Oxidative Methane Conversion to Ethane on Highly Oxidized Pd/CeO₂ Catalysts Below 400 °C

Methane upgrading into more valuable chemicals has received much attention. Herein, we report oxidative methane conversion to ethane using gaseous O₂ at low temperatures (<400 °C) and atmospheric pressure in a continuous reactor. A highly oxidized Pd deposited on ceria could produce ethane with a productivity as high as 0.84 mmol g_cat⁻¹ h⁻¹. The Pd−O−Pd sites, not Pd−O−Ce, were the active sites for the selective ethane production at low temperatures. Density functional theory calculations confirmed that the Pd−O−Pd site is energetically more advantageous for C−C coupling, whereas Pd−O−Ce promotes CH₄ dehydrogenation. The ceria helped Pd maintain a highly oxidic state despite reductive CH₄ flow. This work can provide new insight for methane upgrading into C₂ species.