Synergistic Control and Resource Utilization of Carbonyl Sulfur (COS) and Hydrogen Sulfide (H₂S) over Oxidized K-Mo...

Carbonyl sulfide (COS) and hydrogen sulfide (H₂S) coexist extensively in industrial waste gases, yet conventional technologies typically address them separately, leaving synergistic control and resource utilization as ongoing challenges. This study presents a novel approach for the synergistic catalytic transformation of COS/H₂S into high-value-added methyl mercaptan (CH₃SH). Activity results revealed that the oxidized K-Mo/Al-O catalyst, unexpectedly active, outperforms the common sulfided K-Mo/Al-S catalyst. Characterizations suggested that K-Mo/Al-O undergoes in situ reconstruction into the K-intercalated 1T-MoS₂ phase (K_xMoS₂), subsequently transforming into the K-decorated 2H-MoS₂ phase (K/MoS₂). Structure-activity relationship confirmed K_xMoS₂ as the key metastable active phase for the generation of CH₃SH, where potassium species acted as the primary active site, while Mo oxide/sulfide species played an assistant role. Temperature-programmed surface reaction of reactants (COS/H₂/H₂S-TPSR) and in situ diffuse reflectance infrared spectroscopy (in situ DRIFTS) elucidated that the reaction mechanism strongly depends on both reaction temperature and the active phase types, i.e., K₂MoO₄ precursor follows an Eley-Rideal (E-R)-type direct COS hydrogenation pathway, K_xMoS₂ exhibits a dual-path E-R mechanism (direct COS hydrogenation at low temperature and indirect hydrogenation at medium temperature), and K/MoS₂ primarily follows indirect COS hydrogenation at medium temperatures. This work paves a new avenue for synergistic resource utilization of multicomponent sulfur pollutants.