In Situ Redispersion of Platinum Autoexhaust Catalysts: An On‐Line Approach to Increasing Catalyst Lifetimes?

Abstract

Dedicated to the Catalysis Society of Japan on the occasion of its 50th Anniversary Supported precious metals, such as platinum (Pt), rhodium (Rh), and palladium (Pd), are used to facilitate many industrial catalytic processes. Pt in particular is found at the core of catalysts used throughout the petrochemical industry: from bifunctional catalysts (isomerization/dehydrogenation) used for refining of hydrocarbon fuel stocks, to three-way (CO and hydrocarbon oxidation/NO x reduction) conversions within car exhausts. In this latter, ubiquitous applicationcommercialized in the USA and Japan in 1977 [1] -Pt has always been a pivotal component in the abatement of harmful gas emissions from gasoline-or diesel-driven engines. The ever-increasing appreciation of the damage that noxious gas emissions are doing to our environment and the finite availability of noble metals provide strong drivers for the continued study and optimization of the behavior of Pt-based three-way catalysts (TWCs). Central to technological progress in this area is a fundamental understanding of how these materials behave, which may allow us to stop them degrading or deactivating during operation.

Metal Redispersion Strategies for Recycling of Supported Metal Catalysts: A Perspective

“…88 It was determined that the larger the initial particle size, then the slower the re-dispersion process, in agreement with Monte Carlo simulations. 49 The effect of temperature on the rate of re-dispersion was also investigated.…”

“…49 The effect of temperature on the rate of re-dispersion was also investigated. 88 Unsurprisingly, the re-dispersion occurs faster at higher temperatures, indicating an activated process, a fact which is reinforced considering no re-dispersion occurred at 400 °C or below. Additionally, it was found that re-dispersion occurred much faster at higher oxygen concentrations, which supports the theory that Pt oxide interactions with the support are important to the redispersion process.…”

<i>In Situ</i> and Simultaneous Observation of Palladium Redox and Oxygen Storage/Release in Pd/Sr&ndash;Fe&ndash;O Perovskite Catalysts Using Dispersive XAFS

“…12) These results strongly suggest that the dynamics of the structural changes of the metal ions are closely related to the oxygen storage/release process in TWCs, although little direct experimental observation has been reported.…”

Oxide-based nanomaterials for fuel cell catalysis: the interplay between supported single Pt atoms and particles

“…It was proposed that the formation of such bonds drives the redispersion of Pt particles into smaller clusters. 155 These studies 154,155 suggested the formation of a monolayer of oxidized Pt on the surface of a ceria-based material after treatment in an oxygen atmosphere. Based on the binding energy of the corresponding species in Pt 4f spectra, we speculate that the species described in that work are similar to Pt 2+ species anchored at {100} facets described above.…”