Low temperature water-gas shift: Optimization of K loading on Pt/m-ZrO2 for enhancing CO conversion

Caleb D. Watson; Michela Martinelli; Donald C. Cronauer; A. Jeremy Kropf; Christopher L. Marshall; Gary Jacobs

doi:10.1016/j.apcata.2020.117572

Low temperature water-gas shift: Optimization of K loading on Pt/m-ZrO₂ for enhancing CO conversion

Caleb D. Watson, Michela Martinelli, Donald C. Cronauer, A. Jeremy Kropf, Christopher L. Marshall, Gary Jacobs

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

15 Scopus citations

Abstract

Previous work showed that alkali doping of Pt/ZrO₂ significantly improved the LT-WGS rate. This improvement was caused by an acceleration in the rate of formate decomposition, the rate limiting step of an associative mechanism, through electronically weakening the C–H bond. In this study, the effects that potassium loading on Pt/ZrO₂ have on the rate of LT-WGS and the strength of the C–H bond in intermediate formate species are explored. Catalysts were investigated using in-situ DRIFTS, TPR-MS, TPD, EXAFS, and catalyst testing. Loadings of 1.7 wt.% potassium or higher shifted the formate ν(CH) band to significantly lower wavenumbers, indicating weakening of the bond. For the optimal loading, 2.6 wt.% K, the formate C–H bond was significantly weakened, and the surface of Pt nanoparticles remained largely uncovered. However, loadings of 3.4 wt. % and above blocked the surface of the platinum nanoparticles. This, in addition to an increasing average Pt⁰ cluster size, hindered platinum from assisting in dehydrogenation of formate during steam promoted formate decomposition occurring in LT-WGS.

Original language	English
Article number	117572
Journal	Applied Catalysis A: General
Volume	598
DOIs	https://doi.org/10.1016/j.apcata.2020.117572
State	Published - May 25 2020

Bibliographical note

Publisher Copyright:
© 2020 Elsevier B.V.

Funding

The work carried out at the CAER was supported in part by funding from the Commonwealth of Kentucky . Argonne\u2019s research was supported in part by the U.S. Department of Energy (DOE), Office of Fossil Energy, National Energy Technology Laboratory (NETL) . Advanced Photon Source was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences , under Contract No. DE-AC02-06CH11357 . MRCAT operations are supported by the Department of Energy and the MRCAT member institutions . Caleb D. Watson would like to acknowledge support from the Undergraduate NSF Research Program, supported by the National Science Foundation through grant award # 1832388 . Gary Jacobs would like to thank UTSA and the State of Texas for financial support through startup funds. The work carried out at the CAER was supported in part by funding from the Commonwealth of Kentucky. Argonne's research was supported in part by the U.S. Department of Energy (DOE), Office of Fossil Energy, National Energy Technology Laboratory (NETL). Advanced Photon Source was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. MRCAT operations are supported by the Department of Energy and the MRCAT member institutions. Caleb D. Watson would like to acknowledge support from the Undergraduate NSF Research Program, supported by the National Science Foundation through grant award #1832388. Gary Jacobs would like to thank UTSA and the State of Texas for financial support through startup funds.

Funders	Funder number
Southwest Texas State University
Office of Fossil Energy and Carbon Management
The University of Texas Health Science Center at San Antonio
U.S. Department of Energy Oak Ridge National Laboratory U.S. Department of Energy National Science Foundation National Energy Research Scientific Computing Center
COMMONWEALTH OF KENTUCKY
National Science Foundation Office of International Science and Engineering
National Energy Technology Laboratory
U.S. Department of Energy Chinese Academy of Sciences Guangzhou Municipal Science and Technology Project Oak Ridge National Laboratory Extreme Science and Engineering Discovery Environment National Science Foundation National Energy Research Scientific Computing Center National Natural Science Foundation of China	1832388
DOE Basic Energy Sciences	DE-AC02-06CH11357

Keywords

Associative mechanism
Electronic effect
Formate
Low temperature water-gas shift (LT-WGS)
Platinum (Pt)
Potassium loading
Zirconia (ZrO)

