On the various Cu-redox pathways and O2-mediated Bronsted-to-Lewis adsorbed-NH3 redistribution under SCR half-cycle conditions

Dhruba J. Deka; Rohil Daya; Saurabh Y. Joshi; William P. Partridge

doi:10.1016/j.apcata.2022.118656

On the various Cu-redox pathways and O₂-mediated Bronsted-to-Lewis adsorbed-NH₃ redistribution under SCR half-cycle conditions

Dhruba J. Deka, Rohil Daya, Saurabh Y. Joshi, William P. Partridge

Applied Catalysis&Emissions Res. Group

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

13 Scopus citations

Abstract

The Standard SCR reaction on Cu-SSZ-13 is a complex redox process facilitated by a reduction half cycle (RHC) and an oxidation half cycle (OHC). It is generally accepted that RHC requires the simultaneous presence of NO and NH₃, while OHC requires both NO and O₂; however understanding of how these individual reactants impact the Cu redox cycle is limited. In this study, we provide experimental investigation of NO-only, NH₃-only and NO+NH₃ RHC, and their relative rates. Simple kinetic models were developed to understand the dependance of NO-only and NH₃-only RHC on Cu speciation. Various OHC routes including NO+O₂ and O₂-only OHC, and a previously unreported H₂O-mediated OHC pathway were also investigated. Detailed NH₃ temperature-programmed desorption studies showed that RHC selectively consumes NH₃ adsorbed on Lewis-acid sites, and that part of the remaining Bronsted-bound NH₃ moves to the Lewis-acid sites during subsequent OHC, thereby resulting in a repartitioning of adsorbed NH₃.

Original language	English
Article number	118656
Journal	Applied Catalysis A: General
Volume	640
DOIs	https://doi.org/10.1016/j.apcata.2022.118656
State	Published - Jun 25 2022

Funding

This research was supported in part by the DOE Office of Energy Efficiency and Renewable Energy (EERE) Vehicle Technologies Office (VTO) and used resources at the National Transportation Research Center, a DOE-EERE User Facility at Oak Ridge National Laboratory. We thank Neal Currier, Aleksey Yezerets and Krishna Kamasamudram from Cummins Inc. for their valuable support and promotion of the CRADA (cooperative research and development agreement) partnership within which this work was performed, and their SCR-catalyst insights. We thank Josh Pihl, group leader of the ORNL Applied Catalysis and Emissions Research Group, for his critical review and suggestions regarding catalysis methods and experiments, and help with experimental system automation. We thank DOE VTO Program & Technology Managers: Gurpreet Singh, Siddiq Khan, and Ken Howden for supporting the CRADA project. This research was supported in part by the DOE Office of Energy Efficiency and Renewable Energy ( EERE ) Vehicle Technologies Office ( VTO ) and used resources at the National Transportation Research Center, a DOE-EERE User Facility at Oak Ridge National Laboratory. We thank Neal Currier, Aleksey Yezerets and Krishna Kamasamudram from Cummins Inc. for their valuable support and promotion of the CRADA (cooperative research and development agreement) partnership within which this work was performed, and their SCR-catalyst insights. We thank Josh Pihl, group leader of the ORNL Applied Catalysis and Emissions Research Group , for his critical review and suggestions regarding catalysis methods and experiments, and help with experimental system automation. We thank DOE VTO Program & Technology Managers: Gurpreet Singh, Siddiq Khan, and Ken Howden for supporting the CRADA project. This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05–00OR22725 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 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 ).

Funders	Funder number
CRADA
DOE VTO
DOE-EERE
U.S. Department of Energy
Office of Energy Efficiency and Renewable Energy
Oak Ridge National Laboratory

Keywords

Cu-SSZ-13
Hydrothermal aging
NH3 temperature-programmed desorption
SCR redox half-cycle
Selective catalytic reduction

