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Roen, Stine; Norby, Truls; Strandbakke, Ragnar & Polfus, Jonathan M.
(2023).
Electrochemical characterization of Ba0.95La0.05(Fe0.7Ni0.2Zn0.1)O3-δ for proton ceramic electrochemical cells.
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Gudmundsdottir, Jonina Björg; Vøllestad, Einar; Haugsrud, Reidar & Polfus, Jonathan
(2023).
Oxygen Exchange Kinetics of BaGd0.3La0.7Co2O6-d.
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Ewerhardt, Patrick; Wu, Mengxin; Norby, Truls; Bjørheim, Tor Svendsen & Polfus, Jonathan M.
(2023).
Finite element modelling of kinetic processes in proton ceramic electrochemical cells.
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Småbråten, Didrik Rene & Polfus, Jonathan
(2023).
DFT on electrodes for high-temperature electrolysis.
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Småbråten, Didrik Rene; Polfus, Jonathan; Strandbakke, Ragnar; Singh, Kalpana; Veenstra, Peter & Fontaine, Marie-Laure
(2023).
DFT modelling of thermodynamic and kinetic parameters in electrochemical proton ceramic conducting cells.
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Gudmundsdottir, Jonina Björg; Thoreton, Vincent; Vøllestad, Einar & Polfus, Jonathan
(2022).
Oxygen Exchange Kinetics of BaGd0.3La0.7Co2O6-d Steam Electrodes for Proton Ceramic Electrochemical Cells.
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Kim, Donghoi; Liu, Zhongxuan; Anantharaman, Rahul; Riboldi, Luca; Odsæter, Lars Hov & Berstad, David Olsson
[Vis alle 10 forfattere av denne artikkelen]
(2022).
Design of a novel hybrid clean hydrogen production process with membrane assisted CO2 capture through liquefaction.
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Talic, Belma; Dayaghi, Amir Masoud; Vøllestad, Einar; Stefan, Elena; Sunding, Martin Fleissner & Polfus, Jonathan
(2022).
Chemical Stability of Proton Conducting BaZr1-xCexO3-Based Electrolytes in Pressurized CO2-Containing Atmospheres.
Vis sammendrag
Acceptor doped barium cerates and zirconates are attractive electrolyte materials for use in various proton ceramic electrochemical devices such as fuel cells and hydrogen pumps. However, the long-term durability of these materials may be challenged by poor chemical stability in CO2-containing atmospheres.
In this work, the chemical stability of the electrolyte material BaZr0.8Ce0.1Y0.1O3 (BZCY81) is studied in CO2 and CO2-H2. Dense pellets prepared by sintering with NiO as a sintering aid were exposed to up to 10 bar CO2(-H2) for up to 150 h at elevated temperatures (400-800°C). After exposure, the pellet surface was analyzed by grazing incidence X-ray diffraction (XRD), scanning electrode microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) to search for BaCO3 formation. Overall, the electrolyte material displayed excellent stability towards CO2. A small increase in apparent BaCO3 concentration on the pellet surface was only detected by XPS for samples aged in CO2 and CO2-H2 at 800 °C. However, BaCO3 was not visible by XRD and SEM-EDS, indicating that the reactivity is limited to a nm-thick region of the electrolyte surface. The impact of processing conditions such as sintering temperature and use of NiO sintering aid on the electrolyte stability will be discussed.
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Polfus, Jonathan; Småbråten, Didrik Rene & Liu, Xin
(2022).
Linking Atomistic and Electrochemical Modelling of Proton Ceramic Electrochemical Cells.
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Dayaghi, Amir Masoud; Polfus, Jonathan; Strandbakke, Ragnar; Vøllestad, Einar; Haugsrud, Reidar & Norby, Truls
(2022).
Effects of NiO, ZnO and CuO sintering additives on the hydration of BaZr0.4Ce0.4(Y,Yb)0.2O3-δ proton conducting electrolytes.
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Liu, Zhongxuan; Kim, Donghoi; Polfus, Jonathan Marc; Peters, Thijs & Anantharaman, Rahul
(2020).
Membrane-Assisted CO2 capture through liquefaction for clean H2 production.
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Benthem Muñiz, Marta; Ali, Ayaz; Polfus, Jonathan & Belle, Branson
(2019).
