In Situ Local Temperature Mapping in Microscopy Nano‐Reactors with Luminescence Thermometry

In situ and operando experiments play a crucial role in understanding the mechanisms behind catalytic processes. In these experiments it is important to have precise control over pressure and temperature. In this work, we use luminescence thermometry to map the temperature distribution in a 300 mu m microelectromechanical system nano-reactor with a resolution of ca. 10 mu m. These measurements showed a temperature gradient between the center and edge of the heater of ca. 200 degrees C (at T-set=600 degrees C) in vacuum and, in addition, a large offset of the local temperature of ca. 100 degrees C (at T-set=600 degrees C) in a non-vacuum (i. e., air, He and H-2) environment. The observed temperature heterogeneities can explain differences observed in the reduction behavior of Co-based Fischer-Tropsch synthesis catalyst particles at different locations in the nano-reactor as determined by scanning transmission X-ray microscopy.