Our goal is to develop innovative catalytic materials, understand their physicochemical structure and behaviour, and explore applications of such materials in sustainable chemical synthesis, pollution mitigation, and clean energy transformations.

Our research profile builds on the three classical “pillars” of heterogeneous catalysis: (i) synthesis of catalytic materials and supports, (ii) catalyst characterization with a range of physicochemical methods, (iii) catalytic performance testing. Our perspective on each of these is briefly highlighted below.

  • Synthesis: the design and synthesis of innovative porous materials is a focal point of the group. Such nanostructured materials may range from individual crystals or particles (e.g. zeolites), to large scale structured bodies such as monolithic materials. Complex structured materials including hierarchical porous systems are a particular interest.
  • Characterisation: our expertise ranges from classical physical measurement of diffusion properties (e.g. sorption, porosimetry), to spectroscopy and diffraction (e.g. IR, XRD), to spatially-resolved microscopy and related methods (e.g. TEM). We particularly aim to explore the characterization potential of synchrotron radiation and related X-ray analytics, which offer a powerful and flexible toolbox to understand catalyst structure. Chemical contrast modes including XAS, XRF, or XRD can be combined with 3D imaging methods via tomography, to obtain deep structural knowledge of catalysts and functional materials from macro- to nanoscale.
  • Testing: we broadly explore catalytic applications in fields ranging from sustainable chemical transformation (e.g. selective oxidation), to pollution mitigation (e.g. emissions control), to chemical energy storage and conversion (e.g. Power-to-X). In situ / operando methodology is of particular interest in linking the structure of catalysts and functional materials to their catalytic behaviour.

Our Research Projects

Proton exchange membrane electrolyzers are a key technology for green hydrogen production and storage of renewable energy. Understanding degradation of these devices under working conditions is an important step towards application. These degradation processes will be studied with high resolution electron and X-ray imaging methods.

Hierarchical porous alumina monoliths are produced for methanation of CO2. The fabrication of crack-free monoliths up to the cm range as well as the loading with different catalytically active species for the conversion of CO2 are investigated. The materials are further characterized with advanced analytical methods, such as TEM tomography or XRM, in order to investigate and understand diffusion processes.

New silica-support materials inhibiting hierarchical pore structure will be synthesized and characterized and their qualification for application in organo-catalysis will be tested. The hierarchical pore systems with adjustable pore width will be generated by pseudomorphic transformation. These materials will be characterized by standard methods, e.g., nitrogen sorption, X-ray powder diffraction, scanning electron microscopy, as well as by advanced methods like transmission electron microscopy (TEM). Furthermore, the materials are used for the immobilization of organocatalysts, enzymes and others and are investigated with respect to their catalytic activity and the influence of different pore sizes.

enlarge the image: Sol-Gel Synthesis of Large Pore Mesoporous Silica (Autor: M. Gebauer)
Sol-Gel Synthesis of Large Pore Mesoporous Silica (Autor: M. Gebauer)

Nitrous oxide (N2O), an inevitable by-product from adipic and nitric acid production plants, is a recognized global warming agent and contributes to the degradation of the stratospheric ozone layer. The present study aims at providing a broad picture of the effects of different REE (R = Nd, Pr, Ce) on the physicochemical properties of R/M/Al mixed oxides (M = Cu, Co, Ni).  

Industrial sugar production involves separation by chromatography. Currently, the separation principle is based on specific interactions with ions inside a polymeric matrix (ion-exchange resin). The present project tries to find out if these materials can be replaced by zeolites.

enlarge the image: Retention times of various sugars and sugar alcohols in a zeolite-filled HPLC column (Author: M.W. Shakil and C. Buttersack).
Retention times of various sugars and sugar alcohols in a zeolite-filled HPLC column (Author: M.W. Shakil and C. Buttersack).

In the context of biomass-based chemical value chains bifunctional catalysts are necessary for a versatile conversion of complexly functionalized molecules. Metal doped silica materials with acidic polymers embedded into them are investigated as catalysts with tuneable acid and redox properties.

enlarge the image: Scheme for the use of bifunctional catalysts (Author: M. Goepel)
Scheme for the use of bifunctional catalysts (Author: M. Goepel)

Synthesis of metaloxide supports loaded with active metals for the conversion of CO2 to alcohols. Influence of support, active phase and promotor on catalyst performance. Catalysts to be testet in the set-ups of industry partners (enaDyne) on their activity and selectivity in NTP-DBD Plasma. 

Infrared Microscopy is a powerful tool for in-situ investigations of the diffusion and adsorption of a variety of probe molecules into single crystals/particles of porous materials. To better understand the diffusion of technically relevant substances in zeolites, we synthesis and modify large zeolite crystals in terms of their pore system properties and active sites. These allow us to study and understand diffusion and adsorption phenomena, as well as model catalytic reactions in greater detail.

enlarge the image: IR microscopic imaging of probe molecule adsorption inside a single zeolite crystal (Author: P. Seidel)
IR microscopic imaging of probe molecule adsorption inside a single zeolite crystal (Author: P. Seidel)

An attractive and more facile approach for an efficient H2/D2 isotope separation is the utilization of so-called “trapdoor” zeolites. While highly selective separation of D2 from the standard grade H2 was achieved, only moderate efficiency was obtained when the concentration of either species increases beyond low percentile amounts. Combination of this approach with selective electrostatic adsorption in various zeolitic materials is considered to be a promising sustainable and inexpensive route for separation of hydrogen isotopologues.

Carbon capture is a key technology for reaching climate protection goals and lowering the atmospheric concentration of CO2. Effective direct air capture can be achieved using amine-functionalized silica, however such processes are energy intensive and therefore bear financial burden. Coupling carbon capture with the synthesis of value added chemicals can support the viability of the process while simplifying the synthetic approach and making it resistant for dynamic reaction conditions.