High-Temperature Pretreatment Effect on Co/SiO<sub>2</sub> Active Sites and Ethane Dehydrogenation
Kewei Yu, Sanjana Srinivas, Cong Wang, Weiqi Chen, Lu Ma, Steven N. Ehrlich, Nebojša Marinković, Pawan Kumar, Eric A. Stach, Stavros Caratzoulas, Weiqing Zheng, Dionisios G. Vlachos
Abstract
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.