TY - JOUR A1 - Kaluza, Stefan A1 - Behrens, Malte A1 - Schiefenhövel, Nora A1 - Kniep, Benjamin A1 - Fischer, Richard A1 - Schlögl, Robert A1 - Muhler, Martin T1 - A Novel Synthesis Route for Cu/ZnO/Al2O3 Catalysts used in Methanol Synthesis: Combining Continuous Consecutive Precipitation with Continuous Aging of the Precipitate JF - ChemCatChem Y1 - 2011 U6 - https://doi.org/10.1002/cctc.201000329 SN - 1867-3899 VL - 3 IS - 1 SP - 189 EP - 199 PB - Wiley ER - TY - JOUR A1 - Kaluza, Stefan A1 - Muhler, Martin T1 - On the precipitation mechanism and the role of the post-precipitation steps during the synthesis of binary ZnO–Al2O3 composites with high specific surface area JF - Journal of Materials Chemistry KW - FBMV Y1 - 2009 U6 - https://doi.org/10.1039/b902004g SN - 1364-5501 VL - 19 IS - 23 SP - 3914 EP - 3922 PB - Royal Society of Chemistry (RSC) ER - TY - JOUR A1 - Kaluza, Stefan A1 - Muhler, Martin T1 - On the Role of Aging, Washing, and Drying in the Synthesis of Polycrystalline Zinc Oxide by Precipitation: Combining Fast Continuous Mixing, Spray Drying and Freeze Drying to Unravel the Solid-State Transformations of the Precipitate JF - Catalysis Letters Y1 - 2009 UR - 1572-879X U6 - https://doi.org/10.1007/s10562-008-9818-5 N1 - The authors gratefully acknowledge fruitful discussions with Malte Behrens and Robert Schlögl, and the financial support by the BMBF (Bundesministerium für Bildung und Forschung) within the scope of the project 01RI05028 “Entwicklung von Methanolsynthesekatalysatoren als Basis für nachhaltige Ressourcennutzung” VL - 129 IS - 3-4 SP - 287 EP - 292 PB - Springer ER - TY - JOUR A1 - Failing, Luisa A1 - Kaluza, Stefan A1 - Strucks, Peter T1 - Catalytic CO2 methanation: Providing optimal test conditions for kinetic investigations JF - Chemie Ingenieur Technik N2 - In the context of using renewable energies and recycling climate-changing gases, methanation of CO2 provides one possibility. However, volatile availability of renewable energies for hydrogen production and fluctuating CO2streams from different sources lead to enhanced demand in investigating the influence of dynamic process operation on the catalyst performance, including detailed kinetic characterization. Reliable kinetic measurements require isothermal temperature control and absence of macrokinetic diffusion limitations. Both were investigated in this work while the determination of steady-state kinetic parameters is part of ongoing studies. Furthermore, a detailed analysis with respect to the long-term-stability of the nickel-based catalyst was performed KW - CO2 methanation KW - Kinetics KW - Long-term stability KW - Ni catalyst KW - Power-to-Gas Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:due62-opus-40026 SN - 1522-2640 VL - 95 IS - 5 SP - 749 EP - 753 PB - Wiley ER - TY - JOUR A1 - Winter, Franziska Luise A1 - Diehl, Patrick A1 - Telaar, Pascal A1 - Watermann, Clara Maria A1 - Kaluza, Stefan A1 - Muhler, Martin A1 - Apfel, Ulf-Peter A1 - Zeidler-Fandrich, Barbara T1 - Influence of the catalyst precursor for cobalt on activated carbon applied in ammonia decomposition JF - Catalysis Today N2 - Ammonia is a key compound for storing and transporting green hydrogen. However, the efficient release of stored hydrogen through thermocatalytic ammonia decomposition is achievable only at temperatures around 600 °C, particularly with non-noble metal-based catalysts, which prove to be both ecologically and economically more feasible. In this study, electrically conductive activated carbon was selected as the catalyst support, chosen specifically for its suitability in achieving more energy-efficient direct reactor heating through the ohmic resistance of the catalysts. Cobalt salts were wet impregnated on activated carbon investigating the influence of different precursors (cobalt nitrate and cobalt acetate) and pyrolysis temperatures (400 °C and 600 °C) under N2 flow on the cobalt particle size and the incorporation of cobalt into the carbon