Speaker
Description
A significant yet often underexplored factor is the role of alkali metals, notably potassium, in catalysis. As a superbase, potassium enhances catalytic performance by promoting substrate deprotonation and molecular activation. This study investigates potassium structural and electronic properties at varying loadings (1, 5, and 10 wt%) using K₂CO₃ and KNO₃ on γ-Al₂O₃ and α-Al₂O₃ supports. Understanding the composition and electronic structure of alkali species is crucial for elucidating their catalytic behaviour, especially since their direct characterisation in catalysis is often overlooked. Potassium, in particular, can significantly alter surface chemistry, stability, and basicity, thereby influencing adsorption, desorption, and reaction pathways. In this study emphasis will be given to potassium XAFS to examine the change in local structure with respect to loading, salt type, heat treatment and moisture effect.
Preliminary XANES spectra indicated that most samples lacked edge splitting, suggesting the absence of pure, dry carbonate, except for K₂CO₃ on α-Al₂O₃ (1 wt%), which retained mild splitting, indicative of dry K₂CO₃. Previous studies confirmed that potassium XANES spectra are sensitive to speciation, correlating with local structural changes.
The findings reveal distinct structural characteristics of K₂CO₃ and KNO₃ on supports, setting the stage for further studies on their impact on heterogeneous catalysis.
