Selective Synthesis of Ethane from Methane by a Photocatalytic Chemical Cycle Process

Integration of a photon-driven chemical cycle process with a continuous flow reactor, together with the Co_0.2Pd_1.8-TiO_0.2 catalyst, achieves a C₂H₆ yield of 3.7 µmol h⁻¹ with the 100% selectivity during 43 cycles of CH₄ conversion under oxygen-lean conditions. This chemical cycle consists of a controlled NOCM and the subsequent regeneration of the catalyst, thereby enhancing both techno-economic viability and safety of this process.

Abstract

Synthesis of value-added chemicals from methane remains a great challenge due to its high energy requirement, low conversion efficiency, and unavoidable over-oxidation of desired products. Here, the integration of a photon-driven chemical cycle process with a continuous flow reactor over the Co_0.2Pd_1.8-TiO₂ catalyst has led to the continuous synthesis of C₂H₆ from CH₄ with ≈100% selectivity under ambient conditions, simultaneously avoiding mixing flammable gas methane with O₂ for the chemicals production. Such high selectivity and activity are due to the active lattice oxygen of PdO_L and the oxygen-lean condition characterized in the chemical cycle, together with Co single atoms for the regeneration of the photocatalyst surface during the chemical cycle process. The consumed oxygen in PdO_L can be compensated by air during the subsequent catalyst regeneration process, leading to the stable activity during a 43 cycles test. Furthermore, this work to some extent demonstrates that the chemical cycle process not only improves the technoeconomic viability but also enhances safety of the process.