In Situ Studies on Mechanochemistry/Mechanocatalysis
The basic concept of mechanochemical processes is the introduction of energy, both for the activation of reactants and the catalysts used, by mechanical grinding instead of the supply of thermal or electrical energy. For potential applications this means that both temperature and pressure can be reduced compared to conditions applied in conventional reactors. A further advantage of mechanochemical processes is that solvents are largely or completely dispensed during the reaction. In earlier work of the Department of Heterogeneous Catalysis, catalysis experiments in ball-mills could be carried out without prior catalyst optimization. Although mechanochemistry and mechanocatalysis are becoming increasingly important in practice, the processes taking place during the grinding process are largely unknown.
in situ X-ray diffraction experiments allow the observation of structural phase changes or microstructural properties during a reaction (operando investigations). This requires an adaptation of the grinding jars to the experimental requirements of both the reaction and the respective beamline of the synchrotron. To obtain detailed information about mechanisms during mechanochemical reactions, in situ synchrotron diffraction experiments are combined with vibrational spectroscopy.
Amrute, A. P., Lodziana, Z., Schreyer, H., Weidenthaler, C., & Schüth, F. (2019). High-surface-area corundum by mechanochemically induced phase transformation of boehmite. Science, 366(6464), 485-489. doi: 10.1126/science.aaw9377.