Publications

Patkowski W, Zybert M, Ulkowska U, Ronduda H, Bulejak W, Lemańska M, Albrecht A, Moszyński D, Fidler A, Dłużewski P, Raróg-Pilecka W., Influence of lanthanide oxide supports on the performance of barium-promoted cobalt catalysts for ammonia synthesis, „Catalysis Today”, 2026, t.463, s. 1–12.

DOI:
https://doi.org/10.1016/j.cattod.2025.115611.

Abstract

Developing efficient ammonia synthesis catalysts is key to reducing energy consumption and improving sustainability. This study explores barium-promoted cobalt catalysts supported on lanthanide oxides (La₂O₃, Nd₂O₃, Sm₂O₃, Eu₂O₃, Gd₂O₃) to understand how support choice influences catalytic performance. The catalysts were characterised using techniques such as X-ray powder diffraction (XRPD), high-resolution transmission electron microscopy (HRTEM), and temperature-programmed desorption (H₂-TPD, CO₂-TPD). Testing under industrially relevant conditions (400–470°C, 6.3 MPa, H₂/N₂ = 3) revealed that lanthanide oxides strongly affect catalysts’ activity, reducibility, and hydrogen adsorption. Among the tested catalysts, the La₂O₃-supported system exhibited the highest ammonia synthesis activity, likely due to its favorable hydrogen sorption properties and larger active phase surface area available for hydrogen (31 m²·g_Co⁻¹). These findings highlight the potential of lanthanide oxides as supports and the importance of barium as a promoter in cobalt-based catalysts for ammonia synthesis.

Highlights

• Lanthanide oxides as supports influence catalyst activity in ammonia synthesis.
• Ba-Co/La₂O₃ shows highest activity due to H₂ activation and larger active area.
• Support type impacts Co reducibility, H₂ adsorption, and active site formation.

Keywords

Ammonia synthesis; Barium promotion; Cobalt catalysts; Lanthanide oxides

Ronduda H., Lemańska M., Patkowski W., Ostrowski A., Sobczak K., i Raróg-Pilecka W., Role of the active metal (Fe, Co and Ni) on the activity of Nd₂O₃-supported catalysts for ammonia synthesis, „Catalysis Today”, 2026, t.461, s. 1–11.

DOI:
https://doi.org/10.1016/j.cattod.2025.115535

Abstract

Nd₂O₃-supported Fe, Co, and Ni monometallic catalysts were synthesised and used in the ammonia synthesis reaction. The effect of active metal on the physicochemical and catalytic properties was investigated using, e.g., TPR, TPD, XRD, and STEM. The results showed that the kind of active metal used is the factor determining the catalytic activity in ammonia synthesis. The highest ammonia formation rate was exhibited by Co/Nd₂O₃, whereas the highest intrinsic reaction rate (reflected as the TOF value) was shown by Fe/Nd₂O₃. Ni/Nd₂O₃ showed almost no activity in ammonia synthesis. The high ammonia formation rate observed for Co/Nd₂O₃ was attributable to the well-distributed Co nanoparticles (NPs) on the Nd₂O₃ support. The Co NPs were less prone to sintering than Fe NPs under reaction conditions. Thus, although showing lower TOF than Fe NPs, the better distribution of Co NPs resulted in an improved ammonia formation rate. These findings highlight the importance of rational catalyst design for improving ammonia synthesis efficiency.

Highlights

• Nd₂O₃-supported Fe, Co, and Ni monometallic catalysts for NH₃ synthesis.
• Superior NH₃ synthesis performance of the Fe/Nd₂O₃ and Co/Nd₂O₃ catalysts.
• Excellent resistance to sintering of Co and Ni nanoparticles.

Keywords

Ammonia synthesis; Supported catalysts; Iron; Cobalt; Nickel

Ronduda H., Lemańska M., Ulkowska U., Patkowski W., Ostrowski A., Sobczak K., i Raróg-Pilecka W., Enhanced ammonia synthesis over barium cerate-supported cobalt catalyst by rare-earth element doping, „Catalysis Today”, 2025, t.456, s. 1–10.

DOI:
https://doi.org/10.1016/j.cattod.2025.115342

Abstract

A series of BaCeO₃ doped with various rare-earth elements (REE = Nd, Sm, Gd) were synthesised and used as the supports for cobalt catalysts for ammonia synthesis. The effects of rare-earth dopant type and concentration on the physicochemical properties and catalytic activities were studied using, e.g., XRD, STEM-EDX, and TPD techniques. Catalyst testing revealed that the optimal doping concentration was 10 mol%, regardless of the rare-earth ion. Samarium was identified as the most effective dopant, followed by gadolinium and neodymium. The superior performance of the Co/BaCe_0.9REE_0.1O_3–δ catalysts was due to the incorporation of REE dopant into the BaCeO₃ structure, which increased the electron density, enabling efficient electron transfer from the support to the Co surface. This, in turn, facilitated the N₂ dissociative adsorption, recognised as the rate-determining step (RDS) of ammonia synthesis. In addition, the catalysts were characterised by favourable hydrogen adsorption properties (co-existence of weak and strong adsorption sites), contributing to the effective hydrogen activation under the reaction conditions. This study provides an effective approach for designing cobalt catalysts supported on perovskites, demonstrating their great potential as next-generation catalysts for ammonia synthesis.

