Catalytic Reactivity of Hydrogen on Palladium and Nickel Hydride Phases

Palczewska, W.

doi:10.1016/s0360-0564(08)60484-8

Cited by 91 publications

(33 citation statements)

References 50 publications

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“…The amount of hydride that forms decreases with increasing dispersion of palladium in supported catalysts [1]. In contrast to the bulk metal, palladium particles smaller than 2.6 nm have been suggested to not form a hydride phase, even at high hydrogen pressures (P H2 =1 atm and T =298 K) [2]. The hydride has higher mobility than the surface hydrogen and can hydrogenate surface adsorbates upon emerging to the surface [3].…”

mentioning

confidence: 99%

Distinguishing surface adsorbed hydrogen from bulk-dissolved hydrogen in supported Pd nanoparticles using in situ Pd L₃-edge XANES

Tew¹,

Miller²,

Bokhoven³

2009

J. Phys.: Conf. Ser.

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Abstract. In situ X-ray absorption spectroscopy at the Pd L 3 edge was applied to determine the particle size effect on the formation of palladium hydride and on surface hydrogen adsorption at room temperature. Pd L 3 edge XANES spectra allow direct detection of hydride formation via a characteristic spectral feature caused by the formation of a Pd-H anti-bonding state. This feature showed strong particle size dependence. The L 3 edge spectra were reproduced using full multiple scattering analysis and density of states calculations and the contributions of bulkdissolved and surface hydrogen to the XANES spectra could be distinguished. The ratio of hydrogen on the surface versus that in the bulk increased with decreasing particle size, and smaller particles dissolved less hydrogen. IntroductionThe particle size and support effects on catalytic performance are two well-known factors that affect the activity and selectivity of a reaction. For hydrogenation reaction catalyzed by palladium catalysts, the particle size effect can be critical because the formation of palladium hydride is particle size dependent. The amount of hydride that forms decreases with increasing dispersion of palladium in supported catalysts [1]. In contrast to the bulk metal, palladium particles smaller than 2.6 nm have been suggested to not form a hydride phase, even at high hydrogen pressures (P H2 =1 atm and T =298 K) [2]. The hydride has higher mobility than the surface hydrogen and can hydrogenate surface adsorbates upon emerging to the surface [3]. Thus, the amount of bulk-dissolved hydrogen seriously affects the activity and selectivity of structure-sensitive hydrogenation reactions [4].Geometrical and electronic information of palladium nano-particles and of palladium hydride can be obtained from X-ray absorption spectroscopy (XAS) at the K and L edges [5,6]. At the Pd K edge XAS, the formation of palladium hydrides was generally deduced from an increased interatomic distance in EXAFS analysis [5]. In contrast, Pd L 3 edge XANES allows the direct detection of palladium hydride via a signature peak at ~6 eV above the Fermi level, caused by the formation of a Pd-H anti-bonding state [6]. This ~6 eV peak can be theoretically simulated [7]. Distinction of bulkdissolved hydrogen from surface hydrogen in a palladium-catalyzed process remains challenging. It was recently reported that nuclear reaction analysis can distinguish surface adsorbed and bulkdissolved hydrogen on or in palladium nanocrystals on Al 2 O 3 NiAl (110) [8]. We performed XAS at the Pd L 3 edge to determine the electronic structural changes that occur in supported nano-sized

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confidence: 99%

Distinguishing surface adsorbed hydrogen from bulk-dissolved hydrogen in supported Pd nanoparticles using in situ Pd L₃-edge XANES

Tew¹,

Miller²,

Bokhoven³

2009

J. Phys.: Conf. Ser.

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“…We found this behavior puzzling initially but now surmise that the sorption phenomena has merely swamped homogeneous dissolution [3]. Whether the sorption is physical or chemical in nature, it would readily account for the apparently aberrant experimental observations and this was the starting point of the research reported here.…”

