Open-cell Foams as Catalyst Support: A Description of Morphology, Fluid Dynamics and Catalytic Performance Offenzellige Schäume als Katalysatorträger: Beschreibung von Morphologie, Fluiddynamik und katalytischer Performance Der Technischen Fakultät der Friedrich-Alexander-Universität Erlangen-Nürnberg zur Erlangung des Doktorgrades Dr.-Ing. vorgelegt von Amer Inayat aus Lahore Als Dissertation genehmigt von der Technische Fakultät der Friedrich-Alexander-Universität Erlangen-Nürnberg Tag der mündlichen Prüfung: 31.10.2013 Vorsitzende des Promotionsorgans: Prof. Dr.-Ing. Marion Merklein Gutachter/in: Prof. Dr. rer. nat. Wilhelm Schwieger Prof. Dr.-Ing. Carolin Körner Parts of this work were already published or submitted to Chemical Engineering Science, Advanced Materials, Advanced Engineering Materials and Chemie Ingenieur Technik: A. Inayat, H. Freund, T. Zeiser, W. Schwieger, Determining the specific surface area of ceramic foams: The tetrakaidecahedra model revisited, Chemical Engineering Science, 66 (2011) 1179–1188 A. Inayat, J. Schwerdtfeger, H. Freund, C. Körner, R.F. Singer, W. Schwieger, Periodic open-cell foams: Pressure drop measurements and modeling of an ideal tetrakaidecahedra packing, Chemical Engineering Science, 66 (2011) 2758–2763 A. Inayat, H. Freund, A. Schwab, T. Zeiser, W. Schwieger, Predicting the Specific Surface Area and Pressure Drop of Reticulated Ceramic Foams Used as Catalyst Support, Advanced Engineering Materials, 13 (2011) 990–995. S. Lopez-Orozco, A. Inayat, A. Schwab, T. Selvam, W. Schwieger, Zeolitic Materials with Hierarchical Porous Structures, Advanced Materials, 23 (2011) 2602–2615 W. Schwieger, S. Lopez, A. Inayat, H. Freund, T. Selvam, Zeolite-Containing Materials with Hierarchical Porous Structures, Chemie Ingenieur Technik, 84 (2012) 1427-1427 Additional journal publications: G.E. Schröder-Turk, W. Mickel, S.C. Kapfer, M.A. Klatt, F.M. Schaller, M.J.F. Hoffmann, N. Kleppmann, P. Armstrong, A. Inayat, D. Hug, M. Reichelsdorfer, W. Peukert, W. Schwieger, K. Mecke, Minkowski Tensor Shape Analysis of Cellular, Granular and Porous Structures, Advanced Materials, 23 (2011) 2535-2553 I. Paramasivam, A. Avhale, A. Inayat, A. Bosmann, P. Schmuki, W. Schwieger: MFI-type (ZSM-5) zeolite-filled TiO2 nanotubes for enhanced photocatalytic activity. Nanotechnology 20 (2009) 225607 (5pp) A. Avhale, G.T.P. Mabande, A. Inayat, W. Schwieger, T. Stief, R. Dittmeyer, Defect-free zeolite membranes of the type BEA for membrane reactor applications, Chemie Ingenieur Technik, 81 (2009) 1090-1090 Für meine Eltern und Alexandra Acknowledgements The present work was carried out between February 2007 and February 2012 in the Institute of Chemical Reaction Engineering at the Friedrich-Alexander-University Erlangen- Nuremberg, Germany. At this point, I would like to express my gratitude and thanks to all who contributed to this work. • My first and foremost gratitude goes to my supervisor Prof. Dr. Wilhelm Schwieger (head of the research group “Heterogeneous Catalysis and Porous Materials”) for accepting me as a researcher and giving me the chance of conducting my PhD work in his group. I am grateful for his continuous guidance and keen interest in my work. Under his supervision not only I learned to carry out research independently, but also to perform collaborative research in an effective manner. I am truly thankful for all his help, support and encouragement in both professional and personal matters. • My special thanks go to Prof. Dr. Hannsjörg Freund (head of the research group “Catalytic Reactors and Process Technology”) for his help, useful advice and insightful discussions during this work. • I would like to thank Prof. Dr. Peter Wasserscheid (head of the institute), Prof. Dr. Bastian Etzold (head of the research group “Chemical Vapor Processes and Catalytic Materials”), Prof. Dr. Nadejda Popovska-Leipertz and Prof. Dr. Martin Hartmann (director of ECRC, Erlangen) for their acceptance, encouragement and facilitation. • Collaborative work with the other departments and institutes as well technical assistance from their personnel was an important element towards the successful completion of the present work. In this regard, I would like to thank Prof. Dr. Carolin Körner and Prof. Dr. Robert F. Singer (WTM Erlangen) for accepting the idea of a collaborative work on the EBM structures and I would like to express my gratitude to Dr. Jan Schwerdtfeger (ZMP, Fürth) and Peter Heinl (WTM, Erlangen) for manufacturing the SEBM structures (periodic cellular structures) for this work. I further take the opportunity to thank Dr. Herald Wiehler and Johannes Hartmann (WTM, Erlangen) for performing the computed tomography measurements. I am grateful to Tobias Heidig and Dr. Enrico Bianchi (Prof. Dr. Hannsjörg