Unveiling the Effect of Transition Metal Doping on Hg 0 Removal over OMS-2 Sorbents in a Reducing Natural Gas Atmosphere

The interaction strength between Hg0 and surface-active oxygen species of metal oxides is a core factor determining the removal efficiency of Hg0, and this effect is particularly pronounced under a reducing atmosphere of ambient-temperature natural gas. Transition metal doping provides an effective method to regulate the structure and activity of metal oxide oxygen species. However, its structure–activity regulation mechanism in Hg0 oxidation reactions remains unclear, which hinders the directional design of high-efficiency Hg0 removal materials. Herein, we developed a series of transition metal (Cu, Co, and Ce)-doped manganese oxide octahedral molecular sieve (OMS-2) sorbents, among which Cu-doped OMS-2 exhibited optimal ambient-temperature Hg0 oxidation performance, achieving a stable Hg0 removal efficiency of 97%. The type of transition metal and its occupancy site in the OMS-2 lattice directly determine the Hg0 removal performance by regulating the activity of surface lattice oxygen. The incorporation of Cu significantly improved the redox properties and enhanced the activity and mobility of lattice oxygen by adjusting the p-band center, which accelerated the conversion of Hg0 to Hg2+. This strategy provides valuable insights for guiding the design of Hg0 sorbents for application in a reducing natural gas atmosphere at ambient temperature.