparticle strongly anchored to the LaAlO 3 support. Image 1 Highlights • Perovskites behavior under reducing atmosphere were studied. • Ni exsolution process to surface build nano-catalytic centers. • The size of Ni particles is independent on the reduction conditions in the range studied. • The content of Ni dopants allows the control of Ni centers size at the surface. • The synthesis method provides Ni-nanoparticles strongly anchored to the resultant support. [ABSTRACT FROM AUTHOR]

Solvothermal synthesis offers an important approach to prepare nickel particles with high crystallinity and low agglomeration. In this study, submicron nickel particles are prepared by a solvothermal approach involving alcohol reduction with the assistance of different types of organic bases. The influences of the types of organic bases and solvents, and the amount of organic bases on the particle size and morphology of nickel are studied. It is found that an organic base with a stronger alkalinity is able to generate nickel particles with smaller size. Smaller nickel particles are also prone to be obtained from solvents with a stronger reducing ability. Moreover, the formation mechanism of nickel particles is investigated. It is found that the nickel precursor and OH− form nickel layered hydroxide salts at the initial stage, and then the nickel layered hydroxide salts gradually dissolve to form nickel particles. Magnetic measurement reveals the morphology-dependent magnetic properties. Although the sample which has the smallest size exhibits a relatively high coercivity, samples which have a rather large particle size but consist of smaller primary nanoparticles also show relatively high coercivity values. [Display omitted] • Nickel submicron particles are synthesized via a solvothermal approach in alcohols. • Organic bases with stronger alkalinity are found to generate smaller particles. • Nickel particles with a narrow size distribution (182 ± 18 nm) are obtained. • The formation mechanism of nickel particles in solvothermal conditions is revealed. • Morphology-dependent magnetic properties are observed. [ABSTRACT FROM AUTHOR]

5wt% of Ni supported on activated carbon, Al 2 O 3 and Carbon covered Al 2 O 3 (C-Al 2 O 3 ) prepared by impregnation technique have been subjected to nitrobenzene hydrogenation at atmospheric pressure in vapour phase conditions. The catalysts were characterized by XRD, BET surface area, TPR and H 2 -Pulse chemisorption. Among the catalysts, Ni/C-Al 2 O 3 catalyst exhibited excellent and steady activity in the nitrobenzene hydrogenation at 498 K which can be attributed to the presence of smaller Ni particles with proper metal support interaction. [ABSTRACT FROM AUTHOR]