Non-oxidative coupling of methane over Pd-loaded gallium oxide photocatalysts in a flow reactor

Photocatalytic methane conversion is attractive for utilization of renewable biogas and solar energy to directly produce useful compounds. In the present study, gallium oxide (Ga₂O₃) photocatalyst was examined for non-oxidative coupling of methane (NOCM) around room temperature in a flow reactor. It was found that ethane and hydrogen were continuously yielded at constant rates from methane upon photoirradiation around room temperature, confirming that NOCM can be promoted photocatalytically over Ga₂O₃. In addition, Pd cocatalyst was found to improve the activity of the Ga₂O₃ photocatalyst for NOCM to produce ethane and hydrogen at almost the same constant rate and achieve more than three times higher formation rate of ethane such as 0.22 μmol h⁻¹ in a flow of 10% methane at 30 mL min⁻¹ with 0.8 g of photocatalyst. The methane conversion achieved to 0.006% within a short contact time of 0.8 s, which is higher than the thermodynamic equilibrium conversion.