2D crystal temperature dependent adhesion in the development of Van der Waals heterostructures .
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Polfus, Jonathan M.; Yang, Jing & Yildiz, Bilge
(2019).
Correction: Interplay between H<inf>2</inf>O and CO<inf>2</inf> coadsorption and space-charge on Y-doped BaZrO<inf>3</inf> surfaces(Journal of Materials Chemistry A (2018) 6 (24823-24830) DOI: 10.1039/C8TA09491H).
Journal of Materials Chemistry A.
ISSN 2050-7488.
7(35),
s. 20438–20439.
doi:
10.1039/c9ta90210d.
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Dahl-Hansen, Runar Plunnecke; Akkopru-Akgun, Betul; Vøllestad, Einar; Polfus, Jonathan M.; Denis, L & Coleman, K
[Vis alle 9 forfattere av denne artikkelen]
(2019).
Degradation of PZT in humid ambient – an electrochemically controlled process.
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Dahl-Hansen, Runar Plunnecke; Akkopru-Akgun, Betul; Denis, Lyndsey; Coleman, Kathleen; Polfus, Jonathan M. & Vøllestad, Einar
[Vis alle 9 forfattere av denne artikkelen]
(2019).
PiezoMEMS reliability: why the electrode-material matters in humid ambient.
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Li, Zuoan; Xing, Wen; Polfus, Jonathan M.; Denonville, Christelle; Fontaine, Marie-Laure & Bredesen, Rune
(2018).
Ceramic-based composite membranes for gas separation.
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Belle, Branson; Xing, Wen; Stange, Marit Synnøve Sæverud; S. Azar, Amin; Sunding, Martin Fleissner & Polfus, Jonathan M.
(2018).
Scalable MoS2 growth via Mo sputtering and post H2S treatment.
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Norby, Truls Eivind; Min, Chen; Bondevik, Tarjei & Polfus, Jonathan M.
(2018).
Space Charge Layers and Their Role for Properties of Interfaces in Solid State Ionics.
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Fleischer, Christian; Polfus, Jonathan M.; Bjørheim, Tor Svendsen & Norby, Truls Eivind
(2018).
Defect Chemistry of Few- and Monolayer MoS2.
Vis sammendrag
Defect chemistry has given the possibility to control and tune properties to obtain better functional bulk materials. In comparison, and despite the recent interest and prospects of two-dimensional materials, their defect chemistry remains mainly unexplored. We believe that an understanding of the influence of the dielectric environment on the defect chemistry and properties is crucial for further developing new and superior 2D materials. Here, we present results for molybdenum disulphide (MoS2) films on Si/SiO2 substrates. Methods comprise magnetron sputtering of Mo with subsequent annealing in H2S atmosphere and the chemical vapour transport method. The films and defects are characterised by AFM, XPS, photoluminescence, optical microscopy and Raman spectroscopy in addition to electrical measurements in controlled atmospheres. Ab initio computations on a variety of point defects and defect clusters further elucidate the defect chemistry.
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Polfus, Jonathan M. & Malerød-Fjeld, Harald
(2018).
Protonic Membrane Reforming of Natural Gas to Hydrogen with Carbon Capture.
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Polfus, Jonathan M.; Yang, Jing; Tuller, Harry; Yildiz, Bilge & Bredesen, Rune
(2018).
Coadsorption of H2O and CO2 on BaZrO3-based proton-conducting electrolytes.
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Polfus, Jonathan M.; Yang, Jing; Tuller, Harry; Yildiz, Bilge & Bredesen, Rune
(2018).
Interplay between H2O/CO2 coadsorption and space-charge on Y-doped BaZrO3 surfaces.
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Li, Zuoan; Fontaine, Marie-Laure; Xing, Wen; Denonville, Christelle; Polfus, Jonathan M. & Henriksen, Partow Pakdel
[Vis alle 7 forfattere av denne artikkelen]
(2017).
Novel molten/solid composite oxygen transport membranes for CO2 capture.
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Li, Zuoan; Fontaine, Marie-Laure; Denonville, Christelle; Xing, Wen; Polfus, Jonathan M. & Henriksen, Partow Pakdel
[Vis alle 7 forfattere av denne artikkelen]
(2017).
