Research Fellows Directory
Dr Nico Fischer
Heterogeneous catalysts are at the heart of 90% of all relevant industrial processes to date. Understanding the working principles and processes of structural changes of these catalysts and their effects on activity and selectivity of a reaction is of highest interest not only to the academic community but also to the industrial application. To shed light on these issues it is of utmost importance to study the catalyst system of choice under realistic reaction conditions, i.e. with in situ experimentation probing surface as well as bulk characteristics. We have recently been able to show for the first time experimentally a reaction product (water) induced phase change from the active metallic to the inactive oxide phase in a transition metal catalyst. Theoretical predictions describing a crystallite size dependency of this process in the nanometer size regime could be confirmed. Only below a critical crystallite size of few nanometers, the water induced re-oxidation was feasible under reaction conditions. We strongly believe that this effect is not a singularity but can be expanded to other highly relevant phase changes such as the caburization, reduction, and crystallite growth through sintering. We propose to combine the available in situ bulk material characterization techniques at the University of Cape Town with the surface science techniques at the Cardiff Catalysis Institute to identify these proposed size, shape and phase dependencies of phase changes in metal and metal oxide catalysed synthesis gas conversion reactions.