Alumina Over-coating on Pd Nanoparticle Catalysts by Atomic Layer Deposition: Enhanced Stability and Reactivity

Feng, Hao; Lu, Junling; Stair, Peter C.; Elam, Jeffrey W.

doi:10.1007/s10562-011-0548-8

Cited by 166 publications

(215 citation statements)

References 29 publications

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“…Previous studies reported that Pd metal sintering was prominent at high temperature (≥800 °C), and was a major contributor to Pd catalyst deactivation [1][2][3][4]. Upon aging at 1050 °C, metal sintering occurred for both of our Pd catalysts.…”

Section: Aging-induced Pd Sintering: the Primary Catalyst Deactivatiomentioning

confidence: 59%

Part II: Oxidative Thermal Aging of Pd/Al2O3 and Pd/CexOy-ZrO2 in Automotive Three Way Catalysts: The Effects of Fuel Shutoff and Attempted Fuel Rich Regeneration

2015

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Abstract:The Pd component in the automotive three way catalyst (TWC) experiences deactivation during fuel shutoff, a process employed by automobile companies for enhancing fuel economy when the vehicle is coasting downhill. The process exposes the TWC to a severe oxidative aging environment with the flow of hot (800 °C-1050 °C) air. Simulated fuel shutoff aging at 1050 °C leads to Pd metal sintering, the main cause of irreversible deactivation of 3% Pd/Al2O3 and 3% Pd/CexOy-ZrO2 (CZO) as model catalysts. The effect on the Rh component was presented in our companion paper Part I. Moderate support sintering and Pd-CexOy interactions were also experienced upon aging, but had a minimal effect on the catalyst activity losses. Cooling in air, following aging, was not able to reverse the metallic Pd sintering by re-dispersing to PdO. Unlike the aged Rh-TWCs (Part I), reduction via in situ steam reforming (SR) of exhaust HCs was not effective in reversing the deactivation of aged Pd/Al2O3, but did show a slight recovery of the Pd activity when CZO was the carrier. The Pd couples in Pd/CZO are reported to promote the catalytic SR by improving the redox efficiency during the regeneration, while no such promoting effect was observed for Pd/Al2O3. A suggestion is made for improving the catalyst performance. OPEN ACCESSCatalysts 2015, 5 1798 Keywords: automotive three way catalysts (TWC); Pd/Al2O3; Pd/CexOy-ZrO2; fuel shutoff aging; catalyst deactivation; fuel rich regeneration; metal sintering; metal-support interaction

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Section: Aging-induced Pd Sintering: the Primary Catalyst Deactivatiomentioning

confidence: 59%

Part II: Oxidative Thermal Aging of Pd/Al2O3 and Pd/CexOy-ZrO2 in Automotive Three Way Catalysts: The Effects of Fuel Shutoff and Attempted Fuel Rich Regeneration

2015

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“…A viscous-flow ALD reactor (Elam et al, 2002) operating at reduced pressure (120-270 Pa) has also been used by researchers in Argonne National Laboratory for ALD Cronauer et al, 2011;Feng et al, 2010;Feng et al, 2011;Hakim et al, 2005;Hakim et al, 2006;King et al, 2007;Lei et al, 2012;Sereda et al, 2012) ) have been effectively coated, at faster saturation exposure times (on the min-scale). Only small batches (up to 1 g) of materials have been processed in this viscous-flow reactor type.…”

Section: Reactor Technologymentioning

confidence: 99%

Scalable Production of Nanostructured Particles using Atomic Layer Deposition

Goulas

Ommen

2014

KONA

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Core-shell nanoparticles and other nanostructured particles have high potential in applications such as heterogeneous catalysis and energy conversion and storage. However, a hurdle in their utilization is that typically, large amounts of such nanostructured materials are required. Gas-phase coating using atomic layer deposition (ALD, a variant of chemical vapour deposition) can be used to provide the surface of a particle with either an ultrathin continuous coating or a decoration of nanoclusters. When carried out in a fluidized bed, ALD is an attractive way of producing nanostructured particles with excellent scale-up potential. We demonstrate the fabrication of catalysts by deposition of the active phase (Pt) on fluidized nanoparticles (TiO 2 P25) at atmospheric pressure. We show that ALD is a technique that 1) guarantees efficient use of the precursor; 2) allows precise control of the size and loading; 3) can be used for low and medium loading of catalysts by adjusting the number of repeated cycles; 4) leads to high-quality (low impurities level) end-products.

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“…15). 40 The reason for this behavior was revealed through infrared spectroscopic measurements of adsorbed CO designed to probe the Pd surface. These measurements showed that the ALD Al 2 O 3 over-coats preferentially nucleate at Pd corners, steps, and edges while leaving the catalytically active Pd (111) facets accessible for methanol conversion.…”

Section: Stabilization Of Noble Metal Nanoparticlesmentioning

confidence: 99%

Atomic Layer Deposition of Noble Metals – New Developments in Nanostructured Catalysts

Lu¹,

Yu²,

Elam³

2012

Noble Metals

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Alumina Over-coating on Pd Nanoparticle Catalysts by Atomic Layer Deposition: Enhanced Stability and Reactivity

Cited by 166 publications

References 29 publications

Part II: Oxidative Thermal Aging of Pd/Al2O3 and Pd/CexOy-ZrO2 in Automotive Three Way Catalysts: The Effects of Fuel Shutoff and Attempted Fuel Rich Regeneration

Part II: Oxidative Thermal Aging of Pd/Al2O3 and Pd/CexOy-ZrO2 in Automotive Three Way Catalysts: The Effects of Fuel Shutoff and Attempted Fuel Rich Regeneration

Scalable Production of Nanostructured Particles using Atomic Layer Deposition

Atomic Layer Deposition of Noble Metals – New Developments in Nanostructured Catalysts

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