Effects of four-mode hydrothermal aging on three-way catalysts for passive selective catalytic reduction to control emissions from lean-burn gasoline engine

C. R. Thomas; J. A. Pihl; M. J. Lance; T. J. Toops; J. E. Parks; J. Lauterbach

doi:10.1016/j.apcatb.2018.11.051

Effects of four-mode hydrothermal aging on three-way catalysts for passive selective catalytic reduction to control emissions from lean-burn gasoline engine

C. R. Thomas, J. A. Pihl, M. J. Lance, T. J. Toops, J. E. Parks, J. Lauterbach

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16 Scopus citations

Abstract

Passive selective catalytic reduction (SCR) is a promising approach for the control of NO_X emissions in lean burn gasoline exhausts. It requires ammonia (NH₃) to be produced over a three-way catalyst (TWC) during periods of fuel-rich operation for the reduction of NO_X during periods of fuel-lean operation. Previous research has shown the viability of this system but has not examined the effects of hydrothermal degradation. This work is focused on evaluating the effects of hydrothermal aging on the TWC in a passive SCR system. Two catalysts were studied: a Pd-TWC, and a NO_X storage and reduction (NSR) TWC. Samples were aged at 920 °C for 100 h using a four-mode hydrothermal aging procedure. This causes the catalyst to be oxidized and reduced, as it would in a real system. The effects of aging were evaluated using simulated exhaust under both steady state and lean-rich cycling conditions. Hydrothermal aging caused significant changes in catalyst activity, leading to a decrease in low temperature conversion of carbon monoxide (CO) and propane (C₃H₈) on both catalysts, and degradation of oxygen storage and NO_X storage components. However, the catalysts maintained their activity for NO_X conversion and NH₃ production, showing sufficient activity for the operation of a passive SCR with an optimum projected fuel consumption of 92–98% compared to stoichiometric operation.

Original language	English
Pages (from-to)	284-294
Number of pages	11
Journal	Applied Catalysis B: Environmental
Volume	244
DOIs	https://doi.org/10.1016/j.apcatb.2018.11.051
State	Published - May 5 2019

Funding

Funding was provided by Department of Energy Vehicle Technologies Office and the South Carolina Smartstate Center for Strategic Approaches to the Generation of Electricity (SAGE) at the University of South Carolina . Additionally, a portion of this research was performed using instrumentation (FEI Talos F200X S/TEM) provided by the Department of Energy, Office of Nuclear Energy, Fuel Cycle R&D Program and the Nuclear Science User Facilities. This research was sponsored by the U.S. Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy - Vehicle Technologies Office. This manuscript has been authored by UT-Battelle, LLC, under Contract No. DE-AC0500OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for the United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-access-plan ).

Keywords

Hydrothermal aging
Passive selective catalytic reduction
Three-way catalyst

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10.1016/j.apcatb.2018.11.051

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title = "Effects of four-mode hydrothermal aging on three-way catalysts for passive selective catalytic reduction to control emissions from lean-burn gasoline engine",

abstract = "Passive selective catalytic reduction (SCR) is a promising approach for the control of NOX emissions in lean burn gasoline exhausts. It requires ammonia (NH3) to be produced over a three-way catalyst (TWC) during periods of fuel-rich operation for the reduction of NOX during periods of fuel-lean operation. Previous research has shown the viability of this system but has not examined the effects of hydrothermal degradation. This work is focused on evaluating the effects of hydrothermal aging on the TWC in a passive SCR system. Two catalysts were studied: a Pd-TWC, and a NOX storage and reduction (NSR) TWC. Samples were aged at 920 °C for 100 h using a four-mode hydrothermal aging procedure. This causes the catalyst to be oxidized and reduced, as it would in a real system. The effects of aging were evaluated using simulated exhaust under both steady state and lean-rich cycling conditions. Hydrothermal aging caused significant changes in catalyst activity, leading to a decrease in low temperature conversion of carbon monoxide (CO) and propane (C3H8) on both catalysts, and degradation of oxygen storage and NOX storage components. However, the catalysts maintained their activity for NOX conversion and NH3 production, showing sufficient activity for the operation of a passive SCR with an optimum projected fuel consumption of 92–98% compared to stoichiometric operation.",

keywords = "Hydrothermal aging, Passive selective catalytic reduction, Three-way catalyst",

author = "Thomas, {C. R.} and Pihl, {J. A.} and Lance, {M. J.} and Toops, {T. J.} and Parks, {J. E.} and J. Lauterbach",

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AB - Passive selective catalytic reduction (SCR) is a promising approach for the control of NOX emissions in lean burn gasoline exhausts. It requires ammonia (NH3) to be produced over a three-way catalyst (TWC) during periods of fuel-rich operation for the reduction of NOX during periods of fuel-lean operation. Previous research has shown the viability of this system but has not examined the effects of hydrothermal degradation. This work is focused on evaluating the effects of hydrothermal aging on the TWC in a passive SCR system. Two catalysts were studied: a Pd-TWC, and a NOX storage and reduction (NSR) TWC. Samples were aged at 920 °C for 100 h using a four-mode hydrothermal aging procedure. This causes the catalyst to be oxidized and reduced, as it would in a real system. The effects of aging were evaluated using simulated exhaust under both steady state and lean-rich cycling conditions. Hydrothermal aging caused significant changes in catalyst activity, leading to a decrease in low temperature conversion of carbon monoxide (CO) and propane (C3H8) on both catalysts, and degradation of oxygen storage and NOX storage components. However, the catalysts maintained their activity for NOX conversion and NH3 production, showing sufficient activity for the operation of a passive SCR with an optimum projected fuel consumption of 92–98% compared to stoichiometric operation.

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Effects of four-mode hydrothermal aging on three-way catalysts for passive selective catalytic reduction to control emissions from lean-burn gasoline engine

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