LAPSE:2025.0165
Published Article
LAPSE:2025.0165
A Century of Data: Thermodynamics and Kinetics for Ammonia Synthesis on Various Commercial Iron-based Catalysts
June 27, 2025
Abstract
This work presents an improved thermodynamic model, an equilibrium model, and a unified kinetic model for ammonia synthesis. The thermodynamic model accurately describes the non-ideality of the reaction system up to 1000 bar using a modified Soave-Redlich-Kwong Equation-of-State. The developed Langmuir-Hinshelwood kinetic model accurately describes ammonia synthesis on iron-based catalysts by incorporating N* and H* surface species, whereas H* species are mainly relevant below 400°C. The model fits an extensive dataset across diverse conditions (251-550°C, 1-324 bar, H2/N2 ratios 0.33-8.5, and space velocities of 1-1800 Nm3 kg-cat-1 h-1) and accounts for catalyst activity variations through a Relative Catalytic Activity factor.
This work presents an improved thermodynamic model, an equilibrium model, and a unified kinetic model for ammonia synthesis. The thermodynamic model accurately describes the non-ideality of the reaction system up to 1000 bar using a modified Soave-Redlich-Kwong Equation-of-State. The developed Langmuir-Hinshelwood kinetic model accurately describes ammonia synthesis on iron-based catalysts by incorporating N* and H* surface species, whereas H* species are mainly relevant below 400°C. The model fits an extensive dataset across diverse conditions (251-550°C, 1-324 bar, H2/N2 ratios 0.33-8.5, and space velocities of 1-1800 Nm3 kg-cat-1 h-1) and accounts for catalyst activity variations through a Relative Catalytic Activity factor.
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Keywords
Ammonia, iron catalyst, Steady-state kinetics
Subject
Suggested Citation
Keestra H, Slotboom Y, Rouwenhorst KH, Brilman DW. A Century of Data: Thermodynamics and Kinetics for Ammonia Synthesis on Various Commercial Iron-based Catalysts. Systems and Control Transactions 4:92-97 (2025) https://doi.org/10.69997/sct.128811
Author Affiliations
Keestra H: Sustainable Process Technology, Faculty of Science and Technology, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands; Catalytic Processes & Materials, MESA+ Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE Enschede
Slotboom Y: Sustainable Process Technology, Faculty of Science and Technology, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands
Rouwenhorst KH: Catalytic Processes & Materials, MESA+ Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE Enschede, the Netherlands; Ammonia Energy Association, 77 Sands Street, 6th Floor, Brooklyn, NY 11201, USA
Brilman DW: Sustainable Process Technology, Faculty of Science and Technology, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands
Slotboom Y: Sustainable Process Technology, Faculty of Science and Technology, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands
Rouwenhorst KH: Catalytic Processes & Materials, MESA+ Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE Enschede, the Netherlands; Ammonia Energy Association, 77 Sands Street, 6th Floor, Brooklyn, NY 11201, USA
Brilman DW: Sustainable Process Technology, Faculty of Science and Technology, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands
Journal Name
Systems and Control Transactions
Volume
4
First Page
92
Last Page
97
Year
2025
Publication Date
2025-07-01
Version Comments
Original Submission
Other Meta
PII: 0092-0097-1242-SCT-4-2025, Publication Type: Journal Article
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LAPSE:2025.0165
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https://doi.org/10.69997/sct.128811
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Jun 27, 2025
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