The effects of SO2 exposure on three-way catalysts for passive SCR operation

Calvin Thomas; Josh Pihl; Vitaly Prikhodko; James Parks; Jochen Lauterbach; Todd Toops

doi:10.1016/j.apcata.2022.118771

The effects of SO₂ exposure on three-way catalysts for passive SCR operation

Calvin Thomas, Josh Pihl, Vitaly Prikhodko, James Parks, Jochen Lauterbach, Todd Toops

Research output: Contribution to journal › Article › peer-review

3 Scopus citations

Abstract

Efficient lean-burn gasoline engines cannot employ traditional three-way catalysts (TWCs) to control NO_X emissions due to excess oxygen. Passive selective catalytic reduction (pSCR) is a process designed to control NOx by generating NH₃ over the TWC during fuel-rich operation, storing it on a downstream SCR, and then converting NOx during fuel-lean operation. This work is focused on studying sulfur effects on this promising strategy. Two hydrothermally-aged commercial catalysts were studied for their effectiveness in the presence of SO₂: a Pd-based TWC and a TWC with NO_X storage. The sulfated samples were evaluated in a flow reactor under pSCR conditions and with targeted reactions. SO₂ inhibited the water gas shift and steam reforming reactions, decreasing (but not eliminating) NH₃ production; however, initial activity is recoverable after a simple thermal treatment at 650 °C. This work will prove valuable in understanding, mitigating, and even reversing the effects of SO₂ inhibition on real pSCR systems.

Original language	English
Article number	118771
Journal	Applied Catalysis A: General
Volume	643
DOIs	https://doi.org/10.1016/j.apcata.2022.118771
State	Published - Aug 5 2022

Funding

Funding was provided by the U.S. Department of Energy’s Vehicle Technologies Office ( VTO ). The authors greatly appreciate support from Ken Howden, Siddiq Khan, and Gurpreet Singh at VTO. Funding was provided by the U.S. Department of Energy's Vehicle Technologies Office (VTO). The authors greatly appreciate support from Ken Howden, Siddiq Khan, and Gurpreet Singh at VTO. This manuscript has been authored by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE 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 ).

Funders	Funder number
Ken Howden
Siddiq Khan
U.S. Department of Energy
Vehicle Technologies Office

Keywords

Ammonia (NH)
Generation
Lean-burn gasoline emissions control
Passive SCR
Sulfur
Three-way catalysts (TWC)

Access to Document

10.1016/j.apcata.2022.118771

Cite this

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title = "The effects of SO2 exposure on three-way catalysts for passive SCR operation",

abstract = "Efficient lean-burn gasoline engines cannot employ traditional three-way catalysts (TWCs) to control NOX emissions due to excess oxygen. Passive selective catalytic reduction (pSCR) is a process designed to control NOx by generating NH3 over the TWC during fuel-rich operation, storing it on a downstream SCR, and then converting NOx during fuel-lean operation. This work is focused on studying sulfur effects on this promising strategy. Two hydrothermally-aged commercial catalysts were studied for their effectiveness in the presence of SO2: a Pd-based TWC and a TWC with NOX storage. The sulfated samples were evaluated in a flow reactor under pSCR conditions and with targeted reactions. SO2 inhibited the water gas shift and steam reforming reactions, decreasing (but not eliminating) NH3 production; however, initial activity is recoverable after a simple thermal treatment at 650 °C. This work will prove valuable in understanding, mitigating, and even reversing the effects of SO2 inhibition on real pSCR systems.",

keywords = "Ammonia (NH), Generation, Lean-burn gasoline emissions control, Passive SCR, Sulfur, Three-way catalysts (TWC)",

author = "Calvin Thomas and Josh Pihl and Vitaly Prikhodko and James Parks and Jochen Lauterbach and Todd Toops",

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AU - Thomas, Calvin

AU - Pihl, Josh

AU - Prikhodko, Vitaly

AU - Parks, James

AU - Lauterbach, Jochen

AU - Toops, Todd

PY - 2022/8/5

Y1 - 2022/8/5

N2 - Efficient lean-burn gasoline engines cannot employ traditional three-way catalysts (TWCs) to control NOX emissions due to excess oxygen. Passive selective catalytic reduction (pSCR) is a process designed to control NOx by generating NH3 over the TWC during fuel-rich operation, storing it on a downstream SCR, and then converting NOx during fuel-lean operation. This work is focused on studying sulfur effects on this promising strategy. Two hydrothermally-aged commercial catalysts were studied for their effectiveness in the presence of SO2: a Pd-based TWC and a TWC with NOX storage. The sulfated samples were evaluated in a flow reactor under pSCR conditions and with targeted reactions. SO2 inhibited the water gas shift and steam reforming reactions, decreasing (but not eliminating) NH3 production; however, initial activity is recoverable after a simple thermal treatment at 650 °C. This work will prove valuable in understanding, mitigating, and even reversing the effects of SO2 inhibition on real pSCR systems.

AB - Efficient lean-burn gasoline engines cannot employ traditional three-way catalysts (TWCs) to control NOX emissions due to excess oxygen. Passive selective catalytic reduction (pSCR) is a process designed to control NOx by generating NH3 over the TWC during fuel-rich operation, storing it on a downstream SCR, and then converting NOx during fuel-lean operation. This work is focused on studying sulfur effects on this promising strategy. Two hydrothermally-aged commercial catalysts were studied for their effectiveness in the presence of SO2: a Pd-based TWC and a TWC with NOX storage. The sulfated samples were evaluated in a flow reactor under pSCR conditions and with targeted reactions. SO2 inhibited the water gas shift and steam reforming reactions, decreasing (but not eliminating) NH3 production; however, initial activity is recoverable after a simple thermal treatment at 650 °C. This work will prove valuable in understanding, mitigating, and even reversing the effects of SO2 inhibition on real pSCR systems.

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