Designing rules for enhancing surface kinetics in functional oxides for clean energy technologies.
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Chen, Min; Lozano, Helena Téllez; Druce, John; Matsumoto, Hiroshige; Sazinas, Rokas & Polfus, Jonathan M.
[Vis alle 7 forfattere av denne artikkelen]
(2017).
Surface chemistry of BaZr0.9Y0.1O3-δ and its effect on the electrochemical properties of a Ni/BaZr0.9Y0.1O3-δ interface for proton ceramic electrochemical cells.
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Pishahang, Mehdi & Polfus, Jonathan M.
(2017).
Defect Chemistry in Grain Boundaries of Proton
Conducting BaCeO3.
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Li, Zuoan; Fontaine, Marie-Laure; Polfus, Jonathan M.; Denonville, Christelle; Xing, Wen & Henriksen, Partow Pakdel
[Vis alle 7 forfattere av denne artikkelen]
(2016).
Fabrication and performance of asymmetric tubular H2 membranes based on LWM-LSC composites.
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Fontaine, Marie-Laure; Xing, Wen; Bredesen, Rune; Denonville, Christelle; Polfus, Jonathan M. & Strandbakke, Ragnar
[Vis alle 10 forfattere av denne artikkelen]
(2016).
Proton conducting electrolysers with tubular segmented-in-series cells for hydrogen production.
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Henriksen, Partow Pakdel & Polfus, Jonathan M.
(2016).
Naturgass kan gi grønt hydrogen.
Dagens næringsliv.
ISSN 0803-9372.
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Fontaine, Marie-Laure; Vøllestad, Einar; Polfus, Jonathan M.; Denonville, Christelle; Xing, Wen & Li, Zuoan
[Vis alle 8 forfattere av denne artikkelen]
(2016).
Proton Conducting Electrolysers with Tubular Segmented-in-series Cells for Hydrogen Production.
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Grandcolas, Mathieu; Sahoo, Prangya Parimita; Foss, Carl Erik Lie; Xing, Wen; Polfus, Jonathan M. & Sunde, Svein
[Vis alle 8 forfattere av denne artikkelen]
(2016).
Novel photoelectrocatalytic concepts for conversion of nitrogen to fuels and chemicals.
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Polfus, Jonathan M.; Norby, Truls & Bredesen, Rune
(2016).
Proton Conduction Across Interfaces in Y-doped BaZrO3 Investigated by First-Principles Calculations.
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Hasle, Ida Margrete; Haugsrud, Reidar & Polfus, Jonathan M.
(2016).
Computational Studies of Cation Transport in Barium Zirconate.
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Tilset, Bente Gilbu; Rørvik, Per Martin; Larring, Yngve; Fontaine, Marie-Laure & Polfus, Jonathan M.
(2016).
Keramiske membraner for hydrogensamfunnet.
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Fontaine, Marie-Laure; Denonville, Christelle; Polfus, Jonathan M.; xing, wen; Dahl, Paul Inge & Sunde, Tor Olav Løveng
[Vis alle 7 forfattere av denne artikkelen]
(2015).
Development of proton conducting electrolyser cells.
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Sunding, Martin Fleissner; Polfus, Jonathan M.; Zheng, Kun; Svenum, Ingeborg-Helene & Pedersen, Eirik Østbye
(2015).
Analysing reduced transition metal containing compounds with XPS.
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Norby, Truls; Haugsrud, Reidar & Polfus, Jonathan M.
(2015).
Defects and transport in proton conducting BZY.
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Sahoo, Prangya Parimita; Schrade, Matthias; Grandcolas, Mathieu; Polfus, Jonathan M.; Foss, Carl Erik Lie & Sunde, Svein
[Vis alle 7 forfattere av denne artikkelen]
(2015).
Photoelectrocatalytic conversion of water, carbon dioxide, and nitrogen to fuels and chemicals.
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Saeed, Sarmad Waheed; Hancke, Ragnhild & Polfus, Jonathan M.
(2015).
CO2 capture by hydrogen separation membranes.
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Polfus, Jonathan M.
(2015).
First-principles studies of defects and interfaces in perovskite ceramics.
