High-Temperature Pretreatment Effect on Co/SiO2 Active Sites and Ethane Dehydrogenation

We report the synthesis, optimization, and characterization of Co/SiO2 for ethane nonoxidative dehydrogenation. Co/SiO2 is synthesized via strong electrostatic adsorption using the widely available Co(NO3)2 as the precursor. We demonstrate that high-temperature pretreatment (900 °C) in an inert atmosphere can significantly enhance the initial activity of the Co/SiO2 catalyst. X-ray absorption near-edge spectroscopy (XANES), temperature-programmed reduction (TPR), and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) suggest that highly dispersed Co(II) clusters are more active than Co0 or CoOx nanoparticles. Fourier transform infrared (FTIR) and isopropanol (IPA) temperature-programmed desorption and density functional theory (DFT) calculations suggest that high-temperature treatment significantly increases the density of active Lewis acid sites, possibly via surface dehydroxylation of the catalyst.