Section: Introductionmentioning

confidence: 64%

“…The possible benefits to processors are significant, as it may prove in the longer term that any material which enhances hydrogen solubility, from red mud to carbon black to more expensive catalysts, might work equally effectively, if equivalent "surface areas" and desorption behavior are employed. For the case of hydrogen sorption on palladium and nickel [3], the Ni and Pd surfaces saturate at ~ 0.6 atoms of hydrogen/atom of Pd or Ni. At room temperature this occurs at ~ 1 kPa, at 300 C ~ 1 MPa, at 400 C ~ 10 MPa.…”

Section: Introductionmentioning

confidence: 99%

The Impact of Trace Additives on the Apparent Solubility of Hydrogen in Heavy Oil and Related Feedstocks at Low and High Temperatures

Abedi¹

2002

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“…Based on the literature data and our earlier experience concerning the formation and decomposition of β-PdH phase [15,[18][19][20][21][22][23][24], the position, shape (width, distortion), and intensity of a TPHD peak depend on different variables, among which Pd dispersion, type of support, and modifying additives play a dominant role. The introduction of gold to the palladium lattice brings about a more-or-less serious decrease in hydrogen dissolution (i.e., a lower H/Pd ratio in respective hydride phase).…”

Section: Resultsmentioning

confidence: 99%

Influence of microwave activation on the catalytic behavior of Pd-Au/C catalysts employed in the hydrodechlorination of tetrachloromethane

Bonarowska

Zieliński

Matus

et al. 2018

Reac Kinet Mech Cat

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This work investigates the influence of activation by microwave irradiation on the catalytic properties of Pd-Au/C Sibunit catalysts in the hydrodechlorination of CCl 4 . Pd and Pd-Au samples were thoroughly characterized by CO chemisorption, X-ray diffraction, TPHD and STEM, and used in gas phase hydrodechlorination of tetrachloromethane. The studies showed that homogenous Pd-Au alloys are formed more efficiently if short-time microwave activation is applied instead of conventional activation by H 2 reduction at 380°C. These catalysts show higher activity, stability and higher selectivity towards the desired products (C1-C5 hydrocarbons) than the catalysts activated by conventional reduction in 10%H 2 /Ar flow.

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Catalytic Reactivity of Hydrogen on Palladium and Nickel Hydride Phases

Cited by 91 publications

References 50 publications

Distinguishing surface adsorbed hydrogen from bulk-dissolved hydrogen in supported Pd nanoparticles using in situ Pd L₃-edge XANES

Distinguishing surface adsorbed hydrogen from bulk-dissolved hydrogen in supported Pd nanoparticles using in situ Pd L₃-edge XANES

The Impact of Trace Additives on the Apparent Solubility of Hydrogen in Heavy Oil and Related Feedstocks at Low and High Temperatures

Influence of microwave activation on the catalytic behavior of Pd-Au/C catalysts employed in the hydrodechlorination of tetrachloromethane

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Catalytic Reactivity of Hydrogen on Palladium and Nickel Hydride Phases

Cited by 91 publications

References 50 publications

Distinguishing surface adsorbed hydrogen from bulk-dissolved hydrogen in supported Pd nanoparticles using in situ Pd L3-edge XANES

Distinguishing surface adsorbed hydrogen from bulk-dissolved hydrogen in supported Pd nanoparticles using in situ Pd L3-edge XANES

The Impact of Trace Additives on the Apparent Solubility of Hydrogen in Heavy Oil and Related Feedstocks at Low and High Temperatures

Influence of microwave activation on the catalytic behavior of Pd-Au/C catalysts employed in the hydrodechlorination of tetrachloromethane

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Distinguishing surface adsorbed hydrogen from bulk-dissolved hydrogen in supported Pd nanoparticles using in situ Pd L₃-edge XANES

Distinguishing surface adsorbed hydrogen from bulk-dissolved hydrogen in supported Pd nanoparticles using in situ Pd L₃-edge XANES