Highlights

• Co catalysts supported on REE-doped BaCeO3 (REE = Nd, Sm, Gd) for NH3 synthesis.
• Tuneable acid-base properties of BaCeO3 supports by REE doping strategy.
• Strong influence of support basicity on catalyst performance.
• Superior performance of Co supported on BaCe0.9Sm0.1O3–δ catalyst.

Keywords

Ammonia synthesis; Cobalt catalysts; Perovskite supports; Doping; Rare-earth elements

Ronduda H., Zybert M., Patkowski W., Lemańska M., Ostrowski A., Sobczak K., i Raróg-Pilecka W., Understanding the role of caesium additive in cobalt catalysts for ammonia synthesis, „Journal of Thermal Analysis and Calorimetry”, 2025.

DOI:
https://doi.org/10.1007/s10973-025-14354-x

Abstract

Ammonia (NH₃) is the second most produced chemical globally and is one of the largest chemical industries by volume. However, although being well-established, it requires high temperature and pressure conditions, which result in a large energy consumption and carbon dioxide emissions. To address this issue, the development of novel catalysts with high activity under mild reaction conditions has become a prominent area of research. Although the effect of Cs as the promoter for Fe and Ru catalysts has been well described, the effect of Cs doping on the Co catalyst performance in ammonia synthesis has not been well studied yet. Here, we studied the effect of Cs doping on the physicochemical properties and activity of the Co catalysts. It was found that caesium doping was detrimental to the catalytic activity. The ammonia synthesis rate decreased with the increasing amount of caesium added. The Cs species were not thermally stable and evaporated from the surface of the catalysts during the reductive activation. In addition, the Cs doping contributed to the catalyst sintering, resulting in the irreversible loss of active sites. This was the primary reason for the observed poor activity of the Cs-doped Co catalysts in ammonia synthesis.

Keywords

Ammonia; Ammonia synthesis; Catalyst; Cobalt catalyst; Caesium

Patkowski W., Zybert M., Ronduda H., Albrecht A., Moszyński D., Fidler A., Dłużewski P., Mierzwa B., i Raróg-Pilecka W., Toward green ammonia synthesis – exploring the influence of lanthanide oxides as supports on the cobalt catalysts properties, „Journal of CO₂ Utilization”, 2024, t.80, s. 1–13.

DOI:
https://doi.org/10.1016/j.jcou.2024.102699\

Abstract

Nowadays, ammonia is viewed as the prospective green hydrogen fuel carrier. Yet, there still is a demand for active, energy-efficient NH₃ synthesis catalysts to make ammonia use economically viable. This paper studies and discusses lanthanide oxide-supported cobalt catalysts for low-pressure ammonia synthesis, which are intended to be a model for prototyping systems alternative to ruthenium-based catalysts. In the Co/Ln₂O₃ system, lanthanide oxide is a support and an electronic promoter. The electron density on the active phase’s surface is increased through Strong Metal-Support Interactions and the formation of oxygen-deficient, Ln₂O_3−x species capable of electron donation. In the systems, electronic promotion strength depends on the Ln³⁺ cation and the support conductivity, catalyst Turnover Frequency and basicity increase exponentially with the increase of the Ln³⁺ ionic radius. These dependencies enable the design of novel cobalt catalysts of specific properties and outline the prospects for their further development.

Highlights

• Ammonia synthesis cobalt catalysts deposited on lanthanide oxides were synthesised.
• Lanthanide oxide supports act as electronic promoters of the metallic active phase.
• In Co/Ln₂O₃ systems Ln₂O_3−x strong electron-donating sites are formed due to SMSI.
• Promotion influence of Ln₂O₃ depends on the ionic radius of the Ln³⁺ cation.
• Growth of Ln³⁺ radius causes an exponential increase of catalyst TOF and basicity.

Keywords

Ammonia synthesis; Cobalt; Lanthanide oxide; SMSI; Electronic promotion

Ronduda H., Młotek M., Góral W., Zybert M., Ostrowski A., Sobczak K., Krawczyk K., i Raróg-Pilecka W., Cobalt catalysts for COx-free hydrogen production: Effect of catalyst type on ammonia decomposition in gliding discharge plasma reactor, „Journal of CO₂ Utilization”, 2024, t.82, s. 1–12.

