Atomically dispersed Pd-Mn dual-metal doped CeO₂ nanorods for efficient methane oxychlorination.

Abstract

The oxyhalogenation of methane to mono-halogenated methane CH₃X (X = Cl, Br, or I) is one of the most feasible routes for the utilization of methane, but the current catalysts still suffer from limited product yield due to the overoxidation of CH₄ into CO and CO₂ at high conversion levels. Herein, we demonstrate a CeO₂ nanorod catalyst with the surface fabricated by atomically dispersed Pd and Mn for efficient methane oxychlorination (MOC). The optimum Pd-Mn/CeO₂ catalyst offers an MOC performance with a CH₃Cl selectivity of 72% at CH₄ conversion of 33% at 450 °C, stably operating for over 500 h without deactivation. The state-of-the-art performance is attributed to the formation of two synergistic sites with complementary properties, i.e., Pd-O-Ce and Mn-O-Ce centers, which modulate the activation of HCl and O₂, respectively. Both in situ spectroscopy and theoretical calculations identify the metal-O-Cl species as a key intermediate in the reaction network. The MOC reaction catalyzed by Pd-Mn/CeO₂ achieves about 10% lower life-cycle carbon emissions than the traditional route and retains this advantage across platform-chemical-to-PVC conversion pathways.