Morphology-dependent Selectivity Switching of CeO2 in Tandem Conversion of Ethane and CO2

Abstract

The tandem conversion of C₂H₆ and CO₂ provides an opportunity to utilize underused shale gas while reducing greenhouse gas emissions efficiently. Although desirable, this transformation poses considerable challenges, particularly in the realm of catalyst design either through CO₂-assisted ethane dehydrogenation (CO₂-EDH) to produce ethene or by dry reforming (DR) to produce syngas. Here, we found that the morphology of CeO₂ could determine which pathway was predominant. Transmission electron microscope (TEM) and X-ray photoelectron spectrometer (XPS) analyses of Pt and Sn showed that the spherical morphology of CeO₂ was more conducive to generating platinum-tin metal clusters than CeO₂ nanorod, illustrating the relatively high C₂H₄ selectivity (93.50%) of the spherical structure. In contrast, the nanorod-shaped CeO₂ demonstrated enhanced activation of reactants and facilitated the reaction towards synthesis gas production, with a remarkable CO₂ conversion rate of 84%, which was much higher than previous works. Electron paramagnetic resonance (EPR) spectroscopy and XPS analysis of oxygen revealed that the nanorod-shaped CeO₂ had more oxygen vacancies, enhancing CO₂ adsorption capacity and promoting the dispersion of active species, which were crucial for efficient tandem catalytic reactions. These findings provide a promising approach to advancing catalyst design for efficient shale gas utilization in a carbon-negative manner.

Graphical Abstract