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Polfus, Jonathan M.; Bjørheim, Tor Svendsen; Pishahang, Mehdi; Norby, Truls & Bredesen, Rune
(2015).
Influence of space-charge on the surface defect chemistry of BaZrO3.
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Polfus, Jonathan M.; Li, Zuoan; Sunding, Martin Fleissner; Xing, Wen; Fontaine, Marie-Laure & Henriksen, Partow Pakdel
[Vis alle 7 forfattere av denne artikkelen]
(2015).
Chemical stability of cercer H2 membranes in the La28-xW4+xO54+3x/2-δ–LaCrO3-δ system.
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Maso Carcases, Nahum; Polfus, Jonathan M.; Fontaine, Marie-Laure & Norby, Truls
(2015).
Electrical Properties of Nonstoichiometric BaxZr0.85Y0.15O2.925 Ceramics
Prepared by Solid State Reactive Sintering.
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Norby, Truls & Polfus, Jonathan M.
(2015).
Space Charge Layers and Their Role in Properties of Interfaces in Solid State Ionics.
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Norby, Truls & Polfus, Jonathan M.
(2015).
Grain boundaries in ion conducting ceramics;
theory and practice - properties and applications
.
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Maso Carcases, Nahum; Polfus, Jonathan M.; Fontaine, Marie-Laure & Norby, Truls
(2014).
Electrical properties of undoped and acceptor-Doped (LaO)2SO4 Ceramics.
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Maso Carcases, Nahum; Polfus, Jonathan M.; Fontaine, Marie-Laure & Norby, Truls
(2014).
Electrical properties of nonstoichiometric Ba1+xZr0.85Y0.15O2.925 ceramics prepared by solid state reactive sintering.
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Polfus, Jonathan M.; Xing, Wen; Hanetho, Sidsel Meli; Dahl, Paul Inge; Riktor, Marit Dalseth & Larring, Yngve
[Vis alle 9 forfattere av denne artikkelen]
(2014).
Enhancing the O2 permeability of CaTi0.85Fe0.15O3-δ based membranes by Mn-doping.
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Polfus, Jonathan M.; Xing, Wen; Fontaine, Marie-Laure; Henriksen, Partow Pakdel & Bredesen, Rune
(2014).
Ceramic Composites of Mixed Ionic-Electronic Conductors as Hydrogen Membranes.
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Polfus, Jonathan M.; Xing, Wen; Fontaine, Marie-Laure; Denonville, Christelle; Henriksen, Partow Pakdel & Bredesen, Rune
(2014).
Ceramic Composites of Mixed Ionic-Electronic conductors as Hydrogen Membranes.
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Polfus, Jonathan M.; Fontaine, Marie-Laure; Maso Carcases, Nahum; Magraso, Anna; Pishahang, Mehdi & Norby, Truls
[Vis alle 7 forfattere av denne artikkelen]
(2014).
SIntering Mechanisms and H2S stability of BaZrO3 ceramics with sintering aids for biogas operated fuel cells.
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Fontaine, Marie-Laure; Magrasó, Anna; Polfus, Jonathan M.; Norby, Truls; Dahl, Paul Inge & Pishahang, Mehdi
[Vis alle 7 forfattere av denne artikkelen]
(2014).
Effects of sintering additives on BaZr1-xYxO3-d densification, stability, and proton conductivity.
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Polfus, Jonathan M.
(2013).
Improving performance and manufacturability of high temperature hydrogen transport membranes.
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Fontaine, Marie-Laure; Bredesen, Rune; Dahl, Paul Inge; Denonville, Christelle; Larring, Yngve & Polfus, Jonathan M.
[Vis alle 8 forfattere av denne artikkelen]
(2013).
Development of thin film supported tubular membranes for high temperature gas separation.
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Maso Carcases, Nahum; Polfus, Jonathan M.; Fontaine, Marie-Laure; Pishahang, Mehdi; Bredesen, Rune & Norby, Truls
(2013).
Biogas operated proton ceramic fuel cells with novel S-tolerant functional materials.
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Polfus, Jonathan M. & Norby, Truls
(2013).
Biogas operated proton ceramic fuel cells.
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Polfus, Jonathan M.; Pishahang, Mehdi; Fontaine, Marie-Laure; Norby, Truls & Bredesen, Rune
(2013).
