Hydrogen adsorption sites studied by carbon monoxide adsorption to explain the hydrogenation activity of benzene on Pd and Pt catalysts

Chen, Ching-Shiun; Lin, Jarrn-Horng; Chen, Hsiu-Wei

doi:10.1016/j.apcata.2005.09.036

Cited by 23 publications

(5 citation statements)

References 31 publications

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“…On the contrary, benzaldehyde adsorbs only “temporarily” on more open surfaces and defects and desorbs intact. This agrees with the preferential adsorption of acetophenone, the product of 1-phenylethanol oxidation that does not decarbonylate, , on on-top and bridge sites …”

Section: Resultssupporting

confidence: 82%

Discrimination of Active Palladium Sites in Catalytic Liquid-Phase Oxidation of Benzyl Alcohol

et al. 2006

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Knowledge of the structure of active sites is a prerequisite for the rational design of solid catalysts. Using site-selective blocking by CO and isotope labeling combined with in situ attenuated total reflection infrared (ATR-IR) spectroscopy, we were able to discriminate the different sites involved in the liquid-phase oxidation of benzyl alcohol on Pd/Al(2)O(3). The main reaction, that is, the oxidative dehydrogenation of the alcohol to the corresponding aldehyde, showed only little dependence on structure and occurred on all exposed Pd faces, whereas the undesired product decarbonylation occurred preferentially on hollow sites on (111) Pd faces. This explains why specific blocking of the latter sites, as realized in the industrially used Pd-Bi/Al(2)O(3) catalysts, leads to improved catalytic performance.

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Section: Resultssupporting

confidence: 82%

Discrimination of Active Palladium Sites in Catalytic Liquid-Phase Oxidation of Benzyl Alcohol

et al. 2006

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“…DRIFT-IR spectra with CO probes of alumina-supported Pd, Pt, and Pd@Pt NPs with different Pt/Pd ratios are shown in Figure . As shown in Figure a, Pd/Al 2 O 3 exhibits a band at 1946 cm –1 , which is a characteristic band of bridged CO on Pd sites. − The band near 2100 cm –1 for linear CO on Pd sites is not observed for Pd/Al 2 O 3 , which is consistent with the reported spectra of well-faceted Pd NPs . Figure b shows the DRIFT-IR spectrum of alumina-supported Pt NPs.…”

Section: Resultssupporting

confidence: 82%

Kinetically Stabilized Pd@Pt Core–Shell Octahedral Nanoparticles with Thin Pt Layers for Enhanced Catalytic Hydrogenation Performance

Zhang

et al. 2015

ACS Catal.

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This study investigates the structural stability of small Pd@Pt core@shell octahedral nanoparticles (NPs) and their shell thickness dependent catalytic performance for p-chloronitrobenzene hydrogenation with H2. The 6–8 nm Pd@Pt octahedral NPs are prepared by a sequential reduction method, and the characterization results confirm that Pd@Pt octahedral NPs with one to four atomic Pt layers can be controllably synthesized. The Pd@Pt octahedral NPs with one atomic Pt layer demonstrate excellent structural stability with the maintenance of core–shell structures as well as high catalytic stability during cycle to cycle catalytic p-chloronitrobenzene hydrogenation reactions. The alumina-supported Pd@Pt octahedral NPs illustrate a superior catalytic performance relative to individual Pt and Pd and their physical mixtures. Theoretical calculations by density functional theory suggest that the unexpected structural stability for Pd@Pt octahedral NPs with thin Pt shells and their corresponding catalytic stability during hydrogenation reactions can be ascribed to the strong binding between Pt surfaces and reactants/products in catalytic reactions. The enhanced catalytic performance of Pd@Pt octahedral NPs possibly originates from the core–shell interaction, which adjusts the electronic state of surface Pt atoms to be suitable for selective p-chloronitrobenzene hydrogenation.

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“…The DRIFTS measurements of CO adsorption over Pd/Al 2 O 3 and Pd-In/Al 2 O 3 catalysts were carried out to illustrate the structural modification by indium. As shown in Figure , the band at 2050–2150 cm –1 can be assigned to the linear-bonded CO on Pd defect sites such as kinks and corners, and the bands at 1950–2000, 1900–1950, and 1900–1850 cm –1 can be assigned to compressed-bridge-bonded CO, isolated-bridge-bonded CO and 3-fold-hollow-bonded CO on Pd ensemble sites, respectively. ,, The linear on-top and compressed-bridge-bonded CO adsorption was also observed at high CO coverage due to adsorption at a relatively high CO pressure. In comparison with the monometallic Pd sample, the IR spectra of the bimetallic Pd-In (Figure ) show distinct changes in the bridge-bonded region as well as the linear on-top region.…”

Section: Resultsmentioning

confidence: 89%

Selective Hydrogenation of Acetylene over Pd-In/Al₂O₃ Catalyst: Promotional Effect of Indium and Composition-Dependent Performance

et al. 2017

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Highly dispersed bimetallic Pd-In catalysts on Al 2 O 3 were prepared by a simple impregnation method. In comparison with the unsupported intermetallic catalyst, the supported Pd-In catalyst exhibited several magnitudes higher activity and similar selectivity for selective acetylene hydrogenation. Moreover, the activity, selectivity, and anticoking performance of the Pd-In catalyst were superior to those of the monometallic Pd catalyst. The electron transferred from indium weakened the adsorption of ethylene on the negatively charged Pd sites and hence improved the selectivity of Pd-In/Al 2 O 3 . The inhibited formation of hydride due to the presence of indium also contributed to the higher selectivity. The promoted activation of hydrogen, owing to the weak adsorption of acetylene on Pd-In/Al 2 O 3 , and decreased particle size jointly contributed to the enhanced activity of Pd-In/Al 2 O 3 . In addition, green oil formation on Pd-In/Al 2 O 3 was retarded by the presence of indium, contributing to the enhanced stability of the catalyst. The bimetallic Pd-In catalysts showed a strongly composition dependent performance, which resulted from the different extent of electronic and/or geometric modification of Pd active sites.

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Hydrogen adsorption sites studied by carbon monoxide adsorption to explain the hydrogenation activity of benzene on Pd and Pt catalysts

Cited by 23 publications

References 31 publications

Discrimination of Active Palladium Sites in Catalytic Liquid-Phase Oxidation of Benzyl Alcohol

Discrimination of Active Palladium Sites in Catalytic Liquid-Phase Oxidation of Benzyl Alcohol

Kinetically Stabilized Pd@Pt Core–Shell Octahedral Nanoparticles with Thin Pt Layers for Enhanced Catalytic Hydrogenation Performance

Selective Hydrogenation of Acetylene over Pd-In/Al₂O₃ Catalyst: Promotional Effect of Indium and Composition-Dependent Performance

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Hydrogen adsorption sites studied by carbon monoxide adsorption to explain the hydrogenation activity of benzene on Pd and Pt catalysts

Cited by 23 publications

References 31 publications

Discrimination of Active Palladium Sites in Catalytic Liquid-Phase Oxidation of Benzyl Alcohol

Discrimination of Active Palladium Sites in Catalytic Liquid-Phase Oxidation of Benzyl Alcohol

Kinetically Stabilized Pd@Pt Core–Shell Octahedral Nanoparticles with Thin Pt Layers for Enhanced Catalytic Hydrogenation Performance

Selective Hydrogenation of Acetylene over Pd-In/Al2O3 Catalyst: Promotional Effect of Indium and Composition-Dependent Performance

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Selective Hydrogenation of Acetylene over Pd-In/Al₂O₃ Catalyst: Promotional Effect of Indium and Composition-Dependent Performance