Surface characterisation of Pd?Ag/Al2O3 catalysts for acetylene hydrogenation using an improved XPS procedure

Lamb, Robert N.; Ngamsom, Bongkot; Trimm, D.L.; Gong, Bin; Silveston, P. L.; Praserthdam, Piyasan

doi:10.1016/j.apcata.2004.03.041

Cited by 83 publications

(33 citation statements)

References 21 publications

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“…Figure 3a shows the spectra of Pd/BC and Pd/C electrocatalysts. Pd 3d region exhibits a doublet at binding energies of ~ 335.7 assigned to Pd 3d 5\2 and 340.9 assigned to Pd 3d 3\2 with a spin-orbit splitting of about ~ 5.2 eV, in agreement with the literature [49][50][51] and the tails on the left side of each peak suggest the presence of oxide palladium with metallic palladium on both samples. The components located at ~ 335.3, ~ 336.2 and ~ 337.3-336.6 eV and attributed to metallic Pd, Pd(II) and Pd(IV) phases, respectively [52,53].…”

Section: Resultssupporting

confidence: 88%

Palladium nanoparticles supported on mesoporous biocarbon from coconut shell for ethanol electro-oxidation in alkaline media

Ferreira

Cavallari

Bergamaschi

et al. 2018

Mater Renew Sustain Energy

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Palladium nanoparticles supported on carbon Vulcan XC72 (Pd/C) and biocarbon (Pd/BC) synthesized by sodium borohydride process were used as catalysts for ethanol electro-oxidation in alkaline media. The biocarbon (BC) from coconut shell with mesoporous and high surface area (792 m 2 g −1) was obtained by carbonization at 900 °C and the hydrothermal treatment in a microwave oven. The D-band and G-band intensity ratio (I D /I G) from Raman analysis showed high disorder of the biocarbon, while X-ray photoelectron spectroscopy (XPS) suggests higher percentage of oxygen groups on the surface of biocarbon than of Vulcan XC72. From X-ray diffraction (XRD), it was observed peaks in 2θ degree related to the face centered cubic (fcc) structure of palladium and the mean crystallite sizes calculated based on the diffraction peak of Pd (220) were 5.6 nm for Pd/C and 5.3 nm for Pd/BC. Using Transmission Electron Microscope (TEM), it was observed particles well dispersed on both carbons support materials. The electrocatalytic activity of the materials was investigated by cyclic voltammetry (CV) and chronoamperometry (CA) experiments. The peak current density (on CV experiments) from ethanol electro-oxidation on Pd/BC was 50% higher than on Pd/C, while the current density measured at 15 min of CA experiments was 80% higher on Pd/BC than on Pd/C. The higher catalytic activity of Pd/BC might be related to the large surface area of the biocarbon (792 m 2 g −1) vs (239 m 2 g −1) of Vulcan carbon, the defects of the biocarbon structure and higher amount of oxygen on the surface than Carbon Vulcan XC 72.

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Section: Resultssupporting

confidence: 88%

Palladium nanoparticles supported on mesoporous biocarbon from coconut shell for ethanol electro-oxidation in alkaline media

Ferreira

Cavallari

Bergamaschi

et al. 2018

Mater Renew Sustain Energy

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“…According to the electrostatic model, it results from the higher electronegativity of Pd vs. Ag and corresponds to an electronic enrichment of the metallic Pd. This is in agreement with the work of Lamb et al 67 and with the observation of partial charge transfer from Ag to Pd 68,69 .…”

Section: Xps Surface Investigation Of the Catalystssupporting

confidence: 93%

“…This behavior was not observed in the case of bimetallic catalysts. The absence of negative reduction peak could be related to the presence of smaller Pd particles 62,63 or this behavior may be connected with the presence of chlorine ions adsorbed on the catalysts surface, as formation of the hydride depends as well on the nature of the Pd support interface. 64 For all Ag-Pd catalysts two reduction ranges were identified.…”

Section: Tpr Analysis Of the Catalystsmentioning

confidence: 99%

Understanding the influence of the composition of the Ag Pd catalysts on the selective formic acid decomposition and subsequent levulinic acid hydrogenation