Biogas operated PCFC: Computational and experimental studies of the sulfur tolerance of BaZrO3 and hydration of La2O2S and La2O2SO4.
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Polfus, Jonathan M.; Fontaine, Marie-Laure; Pishahang, Mehdi; Norby, Truls & Bredesen, Rune
(2013).
Biogas operated proton ceramic fuel cells with novel S-tolerant functional materials.
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Gutterød, Emil Sebastian; Haugsrud, Reidar & Polfus, Jonathan M.
(2016).
An Experimental and Computational Study of Nitrogen Activation on Promoted Ruthenium Catalysts.
Universitetet i Oslo.
Vis sammendrag
Ruthenium based catalysts for ammonia synthesis have been studied extensively following
the industrial adoption of a promoted carbon supported ruthenium catalyst in
the Kellogg Advanced Ammonia Process (KAAP). Nevertheless, there are still fundamental
aspects such as the dissociative adsorption of nitrogen—generally regarded
as the rate determining step of NH3 synthesis—and the influence of the barium promoter,
not fully explored. In the present work, the activation of nitrogen on barium
promoted ruthenium is elucidated through a combined experimental and computational
approach.
Nitrogen dissociation and association on a clean and barium promoted Ru(0001)
step were investigated through DFT based calculations using VASP. Unpromoted dissociation
was found to proceed with an energy barrier of 51 kJmol−1, with a N-N
distance of the transition state (TS) of 1.864 Å. The calculated activation barrier for
association was 135 kJmol−1, which increased to 161 kJmol−1 when diffusion of atomic
nitrogen along the terrace was considered. Upon promotion by a unit of atomic Ba,
BaOH and BaO at the step, the dissociation barrier decreased rather similarly by 21,
18 and 18 kJmol−1, respectively. The chemical state of the promoting unit was determined
to have a larger effect on the association barrier, which decreases by 19, 10
and 5 kJmol−1, respectively. A previously not reported local energy minimum state
with one nitrogen atom adsorbed on the b5-hcp site and the other at a step-bridge site
was identified. A significant stabilization of the local minimum state is observed upon
promotion: the N-N distance of the initial and final state of dissociation increased
(which can be associated with a weakening of the N-N bond), while it decreased for
the TS and the local minimum state. The promoting effect decreases rapidly with
increasing distance to the dissociating nitrogen, indicating that the interactions were
of electronic nature.
Powdered catalyst samples of Ru-Ba/AC were prepared by Ba(NO3)2 wet-impregnation
of 5 wt% Ru on activated carbon. The nitrogen isotope exchange (IE) reaction 14,14N2
+ 15,15N2 = 214,15N2 on Ru-Ba/AC was investigated in the temperature range 320–
750°C at N2 pressures of 20–230mbar, by means of gas-phase analysis with mass
spectrometry (GPA-MS). Apparent isotope exchange activation energies in range 162–
178 kJmol−1 were obtained below 425°C. This is in good agreement with the literature
and the present computational results. At higher temperatures the apparent activaiii
Abstract
tion energy abruptly decreases to 64–88 kJmol−1. It is suggested that the change in
temperature dependence is due to limitations by pore diffusion at higher temperatures.
In the presence of 1mbar water vapor in the temperature range 575–625°C, the isotope
exchange rate was significantly reduced compared to under dry conditions, and
the apparent activation energy increased from 88 ± 2 kJmol−1 to 126 ± 12 kJmol−1.
When water vapor was introduced, evolution of H2 was observed, indicating that oxidation
of partially reduced Ba occurred in the presence of H2O. Isotherms of the
isotope exchange rate showed reaction orders with respect to nitrogen partial pressure
of 0.83 ± 0.05 and 0.88 ± 0.03 at 625°C and 700°C, respectively, and 1.1 at 450°C. All
of which are in good agreement with values reported in literature for NH3 synthesis.
Deactivation of the catalyst was observed at temperatures above 500°C, resulting
in a significantly decreasing IE rate with time. In accordance with reports from literature,
and the computational and experimental results, it is proposed the isotope
exchange rate and activation energy are highly dependent on the chemical state of the
barium promoter, which is further dependent on the environmental conditions, such
as temperature and the presence of water vapor.
iv