ASJC Scopus subject areas

Catalysis
Process Chemistry and Technology

Access to Document

10.1016/j.apcata.2020.117572

Cite this

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title = "Low temperature water-gas shift: Optimization of K loading on Pt/m-ZrO2 for enhancing CO conversion",

abstract = "Previous work showed that alkali doping of Pt/ZrO2 significantly improved the LT-WGS rate. This improvement was caused by an acceleration in the rate of formate decomposition, the rate limiting step of an associative mechanism, through electronically weakening the C–H bond. In this study, the effects that potassium loading on Pt/ZrO2 have on the rate of LT-WGS and the strength of the C–H bond in intermediate formate species are explored. Catalysts were investigated using in-situ DRIFTS, TPR-MS, TPD, EXAFS, and catalyst testing. Loadings of 1.7 wt.\% potassium or higher shifted the formate ν(CH) band to significantly lower wavenumbers, indicating weakening of the bond. For the optimal loading, 2.6 wt.\% K, the formate C–H bond was significantly weakened, and the surface of Pt nanoparticles remained largely uncovered. However, loadings of 3.4 wt. \% and above blocked the surface of the platinum nanoparticles. This, in addition to an increasing average Pt0 cluster size, hindered platinum from assisting in dehydrogenation of formate during steam promoted formate decomposition occurring in LT-WGS.",

keywords = "Associative mechanism, Electronic effect, Formate, Low temperature water-gas shift (LT-WGS), Platinum (Pt), Potassium loading, Zirconia (ZrO)",

author = "Watson, \{Caleb D.\} and Michela Martinelli and Cronauer, \{Donald C.\} and Kropf, \{A. Jeremy\} and Marshall, \{Christopher L.\} and Gary Jacobs",

note = "Publisher Copyright: {\textcopyright} 2020 Elsevier B.V.",

year = "2020",

month = may,

day = "25",

doi = "10.1016/j.apcata.2020.117572",

language = "English",

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T2 - Optimization of K loading on Pt/m-ZrO2 for enhancing CO conversion

AU - Watson, Caleb D.

AU - Martinelli, Michela

AU - Cronauer, Donald C.

AU - Kropf, A. Jeremy

AU - Marshall, Christopher L.

AU - Jacobs, Gary

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N2 - Previous work showed that alkali doping of Pt/ZrO2 significantly improved the LT-WGS rate. This improvement was caused by an acceleration in the rate of formate decomposition, the rate limiting step of an associative mechanism, through electronically weakening the C–H bond. In this study, the effects that potassium loading on Pt/ZrO2 have on the rate of LT-WGS and the strength of the C–H bond in intermediate formate species are explored. Catalysts were investigated using in-situ DRIFTS, TPR-MS, TPD, EXAFS, and catalyst testing. Loadings of 1.7 wt.% potassium or higher shifted the formate ν(CH) band to significantly lower wavenumbers, indicating weakening of the bond. For the optimal loading, 2.6 wt.% K, the formate C–H bond was significantly weakened, and the surface of Pt nanoparticles remained largely uncovered. However, loadings of 3.4 wt. % and above blocked the surface of the platinum nanoparticles. This, in addition to an increasing average Pt0 cluster size, hindered platinum from assisting in dehydrogenation of formate during steam promoted formate decomposition occurring in LT-WGS.

AB - Previous work showed that alkali doping of Pt/ZrO2 significantly improved the LT-WGS rate. This improvement was caused by an acceleration in the rate of formate decomposition, the rate limiting step of an associative mechanism, through electronically weakening the C–H bond. In this study, the effects that potassium loading on Pt/ZrO2 have on the rate of LT-WGS and the strength of the C–H bond in intermediate formate species are explored. Catalysts were investigated using in-situ DRIFTS, TPR-MS, TPD, EXAFS, and catalyst testing. Loadings of 1.7 wt.% potassium or higher shifted the formate ν(CH) band to significantly lower wavenumbers, indicating weakening of the bond. For the optimal loading, 2.6 wt.% K, the formate C–H bond was significantly weakened, and the surface of Pt nanoparticles remained largely uncovered. However, loadings of 3.4 wt. % and above blocked the surface of the platinum nanoparticles. This, in addition to an increasing average Pt0 cluster size, hindered platinum from assisting in dehydrogenation of formate during steam promoted formate decomposition occurring in LT-WGS.

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