Access to Document

10.1016/j.apcata.2022.118656

Cite this

@article{f2efdedbd6fc42bebb3b8ca31eef7f02,

title = "On the various Cu-redox pathways and O2-mediated Bronsted-to-Lewis adsorbed-NH3 redistribution under SCR half-cycle conditions",

abstract = "The Standard SCR reaction on Cu-SSZ-13 is a complex redox process facilitated by a reduction half cycle (RHC) and an oxidation half cycle (OHC). It is generally accepted that RHC requires the simultaneous presence of NO and NH3, while OHC requires both NO and O2; however understanding of how these individual reactants impact the Cu redox cycle is limited. In this study, we provide experimental investigation of NO-only, NH3-only and NO+NH3 RHC, and their relative rates. Simple kinetic models were developed to understand the dependance of NO-only and NH3-only RHC on Cu speciation. Various OHC routes including NO+O2 and O2-only OHC, and a previously unreported H2O-mediated OHC pathway were also investigated. Detailed NH3 temperature-programmed desorption studies showed that RHC selectively consumes NH3 adsorbed on Lewis-acid sites, and that part of the remaining Bronsted-bound NH3 moves to the Lewis-acid sites during subsequent OHC, thereby resulting in a repartitioning of adsorbed NH3.",

keywords = "Cu-SSZ-13, Hydrothermal aging, NH3 temperature-programmed desorption, SCR redox half-cycle, Selective catalytic reduction",

author = "Deka, {Dhruba J.} and Rohil Daya and Joshi, {Saurabh Y.} and Partridge, {William P.}",

note = "Publisher Copyright: {\textcopyright} 2022 Elsevier B.V.",

year = "2022",

month = jun,

day = "25",

doi = "10.1016/j.apcata.2022.118656",

language = "English",

volume = "640",

journal = "Applied Catalysis A: General",

issn = "0926-860X",

publisher = "Elsevier",

}

TY - JOUR

T1 - On the various Cu-redox pathways and O2-mediated Bronsted-to-Lewis adsorbed-NH3 redistribution under SCR half-cycle conditions

AU - Deka, Dhruba J.

AU - Daya, Rohil

AU - Joshi, Saurabh Y.

AU - Partridge, William P.

PY - 2022/6/25

Y1 - 2022/6/25

N2 - The Standard SCR reaction on Cu-SSZ-13 is a complex redox process facilitated by a reduction half cycle (RHC) and an oxidation half cycle (OHC). It is generally accepted that RHC requires the simultaneous presence of NO and NH3, while OHC requires both NO and O2; however understanding of how these individual reactants impact the Cu redox cycle is limited. In this study, we provide experimental investigation of NO-only, NH3-only and NO+NH3 RHC, and their relative rates. Simple kinetic models were developed to understand the dependance of NO-only and NH3-only RHC on Cu speciation. Various OHC routes including NO+O2 and O2-only OHC, and a previously unreported H2O-mediated OHC pathway were also investigated. Detailed NH3 temperature-programmed desorption studies showed that RHC selectively consumes NH3 adsorbed on Lewis-acid sites, and that part of the remaining Bronsted-bound NH3 moves to the Lewis-acid sites during subsequent OHC, thereby resulting in a repartitioning of adsorbed NH3.

AB - The Standard SCR reaction on Cu-SSZ-13 is a complex redox process facilitated by a reduction half cycle (RHC) and an oxidation half cycle (OHC). It is generally accepted that RHC requires the simultaneous presence of NO and NH3, while OHC requires both NO and O2; however understanding of how these individual reactants impact the Cu redox cycle is limited. In this study, we provide experimental investigation of NO-only, NH3-only and NO+NH3 RHC, and their relative rates. Simple kinetic models were developed to understand the dependance of NO-only and NH3-only RHC on Cu speciation. Various OHC routes including NO+O2 and O2-only OHC, and a previously unreported H2O-mediated OHC pathway were also investigated. Detailed NH3 temperature-programmed desorption studies showed that RHC selectively consumes NH3 adsorbed on Lewis-acid sites, and that part of the remaining Bronsted-bound NH3 moves to the Lewis-acid sites during subsequent OHC, thereby resulting in a repartitioning of adsorbed NH3.

KW - Cu-SSZ-13

KW - Hydrothermal aging

KW - NH3 temperature-programmed desorption

KW - SCR redox half-cycle

KW - Selective catalytic reduction

UR - http://www.scopus.com/inward/record.url?scp=85130237586&partnerID=8YFLogxK

U2 - 10.1016/j.apcata.2022.118656

DO - 10.1016/j.apcata.2022.118656

M3 - Article

AN - SCOPUS:85130237586

SN - 0926-860X

VL - 640

JO - Applied Catalysis A: General

JF - Applied Catalysis A: General

M1 - 118656

ER -