matrix. TEM imaging and CO-chemisorption revealed well dispersed cobalt particles with sizes below 10 nm for the catalysts synthesized from the cobalt nitrate precursor. On the other hand, cobalt acetate led to about nine times larger Co agglomerates, which were partially detached from the carbon matrix. Moreover, this substantial difference in the Co particle size results in a significantly higher ammonia conversion for cobalt nitrate-based catalysts, achieving 94 % of ammonia conversion at 600 °C. Furthermore, the long-term stability test of the cobalt nitrate-based catalyst resulted in a slight deactivation of only 2 % ammonia conversion at 500 °C. KW - Katalyse KW - Ammoniak KW - Grüner Wasserstoff KW - Ammonia decomposition KW - Carbon supported cobalt KW - Synthesis design KW - Cobalt acetate KW - Cobalt nitrate KW - Resistance heating Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:due62-opus-46600 SN - 0920-5861 VL - 429 PB - Elsevier ER - TY - CHAP A1 - Wacht, Anika A1 - Kaluza, Stefan A1 - Fleiger, Philipp ED - Leipzig, Konrad von ED - Sacks, Natasha ED - Mc Clelland, Michelle T1 - Carbon Capture and Utilization in Cement Industry—Aspects of the Production of E-Fuels by Upcycling Carbon Dioxide T2 - Smart, Sustainable Manufacturing in an Ever-Changing World: Proceedings of International Conference on Competitive Manufacturing (COMA ’22) KW - Carbon dioxide capture and utilization KW - Synthetischer Kraftstoff KW - Upcycling KW - Kreislaufwirtschaft KW - Zementindustrie KW - Kohlendioxid Y1 - 2023 SN - 9783031156014 U6 - https://doi.org/10.1007/978-3-031-15602-1_44 SN - 2194-0525 SP - 603 EP - 612 PB - Springer Nature CY - Cham ER - TY - JOUR A1 - Greuel, Marc A1 - Watermann, Clara Maria A1 - Lohmann, Heiko A1 - Kaluza, Stefan A1 - Apfel, Ulf-Peter A1 - Zeidler-Fandrich, Barbara T1 - The conversion of ethanol over 3d-metal saponite-like smectites JF - Materials Advances N2 - The replacement of fossil fuel processes with renewable pathways is critical to circumvent climate change and environmental risks. A process of interest is the production of 1,3-butadiene (BD), which is primarily derived as a by-product of naphtha steam cracking. A sustainable alternative path involves converting renewable ethanol to BD via the Lebedev process, which requires a catalyst with balanced redox, acidic, and basic sites. Due to the necessity of a multifunctional catalyst, existing materials for this reaction are either comprised of catalyst mixtures or supported catalysts. In this study, we introduce a bulk material, saponite, containing M–O–Si sites, which combine required catalytic sites for the ethanol to BD (ETB) reaction in one material. The product composition in ethanol conversion were strongly dependent on the type of 3d-metal used, while no conclusive correlation between surface properties, conversion, and product composition was observed. Herein, using V-Sap*, we achieved an ethene productivity of 448 gethene kgcat−1 h−1 (74%) at 573.15 K. High acetaldehyde productivity was maintained with Cu-Sap* (466 gAcA kgcat−1 h−1, 49%) at 573.15 K and Zn-Sap (528 gAcA kgcat−1 h−1, 55%) at 723.15 K. Mg-Sap primarily produced ethene but also yielded 10 gBD kgcat−1 h−1 BD at 723.15 K. Higher BD outputs were observed with Ni-Sap (31 gBD kgcat−1 h−1 at 523.15 K) and Mn-Sap* (51 gBD kgcat−1 h−1 at 723.15 K). This underscores the potential of saponite-based materials for flexible product outputs in ethanol conversion, influenced by the choice of integrated 3d-metal. KW - Butadien KW - Katalyse KW - Material Y1 - 2025 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:due62-opus-52973 SN - 2633-5409 IS - 6 SP - 2885 EP - 2898 PB - Royal Society of Chemistry ER - TY - RPRT A1 - Failing, Luisa A1 - Kaluza, Stefan A1 - Strucks, Peter T1 - Power2Gas - Katalytische Methanisierung von CO₂ als Baustein einer erfolgreichen Energie- und Rohstoffwende N2 - Die katalytische Methanisierung von Kohlendioxid (CO2) mit Hilfe von elektrolytisch erzeugtem Wasserstoff (H2) aus erneuerbaren Energiequellen kann einen wichtigen Beitrag zur Reduktion von CO2-Emissionen leisten. Aufgrund einer immer stärker fluktuierenden Energie- und Rohstoffbereitstellung spielt die Möglichkeit einer flexiblen, dynamischen Betriebsweise eine zunehmend große Rolle für zukünftige Technologien. Dies bedingt auch im Fall der katalytischen Methanisierung umfangreiche Untersuchungen, um zu ermitteln, inwieweit eine dynamische Fahrweise Auswirkungen auf Prozess und Katalysator besitzt. An diesem Punkt setzte das HiFF-Projekt Power2Gas an. So wurden verschiedene nickelbasierte Katalysatorsysteme synthetisiert, wobei sich der via Imprägnierung hergestellte Ni/Al2O3-Katalysator sowohl aufgrund seiner guten Leistung als auch der praktikablen und reproduzierbaren Herstellung als geeignetes Benchmark-System für weitere Untersuchungen - vor allem im kinetischen Bereich - erwies. Während umfassender Parametervariationen wurden kinetische Datensätze im stationären Zustand bestimmt, die zur Modellierung der katalysierten CO2-Methanisierung verwendet werden können. Darüber hinaus wurden in ausgewählten Versuchsreihen die isotherme Temperaturkontrolle und eine ausreichende Langzeitstabilität sichergestellt sowie makrokinetische Diffusionsbeschränkungen ausgeschlossen. Die Ergebnisse wurden in einer peer-review-Publikation veröffentlicht und auf zwei Konferenzen präsentiert. Sie waren zudem die Basis für eine erfolgreiche Masterarbeit und flossen in die Antragstellung im Rahmen des DFG-Programms „Großgeräteaktion für Hochschulen für Angewandte Wissenschaften“ ein. N2 - The catalytic methanation of carbon dioxide (CO2) using electrolytically produced hydrogen (H2) from renewable energy sources represents a potential option for reducing CO2 emissions. Due to an increasingly fluctuating availability of energy and raw materials, the need for flexible, dynamic operation is becoming ever more crucial for future technologies. In the case of catalytic methanation, this also requires further investigations to determine the impact of dynamic operation on the process and catalysts. This is where the HiFF Power2Gas project comes in. Various nickel-based catalyst systems were synthesized. The Ni/Al2O3 catalyst produced via impregnation was identified as a suitable benchmark system for further investigations - particularly in the kinetic range - due to its good performance as well as its simple and reproducible synthesis. By thorough parameter variation, kinetic data sets were determined in steady state, which can be used to model catalyzed CO2 methanation. In addition, isothermal temperature control and long-term stability were ensured in a series of selected experiments, while macro-kinetic diffusion limitations could be ruled out. The results were published in a peer-reviewed publication and presented at two conferences. They were also fundamental for a successful master's thesis and were used in an application for the DFG program "Großgeräteaktion für Hochschulen für Angewandte Wissenschaften". T3 - Berichte zu HSD-intern geförderten Forschungsprojekten - 4 KW - Dekarbonisierung KW - Dynamische Betriebsweise KW - Nickel-Katalysator KW - Deaktivierung KW - Power-to-X KW - CO₂ Methanisierung Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:due62-opus-45143 SN - 2625-3690 CY - Düsseldorf ER - TY - BOOK A1 - Marzi, Thomas A1 - Deerberg, Görge A1 - Dötsch, Christian A1 - Grevé, Anna A1 - Hiebel, Markus A1 - Kaluza, Stefan A1 - Knappertsbusch, Volker A1 - Maga, Daniel A1 - Müller, Torsten A1 - Pflaum, Hartmut A1 - Pohlig, Astrid A1 - Renner, Manfred A1 - Seifert, Ulrich A1 - Stießel, Sebastian A1 - Unger, Christoph A1 - Wack, Thorsten A1 - Weidner, Eckhard T1 - Kohlendioxid, Biomasse und Regenerativer Strom - Ressourcen einer neuen Kohlenstoffwirtschaft? Y1 - 2017 SN - 978-3-87468-358-6 U6 - https://doi.org/10.24406/UMSICHT-N-473349 VL - Umsicht-Diskurs IS - 1 PB - Fraunhofer-Institut für Umwelt-, Sicherheit- und Energietechnik CY - Oberhausen ER -