A theoretical explanation of the effect of oxygen poisoning on industrial Haber-Bosch catalysts

Brian A. Rohr, Aayush R. Singh, Jens K. Nørskov*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

The Haber-Bosch process has been studied extensively, yet a low-temperature, low-pressure process remains elusive. As has been shown many times, this stems in part from the difficulty of breaking the N-N triple bond. In this work, we highlight an additional reason for the lack of a low-temperature ammonia synthesis process: the effect of oxygen poisoning at low temperature. Using density functional theory (DFT), we have created a new model for the active site of industrial Haber-Bosch catalysts which explicitly includes the potassium promoter. Furthermore, we present a new micro-kinetic model for ammonia synthesis that includes the effect of oxygen poisoning due to trace water content in the input gas stream. Our model agrees well with previous experiments and shows that devising a strategy to avoid oxygen poisoning is crucial to creating a low-temperature Haber-Bosch process. Additionally, the model suggests that using a weaker-binding catalyst is one way to avoid oxygen poisoning if it is impractical to remove all water from the reactor.

Original languageEnglish
JournalJournal of Catalysis
Volume372
Pages (from-to)33-38
Number of pages6
ISSN0021-9517
DOIs
Publication statusPublished - 2019

Keywords

  • Alkali promotion
  • Ammonia
  • Catalyst poisoning
  • Density functional theory
  • Haber-Bosch
  • Kinetic modeling

Cite this

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title = "A theoretical explanation of the effect of oxygen poisoning on industrial Haber-Bosch catalysts",
abstract = "The Haber-Bosch process has been studied extensively, yet a low-temperature, low-pressure process remains elusive. As has been shown many times, this stems in part from the difficulty of breaking the N-N triple bond. In this work, we highlight an additional reason for the lack of a low-temperature ammonia synthesis process: the effect of oxygen poisoning at low temperature. Using density functional theory (DFT), we have created a new model for the active site of industrial Haber-Bosch catalysts which explicitly includes the potassium promoter. Furthermore, we present a new micro-kinetic model for ammonia synthesis that includes the effect of oxygen poisoning due to trace water content in the input gas stream. Our model agrees well with previous experiments and shows that devising a strategy to avoid oxygen poisoning is crucial to creating a low-temperature Haber-Bosch process. Additionally, the model suggests that using a weaker-binding catalyst is one way to avoid oxygen poisoning if it is impractical to remove all water from the reactor.",
keywords = "Alkali promotion, Ammonia, Catalyst poisoning, Density functional theory, Haber-Bosch, Kinetic modeling",
author = "Rohr, {Brian A.} and Singh, {Aayush R.} and N{\o}rskov, {Jens K.}",
year = "2019",
doi = "10.1016/j.jcat.2019.01.042",
language = "English",
volume = "372",
pages = "33--38",
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A theoretical explanation of the effect of oxygen poisoning on industrial Haber-Bosch catalysts. / Rohr, Brian A.; Singh, Aayush R.; Nørskov, Jens K.

In: Journal of Catalysis, Vol. 372, 2019, p. 33-38.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - A theoretical explanation of the effect of oxygen poisoning on industrial Haber-Bosch catalysts

AU - Rohr, Brian A.

AU - Singh, Aayush R.

AU - Nørskov, Jens K.

PY - 2019

Y1 - 2019

N2 - The Haber-Bosch process has been studied extensively, yet a low-temperature, low-pressure process remains elusive. As has been shown many times, this stems in part from the difficulty of breaking the N-N triple bond. In this work, we highlight an additional reason for the lack of a low-temperature ammonia synthesis process: the effect of oxygen poisoning at low temperature. Using density functional theory (DFT), we have created a new model for the active site of industrial Haber-Bosch catalysts which explicitly includes the potassium promoter. Furthermore, we present a new micro-kinetic model for ammonia synthesis that includes the effect of oxygen poisoning due to trace water content in the input gas stream. Our model agrees well with previous experiments and shows that devising a strategy to avoid oxygen poisoning is crucial to creating a low-temperature Haber-Bosch process. Additionally, the model suggests that using a weaker-binding catalyst is one way to avoid oxygen poisoning if it is impractical to remove all water from the reactor.

AB - The Haber-Bosch process has been studied extensively, yet a low-temperature, low-pressure process remains elusive. As has been shown many times, this stems in part from the difficulty of breaking the N-N triple bond. In this work, we highlight an additional reason for the lack of a low-temperature ammonia synthesis process: the effect of oxygen poisoning at low temperature. Using density functional theory (DFT), we have created a new model for the active site of industrial Haber-Bosch catalysts which explicitly includes the potassium promoter. Furthermore, we present a new micro-kinetic model for ammonia synthesis that includes the effect of oxygen poisoning due to trace water content in the input gas stream. Our model agrees well with previous experiments and shows that devising a strategy to avoid oxygen poisoning is crucial to creating a low-temperature Haber-Bosch process. Additionally, the model suggests that using a weaker-binding catalyst is one way to avoid oxygen poisoning if it is impractical to remove all water from the reactor.

KW - Alkali promotion

KW - Ammonia

KW - Catalyst poisoning

KW - Density functional theory

KW - Haber-Bosch

KW - Kinetic modeling

U2 - 10.1016/j.jcat.2019.01.042

DO - 10.1016/j.jcat.2019.01.042

M3 - Journal article

VL - 372

SP - 33

EP - 38

JO - Journal of Catalysis

JF - Journal of Catalysis

SN - 0021-9517

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