May 2025
Ph.D. DEFENSE COMMITTEE
Advisor: Professor Jorge Gascon (Chemical Engineering, Project Affiliated with Chemistry)
Chair: Professor Ingo Pinnau (Chemical Engineering)
External Committee Member: Professor Alexander Knebel (Friedrich Schiller University Jena, Otto Schott Institute of Materials Research, Germany)
Internal Committee Member: Professor Luigi Cavallo (Chemistry)
Additional Committee Member: Anastasiya Bavykina
Abstract
Separation technologies and catalysis play a crucial role in tackling global energy challenges and advancing sustainability. This dissertation explores innovative strategies to enhance transport of molecules through complex material architectures, of primary importance for applications for gas separation and catalysis.
These newly developed materials are demonstrated for application in mixed matrix membrane (MMM) technology and catalysis. In parallel, electron microscopy characterization is widely used to gain a better understanding into structure property relationships.
Chapter 1 introduces metal-organic frameworks (MOFs), porous liquids (PLs), MMMs, 3D ordered macroporous architectures, and electron microscopy as the primary investigative method. It outlines the research motivation, objectives, and scope.
Chapter 2 focuses on advanced electron microscopy techniques, including Focused Ion Beam Scanning Electron Microscopy (FIB-SEM) and Transmission Electron Microscopy (TEM), for characterizing MMMs at the nanoscale. These techniques enable correlation between structure and performance.
Chapter 3 explores the synthesis of porous liquids using eight different MOFs and their incorporation into MMMs. Surface modification with N-heterocyclic carbenes enhances MOF dispersion stability, improving membrane processability, mechanical strength, and separation efficiency.
Chapter 4 investigates ordered macroporous ZIF-67 as an MMM filler. The macroporous network allows polymer penetration, ensuring superior homogeneity and interfacial interaction with 3-10 µm-sized MOF particles. The resulting membranes exhibit exceptional performance in propylene/propane separation, benefiting from an extended sieving path. FIB-SEM tomography characterizes MOF particles and final membranes in 3D.
Chapter 5 develops a synthesis method for Fe-based MOFs with ordered macroporous architecture. These materials serve as precursors for macroporous Fe3O4@C, which demonstrates efficacy in heterogeneous catalysis.
Chapter 6 concludes with a summary and future perspectives.
Key contributions include:
Expanding of electron microscopy application for MMM characterization;
Novel surface modification strategies for liquid-phase processable MOFs;
Creation of high-performance MMMs with enhanced mechanical and separation properties;
A method to integrate 3-10 µm-sized fillers into MMMs without compromising mechanical integrity.
Development of synthesis of Fe-based MOF in ordered macroporous architecture.
This research offers methodological advancements and material innovations that enhance membrane science. Its findings contribute to academic knowledge while providing practical solutions for more efficient and sustainable separation technologies.
