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A key advantage of freeze-casting preceramic polymers is the ability to work with solutions rather than suspensions, which are inherently limited due to their colloidal nature. Furthermore, solution-based freeze-casting opens access to a wide range of organic solvents, allowing for diverse and controllable pore structures. A limiting factor in polymer-derived ceramics is often the crosslinking step required to stabilize the structures prior to pyrolytic conversion. However, when paired with low-temperature photopolymerization for crosslinking, solution-based freeze-casting offers great flexibility in the design of porous ceramic materials.

In the framework of the “CO₂Refinery” doctoral school at TU Wien, our Ceramics team at the Institute of Chemical Technologies and Analytics has developed porous SiOC ceramics via photopolymerization-assisted freeze-casting of preceramic polymers. These materials have been explored as porous frameworks for a variety of CO2 utilization applications by teaming up with experts from the fields of technical catalysis, organic synthesis, and biotechnology, developing supports for Ni-catalyzed gas phase CO₂ methanation, ionic-liquid-coated scaffolds for liquid phase cycloaddition of supercritical CO₂ with bio-based epoxides to form cyclic carbonates (e.g. for lithium-ion batteries), or substrates for industrially relevant microorganisms, where the aligned macroporosity has been shown to support microbial growth.

We are now extending our material design approach beyond monoliths towards alternative geometries for other reactor designs. While not a simple or singular solution to the CO₂ crisis, this research highlights the promise of early-stage advanced ceramics for future applications in catalysis, energy conversion, or biotechnology.

Freeze-cast SiOCs templated with different structure-directing solvents e. g. cyclohexane (CH) or tert-butyl alcohol (TBA) to support Ni or yeast microorganisms, respectively.

Dipl.-Ing. Katharina Rauchenwald

University assistant, PhD Student

TU Wien

Institute of Chemical Technologies and Analytics

Getreidemarkt 9, 164-CT, 1060 Vienna, Austria 

katharina.rauchenwald@tuwien.ac.at

linkedin.com/in/katharina-rauchenwald-a8448621a