Nonoxidative coupling of methane to ethane over a Pd-Bi deposited titania photocatalyst in a flow reactor

Photocatalytic nonoxidative coupling of methane (photocatalytic NOCM) is a unique strategy for directly converting methane into more valuable C2 hydrocarbons like ethane and ethene at lower temperatures compared to traditional thermo-catalytic methods. In the current study, we developed a Pd-Bi/TiO₂ photocatalyst prepared by a simultaneous photodeposition (PD) method. Under the present conditions, a stable ethane formation rate of 5.8 µmol h^-1 was achieved with 99% ethane selectivity, which is significantly higher than that of previously reported photocatalysts, such as Au/TiO₂ or Pd-Bi/Ga₂O₃ under the same reaction conditions. Part of the deposited Bi under PD conditions partially alloyed with Pd to form Pd-Bi alloy species in the case of the bi-metallic co-catalyst, which are proposed to be responsible for the higher selectivity towards ethane. The synergistic effect of Pd and Bi was studied experimentally.