Ceria in automotive exhaust catalysts: I. Oxygen storage

In many heterogeneous catalysts, the interaction of metal particles with their oxide support can alter the electronic properties of the metal and can play a critical role in determining particle morphology and maintaining dispersion. We used a combination of ultrahigh magnetic field, solid-state magic-angle spinning nuclear magnetic resonance spectroscopy, and high-angle annular dark-field scanning transmission electron microscopy coupled with density functional theory calculations to reveal the nature of anchoring sites of a catalytically active phase of platinum on the surface of a γ-Al 2 O 3 catalyst support material. The results obtained show that coordinatively unsaturated pentacoordinate Al 3+ (Al 3+ penta ) centers present on the (100) facets of the γ-Al 2 O 3 surface are anchoring Pt. At low loadings, the active catalytic phase is atomically dispersed on the support surface (Pt/Al 3+ penta = 1), whereas two-dimensional Pt rafts form at higher coverages.

https://science.sciencemag.org/content/sci/325/5948/1670.full.pdf

Coordinatively Unsaturated Al3+ Centers as Binding Sites for Active Catalyst Phases of Platinum on γ-Al2O3

This review article deals with recent progress in the preparation of sulfated zirconia (SZ)-bassed, strong solid-acid catalysts, the characterization of their physicochemical properties and the evaluation of their catalytic performance in various promising applications. Strong emphasis was put on discussion of controversial issues such as the strength of acid sites, the nature of active sites, the reaction mechanism, and the role and state of supported platinum. An important part of this work was devoted to recent catalytic applications.

Sulfated Zirconia-Based Strong Solid-Acid Catalysts: Recent Progress

Structure sensitivity of methane oxidation over platinum and palladium

Publisher Summary The forms of active components present in heterogeneous catalysts are of importance to catalysis A supported catalyst usually consists of an active component dispersed on a support with a highly specific surface An active component dispersed on a support may end up in one of three forms: (1) it may retain its chemical identity as a separate crystalline or amorphous phase, (2) it may form a new stoichiometric compound with the support or additive, or (3) it may dissolve in the support to give a solid solution This chapter provides a review of various aspects of the phenomenon of spontaneous monolayer dispersion, its nature, effects, and applications Spontaneous monolayer dispersion of compounds on supports is a widespread phenomenon and displays many unique effects The principles involved have applications not only to heterogeneous catalysis, but also to materials science and other related fields

H Plummerjr

Papers

Surface interactions in the Pt/-AlO system