Engineering the electronic structure of Pt-KOx cluster catalyst via alkali metal for efficient oxidative dehydrogenation of propane using CO2

The oxidative dehydrogenation of propane to propylene using CO₂ (CO₂-ODH) offers a promising route for both propylene production and CO₂ utilization. In this study, we investigate the effect of alkali metal doping on Pt-based catalysts in CO₂-ODH reactions. The optimized 0.1KPt/S-1 catalyst achieved a high propane conversion of 48.3 %, propylene selectivity of 85.5 %, and CO₂ conversion of 19.1 % at a low temperature of 500 °C with the Pt loading of 0.2 wt% and K loading of 0.1 wt% respectively. Characterization techniques, including high-resolution transmission electron microscope (HR-TEM), CO-diffuse reflectance infrared Fourier transform spectroscopy (CO-DRIFTS), X-ray absorption fine structure (XAFS), and X-ray Photoelectron Spectroscopy (XPS), revealed that the doping of K with Pt led to a strong interaction between potassium and platinum (Pt-KO_x cluster). This interaction resulted in a reduction of Pt particle size and a local enrichment of electron density around Pt atoms. These structural modifications improved the anchoring of Pt nanoparticles and enhanced Pt atom dispersion, thereby enhancing the activity of the catalyst and minimizing side reactions. Additionally, pyridine infrared (Py-IR) and temperature-programmed desorption (TPD) studies demonstrated that the prepared 0.1KPt/S-1 catalyst exhibited optimal acidity, which promoted C–H activation and facilitated the efficient adsorption and activation of CO₂. These dual effects significantly lowered the activation energy for CO₂-ODH, enabling efficient dehydrogenation to propylene at a lower temperature of 500 °C. This work highlights the critical role of alkali metal doping in modifying the electronic properties of Pt and optimizing catalyst acidity, which collectively contribute to the enhanced performance of the 0.1KPt/S-1 catalyst. These findings offer valuable insights into the mechanistic pathway of CO₂-ODH and provide a foundation for the rational design of high-performance dehydrogenation catalysts.