Cu/TiO₂ adsorbents modified by air plasma for adsorption-oxidation of H₂S

In this study, non-thermal plasma (NTP) was employed to modify the Cu/TiO₂ adsorbent to efficiently purify H₂S in low-temperature and micro-oxygen environments. The effects of Cu loading amounts and atmospheres of NTP treatment on the adsorption-oxidation performance of the adsorbents were investigated. The NTP modification successfully boosted the H₂S removal capacity to varying degrees, and the optimized adsorbent treated by air plasma (Cu/TiO₂-Air) attained the best H₂S breakthrough capacity of 113.29 mg H₂S/g_adsorbent, which was almost 5 times higher than that of the adsorbent without NTP modification. Further studies demonstrated that the superior performance of Cu/TiO₂-Air was attributed to increased mesoporous volume, more exposure of active sites (CuO) and functional groups (amino groups and hydroxyl groups), enhanced Ti-O-Cu interaction, and the favorable ratio of active oxygen species. Additionally, the X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) results indicated the main reason for the deactivation was the consumption of the active components (CuO) and the agglomeration of reaction products (CuS and SO₄^2-) occupying the active sites on the surface and the inner pores of the adsorbents.