XPS analysis of the oxidation of palladium model catalysts

Voogt, E.H.; Mens, A.J.M.; Gijzeman, O.L.J.; Geus, J.W.

doi:10.1016/s0920-5861(98)00313-7

Cited by 28 publications

(10 citation statements)

References 8 publications

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“…This oxide may be formed on the surface of metallic Rh particles in the composites because of their oxidation in air. Such oxidation has been observed in the case of noble metals 37. This conclusion is consistent with the results of EDX investigations which clearly show the presence of oxygen in the Rh‐rich regions of PPy–Rh composites (Section 3.2).…”

Section: Resultssupporting

confidence: 89%

Preparation and characterization of polypyrrole with dispersed metallic rhodium particles

Stochmal

Hasik

Turek

et al. 2011

Polymers for Advanced Techs

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Polypyrrole (PPy) with dispersed metallic Rh particles has been prepared by all‐chemical route, i.e. reduction of Rh3+ ions existing in RhCl3 aqueous solutions with sodium borohydride (NaBH4) carried out in the presence of the previously obtained PPy doped with chloride ions (PPyCl). PPy–Rh composites thus formed have been characterized using X‐ray diffraction (XRD), scanning and transmission electron microscopies (SEM, TEM) combined with energy dispersive X‐ray (EDX) microanalysis, Rh3d X‐ray photoelectron (XPS), and IR spectroscopies. This has made it possible to find out that metallic Rh nanoparticles, mainly of sizes below 10 nm, have been present in the composites. Agglomerates, with sizes up to 0.7 µm, have been formed in the systems containing higher amounts of Rh. PPy serving as the matrix in the composites has been doped. However, its doping level has been lower than that of the starting PPyCl. This has been explained by partial reduction of the polymer occurring during preparation of the composites. Catalytic properties of the PPy–Rh systems have been investigated using isopropyl alcohol conversion as a test reaction. It has been established that the composites are active redox catalysts. This makes them promising materials for applications as catalysts of various redox processes. Copyright © 2010 John Wiley & Sons, Ltd.

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Section: Resultssupporting

confidence: 89%

Preparation and characterization of polypyrrole with dispersed metallic rhodium particles

Stochmal

Hasik

Turek

et al. 2011

Polymers for Advanced Techs

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“…Additionally, oxygen atoms occurring in the PPy-Rh composites studied in this work may result from partial surface oxidation of rhodium particles taking place in air and yielding metal oxide. Such phenomenon has been observed for noble metals [25]. In the spectra of Pt-containing composites the O1 s line, located close to the Pt4p 3/2 signal, is also seen.…”

Section: Characterization Of the Compositessupporting

confidence: 66%

Application of Conjugated Polymer–Platinum Group Metal Composites as Heterogeneous Catalysts

et al. 2008

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Composites of polyaniline (PANI) or polypyrrole (PPy) doped with chloride ions and Pt or Rh particles were prepared by chemical reduction of metal ions conducted in the presence of the polymers. Based on X-ray diffraction studies it was established that the composites contained metal nanoparticles (5-9 in size). However, according to SEM investigations metal particles were agglomerated (40 nm-1.1 lm in size). Redox activity of the composites in the catalytic isopropyl alcohol conversion was ca. ten times higher than the acid-base one. Pt dispersed in polymer matrices showed higher catalytic activity than Rh. PPy doped with chloride ions had a promoting effect on the activity of Pt catalysts.

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“…The XPS spectra of Pd 3d for the fresh and aged catalysts are shown in Fig.2, and the BE values of Pd 3d 5/2 are listed in Table 1. In general, the binding energy of Pd 3d 5/2 for Pd 0 and Pd 2+ are about (334.9±0.1) eV and (336.4±0.1) eV [23] , respectively. As shown in Table 1, the binding energy of Pd 3d 5/2 of fresh and aged catalysts falls in the range of 334.9~ 336.4 eV, indicating that the Pd species in fresh and aged [24], the core-level binding energy of Pd mainly depends on the particle size of PdO x and the energy value of Pd 3d 5/2 decreases with the rise of PdO x particle size supported on Al 2 O 3 , indicating that the particle size of PdO x become larger after aging treatment.…”

Section: Xps Resultsmentioning

confidence: 95%

“…The average Pd particle size, d (nm), was obtained by 1.12/D [21] , where D (%) is the dispersion of Pd. The active Pd surface area, S (m 2 /g), was approximated by 23 ), δ is the atomic cross section of Pd (0.06 nm 2 ) [22] , w (g) is the mass of catalyst, and p (%) is the mass fraction of Pd.…”

Section: Co Chemisorption Analysismentioning

confidence: 99%

Catalytic Activity of C 3 H 8 over Fresh and Aged Pd/Al 2 O 3 Close-Coupled Catalysts

Fang

Cui

Shi

et al. 2017

Rare Metal Materials and Engineering

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The Pd/Al2O3 close-coupled catalysts supported on modified alumina were prepared by an impregnation method, and then characterized by H2-temperature programmed reduction (H2-TPR), CO chemisorption, and X-ray photoelectron spectroscopy (XPS). Both total catalytic activity and single reactions in related to C3H8 conversion were tested in simulated exhaust gas. The results show that the amount of active PdOx decreases and negative metallic Pd 0 appears during aging treatment. The light-off temperature (T50) and complete conversion temperature (T90) increase by 76 º C and 64 º C, respectively. After aging treatment, signifying that the low-temperature activity decreases more obviously than high temperature property. The results of comparison among single reactions indicate that the light-off activity of reactions which occur in atmosphere with the participation of NO but without H2O injection decreases dramatically after the aging treatment. The inhibitive effect of NO on light-off activity and the positive effect of H2O on high temperature property become obvious during the aging treatment.

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XPS analysis of the oxidation of palladium model catalysts

Cited by 28 publications

References 8 publications

Preparation and characterization of polypyrrole with dispersed metallic rhodium particles

Preparation and characterization of polypyrrole with dispersed metallic rhodium particles

Application of Conjugated Polymer–Platinum Group Metal Composites as Heterogeneous Catalysts

Catalytic Activity of C 3 H 8 over Fresh and Aged Pd/Al 2 O 3 Close-Coupled Catalysts

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