Construction of a Fe-Ce-OV coordination environment on in situ exfoliated layered double hydroxide nanosheets and its application in the resource utilization of low-concentration SO2 flue gas

Abstract

The reduction of SO₂ to elemental sulfur using CO is an effective approach for comprehensively utilizing flue gas generated by the non-ferrous metal smelting industry, while simultaneously enabling the resource recovery of sulfur. Existing research has demonstrated that non-thermal plasma (NTP)-enhanced catalysis is an effective method for utilizing SO₂, and enhancing the adsorption–desorption process is key to promoting the Eley–Rideal (E-R) and Langmuir–Hinshelwood (L-H) mechanisms. Based on this concept, a MgAl layered double hydroxide (LDH) loaded with bimetallic Fe and Ce active sites was exfoliated using Ar plasma to generate ultrathin FeCe/MgAl-LDH nanosheets. In addition, oxygen vacancies (O_V) were introduced into the ultrathin MgAl-LDH nanosheets, ultimately constructing a P-FeCe/MgAl catalyst with a Fe-Ce-O_V coordination environment. The ultrathin FeCe/MgAl-LDH nanosheets facilitated the exposure of abundant basic/active sites, thereby enhancing the adsorption and activation of SO₂ and its reaction intermediates. Moreover, the Fe-Ce-O_V coordination environment shifted the reaction pathway toward the reduction of carbonyl sulfide (COS), leading to a SO₂ reduction efficiency of 79% under ambient pressure at low temperatures. Overall, the results of this study demonstrate that enhancing the adsorption–desorption process is an effective strategy for reinforcing the E-R and L-H reaction mechanisms, while in situ exfoliation and the construction of coordination environments further promote SO₂ adsorption/conversion and enable directional control over the reaction pathway.