Nickel oxidative aggregation

The characterization of the latter materials by HRTEM (Fig. 7), EXAFS (Fig. 8), XPRD (Fig. 9) and XANES has unambiguously shown their surface to contain small (0.5-1 nm), highly dispersed and crystalhne Pd and Ni clusters, as bimetallic aggregates, Ni-0 as well as single Pd sites, likely stabilized by interaction with oxygen atoms from the nickel oxide. 

However, since the larger particles of oxide and metal nickel have almost the same size, it may be deduced that the particles are probably reduced without any important nickel migration. The same conclusion can be drawn for the standard impregnated INi samples aggregates of nickel oxide are reduced without significant Ni migration, m agreement with previous results [2, 6]. 

Among the nonnoble metals that can be synthesized by radiation-induced reduction in solution, nickel raises some difficulties because the atom formation and aggregation processes undergo the competition of oxidation reactions of highly reactive transients, such as monovalent Ni ion, Ni atom, and the very first nickel oligomers. Nevertheless, in... 

Sulphate of Nickel—Ni 0, SO, -j- 6 HO—which results from the action of sulphuric acid on the metal, or its oxide, crystallizes in green rhombic prisms these, when exposed to light, are converted, without loss of water, into small regular octohedra, aggregated together in the form of the original crystal, which becomes opaque. 

Sol-gel processes are also suitable for lanthanide oxide formation, as could be shown by the use of Tb(acac)3 and Dy(OBu- )3 in acetylacetone" . Tb203 crack- and pine-hole-free, dense and smooth microstructured buffer layers were produced on nickel tapes by a reel-to-reel continuous sol-gel process. The authors report that the film properties can be strongly influenced by solution components, temperature, time and atmosphere. Nanocrystalline mesoporous dysprosium oxide Dy203 with narrow monomodal pore size distribution can be approached by a combined sol-gel process with a surfactant-assisted templating technique . The spherical Dy203 nanoparticles were formed with aggregations. 

Phthalocyanlnes. Gebler (18) has reported the attachment of a variety of metal phthalocyanines to both 8% and 20% dlvlnylbenzene polystyrene copolymer beads. The attachment of the phthalocyanine unit was either ly a sulfonamide or a sulfone linkage. Nickel, vanadyl, cobalt, iron and manganese complexes were formed in this way. Since solution aggregation accounts for a diminution of the catalytic activity, it was anticipated that polymer immobilization would Increase reactivity. Such an effect was not observed and little advantage over the homogeneous catalysts could be observed in the oxidation of cyclohexene. Oxidations of thiols by immobilized phthalocyanines have been reported (19-20) by both Schutten and Brouwer. 

Qass II consists of electrically active dusts that lose their charge upon adhesion and may form strong aggregates. These include stack effluents of the zinc oxide type, raw cement, discharges from nickel smelting furnaces, magnesites, chromium ore, wheat starch, powdered sugar, and molybdenum oxide. 

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