Preparation of a Pt/SiO2 catalystII. Temperature-programmed decomposition of the adsorbed platinum tetrammine hydroxide complex under flowing hydrogen, oxygen, and argon

Goguet, Alexandre; Schweich, D.; Candy, Jean‐Pierre

doi:10.1016/s0021-9517(03)00189-1

Cited by 39 publications

(31 citation statements)

References 37 publications

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“…The autoreduction of platinum catalysts at low temperature produced small platinum particles by avoiding the formation of large sinterings. The careful temperature-programmed decomposition of platinum tetraamine hydroxide impregnated on silica was recommended to obtain high platinum dispersion at loadings up to 5 wt.% [13]. However, platinum catalysts supported on silica usually show a rapid decrease in the platinum dispersion at higher temperatures.…”

Section: Introductionmentioning

confidence: 99%

Preparation of Highly Dispersive and Stable Platinum Catalysts Supported on Siliceous SBA-15 Mesoporous Material: Roles of Titania Layer Incorporation and Hydrogen Peroxide Treatment

et al. 2008

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Roles of titania layer incorporation and hydrogen peroxide treatment in the preparation of highly dispersed platinum catalysts supported on siliceous SBA-15 mesoporous materials were studied by examining the catalysts at each step of the preparation. XRD, TEM, XPS, Raman, IR, CO chemisorptions, EXAFS and XANES techniques were employed to the investigation of the physico-chemical states of platinum and titanium. The platinum particles were uniformly dispersed on SBA-15 ranged from 1 to 2 nm in size by incorporating titania onto the surface of SBA-15 and then treating the impregnating platinum precursor with hydrogen peroxide, even at platinum loading as high as 4 wt.%. The platinum catalysts showed considerably higher catalytic activity in the combustion reactions of both carbon monoxide and methane, suggesting a suitable catalyst for purifying diesel engine exhaust.

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Section: Introductionmentioning

confidence: 99%

Preparation of Highly Dispersive and Stable Platinum Catalysts Supported on Siliceous SBA-15 Mesoporous Material: Roles of Titania Layer Incorporation and Hydrogen Peroxide Treatment

et al. 2008

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“…Interactions between the precursor and the support may be created during the impregnation step or thermal post-treatments by exchange of the ligand with hydroxyl groups of the support and progressive formation of oxide particles. Operating conditions such as pH of the solution, duration of impregnation, atmosphere of thermal treatment, are parameters controlling the final dispersion of the particles [17,18].…”

Section: Introductionmentioning

confidence: 99%

Synthesis of highly dispersed palladium alumina supported particles: Influence of the particle surface density on physico-chemical properties

Benkhaled

Morin

Pichon

et al. 2006

Applied Catalysis A: General

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Complexation with nitrite ions in aqueous medium was used to prepare highly dispersed Pd8 particles supported on alumina. It has been possible to obtain catalysts with different Pd loading keeping the particle size lower than 1 nm as shown by HRTEM, chemisorption, or extended X-ray absorption fine structure (EXAFS) characterizations, and as a consequence with different particle surface density. We observed that electronic properties measured by IR(CO) or X-ray photoelectron spectroscopy (XPS) measurements are strongly influenced by this last parameter and that the origin of these variations can be related to the different strengths of the interactions of the palladium precursor with the alumina surface sites as shown by low temperature CO adsorption followed by FTIR spectroscopy. On increasing Pd loading, saturation of unsaturated Lewis surface sites follows their acid strength: the more acidic ones are the first to react as germination sites, followed by the medium and finally the weaker sites. These different interactions may explain the variation of electronic properties of such small reduced particles which appears to be very sensitive to the chemical nature of their initial germination site on the oxide support. On the other hand, no such effects were observed on changing the type of alumina (d or g) support, in agreement with the principle of the synthesis method which tends to limit strong interaction with the support. Comparison with Pd8 particles with the same particle size and particle surface density but prepared with the well known grafting of acetylacetonate precursor shows marked differences in terms of electronic properties followed by CO FTIR. This result illustrates the possibility to prepare highly dispersed Pd particles with different physico-chemical properties. #

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“…The starting Pt/SiO 2 catalyst (AG65) was prepared from Pt(NH 3 ) 4 (OH) 2 (Aldrich) and silica Aerosil from Degussa (200 m 2 /g), following the procedure already described [22,23]. The metal loading was 1.35% wt and the metal particle size was close to 1.5 nm with a very narrow size distribution.…”

Section: Methodsmentioning

confidence: 99%

Evidence for direct observation by Mössbauer spectroscopy of surface tin atoms in platinum–tin particles

et al. 2005

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119 Sn Mössbauer spectroscopy at 77 K was used to observe surface tin atoms on PtSn x /SiO 2 catalysts. Two families of PtSn x /SiO 2 catalysts with fully reduced Pt (0) and Sn (0) atoms were prepared following the Surface Organo-metallic Chemistry on Metal strategy. These two families of catalysts exhibit about the same Sn/Pt composition, but very different metallic particle diameters, each with narrow particle size distribution, so that, the ratio between surface tin atoms and "bulk" tin atoms was significantly different for the two families. In addition to the well known "Pt-Sn" bulk alloy with small quadripole splitting, a new Pt-Sn species with large quadripole splitting and isomer shift in the range of Sn (0) was observed. The relative proportion of this species with respect to "Pt-Sn" bulk alloy is greater for small particles than for the larger ones, which suggests that this species is a surface tin atom present in a "Pt-Sn" alloy.

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Preparation of a Pt/SiO2 catalystII. Temperature-programmed decomposition of the adsorbed platinum tetrammine hydroxide complex under flowing hydrogen, oxygen, and argon

Cited by 39 publications

References 37 publications

Preparation of Highly Dispersive and Stable Platinum Catalysts Supported on Siliceous SBA-15 Mesoporous Material: Roles of Titania Layer Incorporation and Hydrogen Peroxide Treatment

Preparation of Highly Dispersive and Stable Platinum Catalysts Supported on Siliceous SBA-15 Mesoporous Material: Roles of Titania Layer Incorporation and Hydrogen Peroxide Treatment

Synthesis of highly dispersed palladium alumina supported particles: Influence of the particle surface density on physico-chemical properties

Evidence for direct observation by Mössbauer spectroscopy of surface tin atoms in platinum–tin particles

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