Supported metals acetylacetonates

Aromatics such as benzene and toluene have also been used as a solvent for highly chelated metal complexes, such as in the preparation of supported metal acetylacetonates. Aromatics are a good choice for metal complexes formed with aromatic ligands such as bipyridil. Tetrahydrofuran (THF) has also been used as a solvent to prepare silica-supported Pd that was generated by the decoration of the surface with Pd(acac)2. °... 

Ommen, J. G. van, K. Hoving, H. Bosch, A. J. van Hengstum and P. J. Gellings. 1983. The preparation of supported oxide catalysts by adsorption of metal acetylacetonates, M(AcAc)n on different supports. Z. Phys. Chemie Neue Folge 134 99-106. 

Two types of catalysts were used in this study. One is the metal supported on an unreducible oxide and the other is their physical mixtures with another unreducible oxide. The unreducible oxides used were MgO Si02f and (X-AI2O3 Metals (M) were Ru Rh, Ni Pd and Pt. These were introduced through die corresponding metal acetylacetonate... 

One may apply the gas-phase technique to make large amounts of supported metal oxides by the following procedure. The powder of a metal oxide support may be confined as a fixed bed with the gaseous metal acetylacetonate (sublimed from a source at 180-200°C) transported through the bed by an inert carrier gas at a temperature sufficiently high to cause the reaction (>250°C). The extent of reaction between the metal source and the metal oxide support can be determined by monitoring the composition of pentanedione in the gas phase. The... 

Alcohols, such as methanol and ethanol, has been used as solvents for the metal acetylacetonate systems, usually under reflux conditions. For many of these metal acetylacetonates, these alcohols are good solvents and show only a low affinity for most supports. However, as we discussed earlier, some metal acetylacetonates form p-alkoxy dimers when catalytic amounts of OH are present. The unexpected formation of these dimeric precursors may frustrate attempts to form a supported metal oxide catalysts with isolated metal cations decorating the surface. 

Another ion exchange procedure involves the interaction of a metal acetylacetonate (acac) with an oxide support. Virtually all acetylacetonate complexes, except those of rhodium and ruthenium, react with the coordinatively unsaturated surface sites of 7 alumina to produce stable catalyst precursors. On thermal treatment and reduction these give alumina supported metal catalysts having relatively high dispersions. 38 Acetylacetonate complexes which are stable in the presence of acid or base such as Pd(acac)2, Pt(acac)2 and Co(acac)3, react only with the Lewis acid, Al" 3 sites, on the alumina. Complexes which decompose in base but not in acid react not only with the Al 3 sites but also with the surface hydroxy groups. Complexes that are sensitive to acid but not to base react only slightly, if at all, with the hydroxy groups on the surface. It appears that this is the reason the rhodium and ruthenium complexes fail to adsorb on an alumina surface. 38... 

The deposition of platinum, rhodium and ruthenium acetylacetonates on titania takes place by reaction with the surface hydroxy groups to give a supported complex. Thermal decomposition of these supported complexes in vacuum gave highly dispersed titania supported metal catalysts having metal particles about 2 nm in diameter. ... 

The infrared spectra 174) show no absorptions above 1600 cm , except for the C-H-stretching frequencies, thus supporting the conclusion that the products are free of hydrolytic impurities. The infrared spectra of M(acac)2X2, M(acac)gX, and M(acac)4 are generally similar to the spectra of other metal acetylacetonates in the chelating carbonyl stretching region. The observed carbonyl frequency shifts are in accord with the expectation that a coordination number increase results in a... 

Neyertz, C. and Volpe, M. (1998). Preparation of Binary Palladium-vanadium Supported Catalysts from Metal Acetylacetonates, Colloids Surf. A, 136, pp. 63-69. 

The approach comprises deposition-precipitation (DP) of Au(OH)3 onto the hydroxide surfaces of metal oxide supports from an alkaline solution of HAUCI4 [26] and grafting of organo gold complexes such as dimethyl gold (Ill)acetylacetonate (hereafter denoted as Au acac complex) [27] and Au(PPh3)(N03) [28] either in gas and liquid phase are advantageous in that a variety of metal oxides commercially available in the forms of powder, sphere, honeycomb can be used as supports. 

Gas-phase grafting (GG) is characteristic in that gold can be deposited even on the acidic surfaces, such as activated carbon and on Si02 [27]. The vapor of gold acac complex is adsorbed on the support powder probably through the interaction of electron-rich oxygen atoms in acetylacetonate and then calcined in air to decompose it into metallic gold particles. 

Chemical Treatment of Paper. Test samples were treated with aqueous copper(II) or iron(II) sulfate solutions or with nonaqueous copper(II) or iron(III) acetylacetonate solutions. All chemical treatments were designed to obtain extensive and uniform penetration into the paper structure. To facilitate contact between paper and solution and to provide physical support, test samples were interleaved with fibrous sheets of nonwoven polyester. Sorption of metal species from aqueous media was achieved by immersion of paper samples into the solution of choice for 16-18 h. The metal-catalyst content of paper was varied by adjusting the solution concentration. The concentration ol the aqueous metal salt solutions was varied from 10 3 to 10 1 M. One liter of solution was used for every 25 sheets of paper. At the end of the treatment period, paper samples treated in aqueous media were washed with water. 

Baltes, M., O. Collar , P. Van Der Voort, and E. F. Vansant, Synthesis of Supported Transition Metal Oxide Catalysts by the Designed Deposition of Acetylacetonate Complexes , Langmuir (1999), 15, 5841-5. 

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