DOI:
https://doi.org/10.1016/j.jcou.2024.102755

Abstract

Hydrogen is considered the cleanest, most environmentally friendly fuel and energy carrier required for the gradual decarbonisation of many industrial sectors. Using ammonia as a Co_x-free source of hydrogen is the most reasonable and most applicable method. This paper studies the properties and activity of cobalt catalysts in the ammonia decomposition reaction using a plasma-catalytic system. The effect of catalyst type (supported versus bulk) was evaluated. The catalysts were examined using XRD, STEM-EDX, and sorption techniques (N₂ physisorption, TGA-TPR, H₂-TPD, CO₂-TPD) to reveal the influence of physicochemical properties of these two types of catalysts on the efficiency of NH₃ decomposition in the plasma-catalytic process using a gliding discharge plasma. The results disclose that the supported-type catalyst (Ba-Co/CeO2) decomposed NH₃ more effectively than the bulk-type catalyst (Co/Ce/Ba). At discharge power of 300 W and flow rate of 180 dm3 h–1 of NH₃:N₂ mixture (50/50 vol%), the ammonia conversion over the Ba-Co/CeO2 catalyst was 70%, whereas over the Co/Ce/Ba catalyst it was only 21%. The favourable performance of the supported-type catalyst was attributed to a more thermally stable surface area compared with the bulk-type catalyst. Smaller and more stable cobalt nanoparticles (NPs) with numerous weak hydrogen adsorption sites were also seen. Meanwhile, the strong basic sites were generated, improving the electron-donating ability of the surface active sites. High ammonia conversion and relatively low-energy consumption of the plasma-catalytic ammonia decomposition over Ba-Co/CeO₂ make it suitable for practical hydrogen production applications, such as fuel cells and hydrogen storage.

Highlights

• Supported and bulk cobalt catalysts were synthesised and tested in NH₃ decomposition using gliding discharge plasma.
• Supported catalyst decomposed ammonia more effectively than bulk catalyst.
• High performance of supported catalyst was ascribed to thermal stability, favourable H₂ adsorption, and strong basicity.
• NH₃ conversion over supported catalyst achieved 96% with energy consumption of 3.9 kWh m^–3 H₂ at 500 W discharge power.

Keywords

Ammonia; Ammonia decomposition; Plasma-catalyst interactions; Catalyst; Cobalt catalyst

Ronduda H., Zybert M., Patkowski W., Ostrowski A., Sobczak K., Moszyński D., i Raróg-Pilecka W., Elucidating the role of potassium addition on the surface chemistry and catalytic properties of cobalt catalysts for ammonia synthesis, „RSC Advances”, 2024, t.14, s. 23095–23108.

DOI:
https://doi.org/10.1039/d4ra04517c

Abstract

The ammonia synthesis process produces millions of tons of ammonia annually needed for the production of fertilisers, making it the second most produced chemical worldwide. Although this process has been optimised extensively, it still consumes large amounts of energy (around 2% of global energy consumption), making it essential to improve its efficiency. To accelerate this improvement, research on catalysts is necessary. Here, we studied the role of potassium in ammonia synthesis on cobalt catalysts and found that it was detrimental to the catalytic activity. It was shown that, regardless of the amount of introduced K, the activity of the K-modified catalysts was much lower than that of the undoped catalyst. K was found to be in the form of oxide; however, it was unstable and reducible to metallic K, which easily volatilised from the catalyst surface under activation conditions. In addition, potassium doping resulted in the sintering of the catalyst, the decrease in the surface basicity, and contributed to the loss of the active sites, mainly due to the coverage of Co surface by residual K species. K-doped cobalt catalysts for ammonia synthesis: the location, state and effect of potassium dopant on the surface chemistry and catalytic properties.

Zybert M., Ronduda H., Patkowski W., Ostrowski A., Sobczak K., i Raróg-Pilecka W., Improving the catalytic performance of Co/BaCeO₃ catalyst for ammonia synthesis by Y-modification of the perovskite-type support, „RSC Advances”, 2024, t.14, s. 36281–36294.

DOI:
https://doi.org/10.1039/d4ra06251e

Abstract

Y-modified perovskite-type oxides BaCe_1−xY_xO_3−δ (x = 0–0.30) were synthesised and used as supports for cobalt catalysts. The influence of yttrium content on the properties of the support and catalyst performance in the ammonia synthesis reaction was examined using PXRD, STEM-EDX, and sorption techniques (N₂ physisorption, H₂-TPD, CO₂-TPD). The studies revealed that the incorporation of a small amount of yttrium into barium cerate (up to 10 mol%) increased specific surface area and basicity. The catalyst testing under conditions close to the industrial ones (T = 400–470°C, p = 6.3 MPa, H₂/N₂ = 3) showed that the most active catalyst was deposited on a support containing 10 mol% Y. The NH₃ synthesis reaction rate was 15–20% higher than that of the undoped Co/BaCeO₃ catalyst. The activity of the catalysts decreased with further increasing Y content in the support (up to 30 mol%). However, all the studied Co/BaCe_1−xY_xO_3−δ catalysts exhibited excellent thermal stability, over 240 h of operation. The particularly beneficial properties of the catalyst containing 10 mol% of Y were associated with the highest basicity of the support surface, favourable adsorption properties (suitable proportion of weakly and strongly hydrogen-binding sites), and preferred size of cobalt particles (60 nm). The Co/BaCe_0.90Y_0.10O_3−δ catalyst showed better ammonia synthesis performance compared to the commercial iron catalyst (ZA-5), giving prospects for process reorganisation towards energy-efficient ammonia production.

The beneficial effect of Y³⁺ ions incorporated into BaCeO₃ support structure stems from the strengthening of the electron-donating ability, i.e., better charge transfer from the support to the active metal, enhancing N₂ dissociation.