Synergistic Control and Resource Utilization of Carbonyl Sulfur (COS) and Hydrogen Sulfide (H ₂ S) over Oxidized K-Mo Materials

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 (KxMoS2), subsequently transforming into the K-decorated 2H-MoS2 phase (K/MoS2). Structure–activity relationship confirmed KxMoS2 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, KxMoS2 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.