Freund’s group) for their useful inputs also during the time when they were at MPI, Magdeburg, Germany. I would also like to thank Prof. Dr. Peter Greil and Dr. Tobias Fey (Institute of Glass and Ceramics, Erlangen), Prof. Dr. Delgado and Tobias Horneber (LSTM, Erlangen), Prof. Dr. Cornelia Rauh (TU Berlin) and Dr. Thomas Zeiser (RRZE, Erlangen) for their cooperation. Acknowledgements • A valuable contribution to this work was made by the students who wrote their bachelor/master thesis for the topic as well as who worked as student research assistant. In this respect, I would like to express my thanks and appreciation to Stephanie Reuss, Markus Probst and Matthias Kick for their worthwhile roles. • My sincere gratitude is rendered to all members of Schwieger research group for providing a friendly and enjoyable working atmosphere. I am especially thankful to Dr. Abhijeet Avhale, Dr. Saiprasath Gopalakrishna and Dr. Jürgen Bauer for their help and support during the very initial phase of my PhD work. I owe thanks to Alexandra Inayat, Sofia Lopez-Orozco, Stephanie Reuss, Marcelle Fankam, Elena Pleissner, Yingxue Zhang, Michael Klumpp, Jimmi Ofili, Andreas Schwab, Dr. Thangaraj Selvam, Hasan Baser, Dr. Ayyappan Ramakrishnan, Hendryk Partsch and Regine Mueller for being friendly and supportive colleagues. I am also thankful to the colleagues in other research groups at CRT as well as at ECRC. • I would like to acknowledge the vital contribution of friendly, capable and competent CRT staff. Sincere thanks go to Mr. Michael Schmacks, Mr. Achim Mannke and Mr. Julian Karl (mechanical workshop), Mr. Gerhard Dommer and Mr. Karl-Heinz Ksoll (electrical workshop and IT), Mr. Walter Fischer and Mr. Hendryk Partsch (IT) and Mr. Helmut Gerhard. I am truly thankful to Mrs. Michelle Menuet, Mrs. Petra Singer, Mrs. Petra Weber and Mrs. Monika Bittan for the enduring support in administrative issues. • To all my family members and friends goes my deepest gratitude without whose unwavering support, continuous encouragement and unconditional love I would never have made it this far. Here, I am especially grateful to my wife Alexandra and daughter Karla for their patience, perseverance and understanding during this busy time of my life. • Finally, I gratefully acknowledge the funding of the German Research Council (DFG), which, within the framework of its `Excellence Initiative´ supports the Cluster of Excellence `Engineering of Advanced Materials´ at the University of Erlangen-Nuremberg. Erlangen, October 2013 Amer Inayat ii Kurzbeschreibung In der chemischen Prozessindustrie kann die Verwendung von strukturierten Reaktoren (z.B. Wabenkörper und Schäume) verschiedene Nachteile, wie z.B. hohen Druckverlust und Hotspots herkömmlicher gepackter Festbettreaktoren vermeiden. Deswegen wurden strukturierte Reaktoren (oder strukturierte Katalysatoren) in den vergangenen Jahrzehnten intensiv als Alternative zur Festbettreaktor-Technologie untersucht. Die bekanntesten und erfolgreichsten Beispiele für den technischen Einsatz strukturierter Reaktoren sind wabenförmige monolithische Katalysatoren, die aufgrund ihrer hervorragenden Eigenschaften (wie z.B. besonders geringes Verhältnis zwischen Druckverlust und geometrischer spezifischer Oberfläche) in den meisten Anwendungen im Umweltbereich die Standard- Katalysatorform geworden sind. Allerdings fehlen den Wabenkörpern aufgrund ihrer geraden Kanäle ohne Vernetzung einige andere reaktionstechnisch wichtige Eigenschaften, wie z.B. Strömungstortuosität und radiale Vermischung. Offenzellige Schäume hingegen vereinen aufgrund ihrer hohen Porosität und dreidimensionalen zellulären Struktur die Vorteile von Festbetten (z.B. radiale Vermischung und Strömungstortuosität) und Wabenkörpern (hohe geometrische spezifische Oberfläche und geringer Druckverlust). Allerdings sind Schäume trotz ihrer hervorragenden Eigenschaften noch nicht in großen kommerziellen Operationen als Ersatz für konventionelle Festbetten angewendet worden. Dies kann mit ihren hohen Herstellungskosten, dem Mangel an ausreichenden Kenntnissen über Transportprozesse in derartigen Strukturen, sowie mit mangelnden Erfahrungen im Umgang mit Schäumen begründet werden. Das Hauptziel dieser Arbeit war es, die Probleme im Zusammenhang mit der Bestimmung der Transporteigenschaften von offenzelligen Schäumen anzugehen. In dieser Hinsicht wurde zunächst eine umfassende Charakterisierung der offenzelligen Schäume hinsichtlich ihrer morphologischen Kenngrößen durchgeführt. Zudem wurde für offenzellige Schäume eine Gleichung zur theoretischen Vorhersage ihrer geometrischen spezifischen Oberfläche, die relevant für Wärme und Stofftransport ist entwickelt. Zu diesem Zweck wurde die Tetrakaidecahedron-Geometrie verwendet, bei der es sich um eine effizient