Deposition-precipitation synthesis, supported

A Deposition-Precipitation Synthesis of Supported Metal Catalysts... 

Successful applications of the oxygen-modified CNFs are reported on immobilization of metal complexes ]95], incorporation of small Rh particles [96], supported Pt and Ru CNFs by adsorption and homogeneous deposition precipitation ]97, 98], Co CNFs for Fischer-Tropsch synthesis ]99], and Pt CNFs for PEM fuel cells [100]. 

A parameter that determines the performances, as outlined also in patents, is the mean diameter of Pd or doped-Pd particles. This is also one of the claims in Headwaters Nanokinetix Inc. patents. It seems that a maximum in the activity/ selectivity as a function of the particle size is present. Figure 8.11 reports the effect of the Pd-particle size (Pd supported on alumina, prepared by deposition-precipitation method) in the direct synthesis of H202 in water at atmospheric pressure [77]. Low... 

The deposition-precipitation method as proposed by Haruta et al. (1993) provides another way to synthesize composite materials with noble metal nanoparticles over metal-oxide supports. The synthesis of gold and platinum nanoparticles supported on various metal oxide substrates (such as Ti02, ZnO, Ce02, C03O4 and Fe203) (Bamwenda, Tsubota, Nakamura and Haruta 1995 Boccuzzi, Chiorino, Tsubota and Haruta 1996 Centeno, Carrizosa and Odriozola 2003 Moon, Lee, Park and Hong 2004 Zanella, Delannoy and Louis 2005 Li, Comotti and Schuth 2006) has been continually reported in the past one and a half decades. 

A detailed discussion of the deposition of metals on monolithic supports was presented by Vergimst et al. (75). The most popular methods are the same as those applied in typical catalyst synthesis, namely, impregnation, ion exchange, and deposition precipitation. 

S. Belochapkine, J. Shaw, D. Wenn, J.R.H. Ross, The synthesis by deposition-precipitation of porous gamma-alumina catalyst supports on glass substrates compatible with microreactor geometries, Catal. Today 110 (2005) 53. 

The applicability of the Pt deposition precipitation technique (DP) on mesoporous silica has been evaluated and discussed. A detailed synthesis procedure is given, and a suitable support from the SBA-15 family has been identified. The material synthesized at the conditions described here was clearly able to withstand the severe conditions of the DP treatment, indicating improved hydrothermal stability. The incorporation of the active species was accomplished without compromising the structural integrity of the parent material, as monitored by XRD and N2-sorption measurements. Using UV-Vis diffuse reflectance spectroscopy we were able to detect the platinum surface complex that coexists with platinum nanoparticles on the impregnated solid. 

In this contribution, sulfided Rh catalysts supported on CNTs were prepared by different methods including deposition-precipitation (DP), grafting, and polymer-assisted synthesis. The aim is to improve the dispersion of the aetive phase on CNTs, and enhance the catalytie aetivity and stability of the eatalysts under highly corrosive conditions. 

Au/Ce-Ti-O materials have been scarcely used in catalysis [1-5]. In the few available reports on the synthesis of this kind of materials, the Ce-Ti-O supports were synthesized by a sol-gel method [1,2,4,5] or by incipient wetness impregnation of aqrreorrs solution of cerimn nitrate on titania [3]. In these works, Au was loaded by Deposition-Precipitation [1-5]. We have previously synthesised Ce-Ti-O supports with different Ce/Ti molar ratios by solvothermolysis [6]. In the preserrt work, Ce-Ti-O supports, with higher Ce contents, were loaded with Au by a double impregnation method (DIM) [7], characterised by several techniques and tested for CO oxidatioa To the best of our knowledge, this is the first report with the combination of the solvothermal method for Ce-Ti-O synthesis with the DIM approaeh for gold loading. 

Catalyst synthesis by means of deposition precipitation comprises application of the active component onto an existing support via a chemical reaction. This reaction gives rise to the formation of an insoluble compound which involves the active element. The Insoluble compound can be formed by an increase of Che pH of the solution (hydroxide precipitation), a valence change of the element in question and the like. Under certain conditions, such as a suitable Interaction between the compound and the carrier, the preparation... 

A series of copper-zirconia catalysts have been prepared by methods of sequential precipitation, coprecipitation and deposition precipitation. The influence of various pretreatments and of the copper zirconia ratio on the structural and chemical properties of these samples are examined. High activity and selectivity of the catalysts is shown to be correlated to the presence of amorphous zirconia which is stabilized by copper ions. The results indicate that the structural and chemical properties of the support and particularly the interface copper/zirconia are most decisive in governing the catalytic properties of these methanol synthesis catalysts. 

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