Palladium, Palladium–Tin, and Palladium–Silver Catalysts in the Selective Hydrogenation of Hexadienes: TPR, Mössbauer, and Infrared Studies of Adsorbed CO

Sales, Emerson Andrade; Jové, J.; Mendes, Mário de Jesus; Bozon‐Verduraz, François

doi:10.1006/jcat.2000.2967

Cited by 66 publications

(32 citation statements)

References 24 publications

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“…To investigate the oxidation states and the accessibility of the exposed metals in the Pd-Sn catalysts, CO adsorption was followed by IR spectroscopy. For Sn_Al one band is observed at 2199 cm )1 (not shown), which can be ascribed either to adsorption of CO on Sn 4+ [34] or to CO interacting with A1 3+ on the alumina surface [35]. The band disappeared after evacuation of the cell at 25°C.…”

Section: Catalyst Characterizationmentioning

confidence: 94%

“…After evacuation at 298 K, the band at around 1988 cm )1 decreased in intensity and shifted to lower wave numbers, whereas the carbonyl species giving the band near 1930 cm )1 were unaffected. Sales et al [35] observed only one very broad band centred at 1980 cm )1 for Pd- Sn supported on alumina catalysts, a feature which they attributed this feature to three different types of bridged CO species adsorbed on metallic palladium. The band near 1930 cm )1 in the spectra ( figure 4 a, b) are ascribed to compressed bridged CO species adsorbed on high index planes of metallic Pd or to CO in threefold sites on Pd [35].…”

Section: Catalyst Characterizationmentioning

confidence: 96%

“…Sales et al [35] observed only one very broad band centred at 1980 cm )1 for Pd- Sn supported on alumina catalysts, a feature which they attributed this feature to three different types of bridged CO species adsorbed on metallic palladium. The band near 1930 cm )1 in the spectra ( figure 4 a, b) are ascribed to compressed bridged CO species adsorbed on high index planes of metallic Pd or to CO in threefold sites on Pd [35]. Sales et al [35] observed this band at 1930 cm )1 only for monometallic Pd/Al 2 O 3 catalysts.…”

Section: Catalyst Characterizationmentioning

confidence: 96%

“…The band around 2151 cm )1 is assigned to CO adsorption on residual Pd 2+ species [37], since interaction of CO with Sn 2+ at room temperature is very weak and does not produce measurable bands under these experiments conditions. Chloride ions, from the tin precursor, which are not fully removed by the reduction procedure, could stabilize these palladium ions [35]. The band decreased upon evacuation but did not disappear.…”

Section: Catalyst Characterizationmentioning

confidence: 98%

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Water Denitration over a Pd–Sn/Al2O3 Catalyst

et al. 2005

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Bimetallic Pd-Sn catalysts were synthesized by incipient-wetness impregnation of the metals on alumina and employed for the reduction of nitrates from aqueous solutions. The catalysts were characterized by FTIR spectroscopy of adsorbed CO, X-ray diffraction (XRD), transmission electron microscopy (TEM), and H 2 chemisorption. The influence of the metal ratio was evaluated in reaction measurements. The bimetallic Pd-Sn catalysts exhibited high selectivity for nitrate removal forming less NO 2 ) and NH 4 + than the Pd-Cu catalysts.

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Section: Catalyst Characterizationmentioning

confidence: 94%

Section: Catalyst Characterizationmentioning

confidence: 96%

Section: Catalyst Characterizationmentioning

confidence: 96%

Section: Catalyst Characterizationmentioning

confidence: 98%

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Water Denitration over a Pd–Sn/Al2O3 Catalyst

et al. 2005

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“…Other authors suggest that the consumption of hydrogen near these temperatures is due to the reduction of Pd η+ Cl x O y (0 < η < 2) species or to the reduction of Pd +2 ions stabilized by neighbouring Cl -, that were not eliminated during calcination and remain on the alumina surface. [26][27][28] Figure 3 shows that above 503 K multiple hydrogen consumption peaks appear due to the reduction of NiO species that interact with the support. The first peaks at 520-620 can be assigned to the reduction of NiO x with weak or null interaction with the support (bulk NiO).…”

Section: Catalysts Characterizationmentioning

confidence: 99%

MORE ACTIVE AND SULFUR RESISTANT BIMETALLIC Pd-NI CATALYSTS

Betti¹,

Carrara²,

Badano³

et al. 2017

Quim. Nova

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The influence of the kind of metal precursor and the sequence of impregnation on the properties of Pd-Ni catalysts was evaluated during the test reaction of selective hydrogenation of styrene to ethylbenzene by means of physicochemical characterization. The focus was put on the final hydrogenating activity and the resistance to deactivation by sulfided compounds (thiophene). The used techniques of characterization were ICP, XPS, XDR, TPR, CO chemisorption and TEM. XPS results indicated the presence of different Pd species: Pd δ-, Pd 0 and Pd δ+ . In the case of the Ni containing catalysts, Ni 0 and NiO species were also detected. These palladium and nickel species would be responsables of the variation of activity and sulfurresistance of the catalysts. NiClPd catalysts had a higher resistance to deactivation by sulfur poisoning. This was associated to a higher concentration of Pd η+ Cl x O y species that would prevent the adsorption of thiophene by both steric and electronic effects. It could also be due to the lower concentration of Pd 0 and Ni 0 on these catalysts, as compared to those shown by the PdNiCl catalysts. Both the Pd 0 and Ni 0 species are more prone to poisoning because of their higher electronic availability.

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Intermetallic Compounds in Catalysis

Armbrüster

2011

Encyclopedia of Catalysis

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In catalysis, intermetallic compounds play an important role as precursors for skeletal catalysts or can be formed under reaction conditions and influence the catalytic properties significantly. They can also be applied as catalysts in an unsupported state in a large number of reactions. Intermetallic compounds are structurally more complex than elemental metals or substitutional alloys and thus offer a broad range of different crystal and electronic structures. In addition, the often partly covalent bonding in the compounds increases their stability under reaction conditions and enables an innovative realization of geometric and electronic concepts. This article summarizes the work in the field, aiming at presenting the different ideas and not at giving a full literature review. Special emphasis is put on the knowledge‐based development, which becomes feasible using unsupported and in situ stable intermetallic compounds as catalysts.

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Palladium, Palladium–Tin, and Palladium–Silver Catalysts in the Selective Hydrogenation of Hexadienes: TPR, Mössbauer, and Infrared Studies of Adsorbed CO

Cited by 66 publications

References 24 publications

Water Denitration over a Pd–Sn/Al2O3 Catalyst

Water Denitration over a Pd–Sn/Al2O3 Catalyst

MORE ACTIVE AND SULFUR RESISTANT BIMETALLIC Pd-NI CATALYSTS

Intermetallic Compounds in Catalysis

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