α-Alumina-Supported Nickel Catalysts Prepared with Nickel Acetylacetonate. 2. A Study of the Thermolysis of the Metal Precursor

Abstract

The thermolysis of nickel acetylacetonate supported on α-alumina has been investigated by thermal methods (TGA-DTG-DTA), infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). At 250 °C and in static air atmosphere, decomposition of the metal ligands is nearly complete. Higher temperatures are needed in an inert atmosphere or in a vacuum. The variation of XPS peak parameters of samples heated at various temperatures between 120 and 900 °C has been interpreted as a change of the distribution of the Ni species between the octahedral and tetrahedral aluminum sites of the support, and a progressive formation of a nickel aluminate-like species, in agreement with temperature-programmed reduction features.

Synthesis and characterisation of highly dispersed Ni/SiO2 catalysts prepared by gas-phase impregnation/decomposition (GPI/D) of a Ni(II) ?-diketonate precursor complex

“…At the same time, the band at 1473 cm )1 , attributed to the d(CH3) vibrations of the (tmen) ligand, strongly decreases in intensity. In short, the spectrum on the adsorbed Ni species becomes very similar to that observed for [Ni(acac) 2 ], pure or adsorbed on silica [6][7][8]. Moreover, the absence of bands at 1730 and 1710 cm )1 , typical of pure Hacac, indicate that all (acac-) groups on the sample are bound to Ni centres.…”

“…Even though different models have been proposed by other authors for the species adsorbed from [Ni(acac) 2 ] precursors on alumina or on silica [6][7][8]10], our hypothesis is quite reasonable if one considers the coordination chemistry of Ni 2+ with (acac) ligands [22]. For instance, it has long been known that the molecular structure of [Ni(acac) 2 ] contains polymerised {Ni(acac) 2 } 3 units arranged in such a way that the Ni 2+ is always hexacoordinated, with six oxygen atoms in bridging positions [23].…”

“…Although supported nickel catalysts prepared from acetylacetonate complexes showed promising properties both in dispersion [3] and in stability during catalysis [4], only a few results have been reported for catalysts prepared from Ni acetylacetonate precursors in solution [4][5][6][7], and even less are reported for catalysts prepared by the GPI-D method [8][9][10].…”

Mechanism of Ni Film CVD with a Ni(Ktfaa)2 Precursor on a Silicon Substrate

“…Besides, the same shift has been assigned to non-stoichiometric Ni 3+ . [17] We know nothing about the C, O, N, and Ni elemental distribution in the film volume and the use of traditional layer ion etching with X-ray photoelectron spectroscopy (XPS) analysis for the clustered film is unfruitful. Binding Energy, eV The resistivity of the Ni film on the silicon substrate was found to be 210 ±4 X cm, higher than that of bulk Ni (6.84 10 ±6 X cm) and Ni film on a copper substrate.…”

Growth of Atomically Smooth Epitaxial Nickel Ferrite Films by Direct Liquid Injection CVD

“…Based on thermal stability studies of the precursors, the preferential incorporation of iron may be attributed to the lower thermal stability of Fe(acac) 3 than Ni(acac) 2 . [32][33][34] The effect of high oxygen flow rate, double of what is needed for growth of smooth and stoichiometric films (Table 2), is studied in the second control experiment. As shown in Figure 2b), a relatively smooth and dense film is obtained.…”