Cu-Fe oxide supported on Na2CO3-modified activated carbon boost H2S removal at low temperature

A variety of Cu-Fe oxide supported on Na₂CO₃-modified activated carbon (CuFeNaAC-X) catalysts were prepared via the impregnation and calcination methods and their desulfurization performance was evaluated at low-temperature. By optimizing the loading content of Cu-Fe, the sulfur capacity of the CuFeNaAC-5 reached a maximum of 430.09 mg/g, surpassing most activated carbon (AC) catalysts. EPR testing revealed that the loading of Cu-Fe oxide can activate oxygen to form superoxide radicals (${\text{O}}_{\text{2}}^{\text{-}}$·), thereby promoting the catalytic oxidation of H₂S. XPS testing revealed that upon loading of Cu-Fe oxide, the formation of FeOOH can facilitate the catalytic oxidation of H₂S to sulfur (S) through a chain reaction. Combining EPR and XPS analyses, Na₂CO₃ modification modulates the content of ${\text{O}}_{\text{2}}^{\text{-}}$·, directing the formation of S and then significantly improving the catalyst’s desulfurization efficiency. Furthermore, CO₂-TPD testing revealed that Na₂CO₃ modification promotes the ionization of H₂S to HS^-, thereby enhancing the catalyst’s desulfurization performance. Based on the distribution of sulfur species in used catalysts, and the results of characterizations, a possible desulfurization mechanism of CuFeNaAC-X has been proposed.