The focus of our research team is on catalyst development and technologies for chemical energy storage as essential core element of a successful energy transition. In addition, the integration of carbon dioxide in the production of industrial basic chemicals, a crucial component of a circular economy, is investigated. Thus, chemical hydrogen storage for safe and energy-dense transport, the promising valorisation of carbon dioxide and the climate-neutral production of synthetic fuels are part of our field of research. The storage of generated renewable energies with a typically highly fluctuating character in chemical energy storage systems not only allows for medium- and long-term conversion, but also enables the global transport of such harvested energy units from regions with more favourable framework conditions than, for example, Germany. These new technological challenges, just like the sustainable economic production of industrial basic chemicals, can only succeed with new catalyst materials and catalytic processes. Hence, we combine fundamental and applied research to achieve significant improvements in energy storage technologies. This research follows an interdisciplinary approach between catalysis, engineering and material sciences. Furthermore, aspects related to advanced separation processes, fuel cells and apparatuses are studied by the team.
The main field of research is the release of hydrogen from liquid organic hydrogen carriers (LOHCs). The LOHC technology avoids transport and storage of highly flammable molecular hydrogen. Aromatic molecules, such as benzyltoluene (BT) can be reversibly hydrogenated to perhydro-BT (H12-BT) and dehydrogenated to H0-BT in order to store and transport hydrogen in form of diesel-like liquids. These LOHCs are typically non-flammable, have a low toxicity, a wide liquid range as well as a high storage density for hydrogen. Further, this chemical storage of hydrogen may even employ existing infrastructure for liquid fuels enabling safe and facile global supply chains. However, the technical release of hydrogen requires rather high reaction temperatures due to the strongly endothermic nature of the dehydrogenation reaction. Hence, the efficient hydrogen release at low reaction temperatures is of particular interest. This topic comprises the development and up-scaling of novel catalysts and their application in various reactor concepts. Further, novel process routes towards higher overall efficiencies are investigated in our team.
The first step in the development of new catalyst materials is to understand the origin of observed activity, selectivity and stability against multiple mechanisms of catalyst deactivation. However, comparative characterisation of the catalyst before and after its application in a chemical reactor is only meaningful for samples that have the same composition and structure after removal of the reaction atmosphere and are stable under ambient conditions. However, many of the catalytically and economically interesting transition metals are pyrophoric, i.e. they oxidise with strong heat release as soon as they are exposed to ambient air. This high instability prevents the characterisation of such catalysts in the activated state or after their application, which means that only limited conclusions can be drawn about their actual state under reaction conditions. Furthermore, dynamic structural changes occurring during activation or catalysis cannot be traced. However, an understanding of these relationships is essential to understand the link between structure-reactivity and structure-stability. Therefore, investigation of catalysts under reaction conditions, so-called in situ or operando characterisation, is gaining increasing interest. With the insights and knowledge gained, new design catalysts of the future can be developed, which allow the increase of activity, selectivity and stability.