Adsorption of palladium-ammino-aquo complexes on {gamma}-alumina and silica

Journal Article · Mon Feb 01 04:00:00 EST 1993 · Langmuir

DOI:https://doi.org/10.1021/la00026a017· OSTI ID:171444

Spielbauer, D; Zeilinger, H; Knoezinger, H ^[1]

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1. Universitaet Muenchen (Germany)

The adsorption of palladium-ammino-aquo complexes on {gamma}-Al{sub 2}O{sub 3} and SiO{sub 2} from aqueous solution was investigated. The adsorption was carried out under equilibrium conditions and the resulting materials were characterized by laser Raman and UV-vis diffuse reflectance spectroscopy. The experimental data were simulated using the triple layer model (TLM) of Davis in an attempt to elucidate the adsorption mechanism. The TLM, which was developed for the description of the oxide/solution interface, was modified by a further subdivision of the {beta}-layer so as to allow adsorption of ions having largely different radii, such as Pd(NH{sub 3}){sub 4}{sup 2+} and NH{sub 4}{sup +}. The palladium-ammino-aquo complexes are adsorbed on both oxides with or without exchange of ligands depending on the adsorption conditions, such as pH, nature of the base, and nature of the electrolyte. Adsorption at high pH ({gamma}-Al{sub 2}O{sub 3}, >10.6, SiO{sub 2}, >10.0) from an aqueous solution of NH{sub 3} leads predominantly to electrostatically adsorbed Pd(NH{sub 3}){sub 4}{sup 2+}, whereas adsorption at lower pH and/or using of an aqueous NaOH solution also promotes reactions involving ligand exchange leading to species such as Pd(NH{sub 3}){sub 3}(SOH){sup 2+} (S indicates surface). 16 refs., 11 figs., 4 tabs.

• Sponsoring Organization: USDOE
• OSTI ID: 171444
• Journal Information: Langmuir, Journal Name: Langmuir Journal Issue: 2 Vol. 9; ISSN LANGD5; ISSN 0743-7463
• Country of Publication: United States
• Language: English

Related Subjects

10 SYNTHETIC FUELS
40 CHEMISTRY
ADSORPTION
ALUMINIUM OXIDES
CARBON MONOXIDE
CATALYSTS
FUEL CELLS
HYDROGENATION
MATHEMATICAL MODELS
METHANOL
PALLADIUM COMPLEXES
SILICA
SOLUTIONS
SPECTROSCOPY