Sneka-Płatek

Kaźmierczak

Jędrzejczyk

et al. 2020

International Journal of Hydrogen Energy

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Formic acid is obtained in equimolar amount with levulinic acid during the hydrolysis of cellulose and thus can be used as a sustainable hydrogen source in the direct levulinic acid hydrogenation towards gamma-valerolactone (biofuel additive). Ag-Pd catalysts prepared by various methods and containing different Ag:Pd ratio were investigated in this context. By combining activity tests, characterization of the main physicochemical properties of the catalysts and DFT study of formic acid decomposition, the key factors responsible for the activity of Ag-Pd catalysts in both the formic acid decomposition and the subsequent hydrogenation of levulinic acid were specified. Pd is shown to be active, but prone to poisoning by CO, while the CO poisoning remains limited on diluted Ag-Pd alloy with strong intermetallic interaction, where its adsorption is very weak thanks to the isolation of Pd atoms.Therefore, the catalyst containing 4%Ag-1%Pd/AlOOH showed the highest selectivity in formic acid decomposition as well as the highest activity in levulinic acid hydrogenation (34% conversion in 5 h at 190°C).

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“…In case of composites (Figure 2(e), 3(e) and 4(e)) the binding energy of Ag 3d 5/2 (367.51 to 367.65 eV) slightly deviates which may probably be due to some interactions between ZIF‐11 and AgNPs surface facing to the imido group of ZIF‐11. [ 51 ] Zn 2p expanded XPS spectrum of ZIF‐11 (Figure S6(b)) has two major and sharp peaks at 1045.0 eV and 1021.8 eV attributable to 2p 1/2 and 2p 3/2 , respectively. Zn 2p expanded XPS spectra of composites AZ1, AZ2 and AZ3 are given in Figure 2(b), 3(b) and 4(b), respectively, and the corresponding binding energies (1044.1–1044.7 eV and 1021.0–1021.5 eV) are given in Table ST2.…”

Section: Resultsmentioning

confidence: 99%

Facile Synthesis of Metal–Organic Framework (ZIF‐11) and Ag NPs Encapsulated‐ZIF‐11 Composite as an Effective Heterogeneous Catalyst for Photodegradation of Methylene Blue

Chandra

Nath

2020

Applied Organom Chemis

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Facile synthesis of metal–organic framework based on zeolitic imidazolate (ZIF‐11) has been optimized to get a material with rho topology. For the first time AgNPs in various dosing amounts (using 150, 300 and 500 μL of its suspension in methanol) have been successfully encapsulated within ZIF‐11 matrix at room temperature using binary solvent (methanol and toluene) yielding novel multi‐core‐shell AgNPs@ZIF‐11 (AZ1, AZ2 and AZ3) composites. Encapsulation of AgNPs (particle size: 11.76 ± 2.3 nm) has been confirmed by TEM and ultraviolet diffuse reflectance spectroscopic (UV‐DRS) analysis. The lowering of band gap of ZIF‐11 from 4.36 to 4.21 eV indicates the micro‐environment of AgNPs within ZIF‐11 framework, which has also been ensured by XPS analysis. ZIF‐11 and AgNPs@ZIF‐11 composites are highly stable up to 500 °C under air and N2 atmosphere. It has been found that AZ1 composite exhibits excellent photocatalytic activity (almost 100% degradation) toward MB (1.6 mg/L) at pH ≥ 8. Further, various factors such as loading amount of AgNPs (150, 300 and 500 μL suspension in methanol), amount of catalysts (5 mg, 10 mg and 15 mg) and concentration (1.6 mg L−1, 3.19 mg L−1 and 6.38 mg L−1) of methylene blue (MB) dye during photodegradation experiments have been investigated. The capacious achievement of AZ1 composite is its reusability and recyclability; it can be reutilized up to three cycles with the same efficiency (100%) while under fourth and fifth cycle, it can degrade off 92.12% and 72.75% MB, respectively. AgNPs may act as a mediator to promote the quick transfer of photo‐induced electrons and electron–hole pairs separation in ZIF‐11. This work opens a new type of easily fabricated core‐shell composites utilizing ZIF‐11 for wastewater remediation process.

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Surface characterisation of Pd?Ag/Al2O3 catalysts for acetylene hydrogenation using an improved XPS procedure

Cited by 83 publications

References 21 publications

Palladium nanoparticles supported on mesoporous biocarbon from coconut shell for ethanol electro-oxidation in alkaline media

Palladium nanoparticles supported on mesoporous biocarbon from coconut shell for ethanol electro-oxidation in alkaline media

Understanding the influence of the composition of the Ag Pd catalysts on the selective formic acid decomposition and subsequent levulinic acid hydrogenation

Facile Synthesis of Metal–Organic Framework (ZIF‐11) and Ag NPs Encapsulated‐ZIF‐11 Composite as an Effective Heterogeneous Catalyst for Photodegradation of Methylene Blue

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