Enhanced removal efficiency of multicomponent VOCs over the Sn-doped Silicalite-1-supported Ru single-atom catalysts by constructing tightly coupled redox and acidic sites

The development of cost-effective catalysts with excellent chlorine resistance and harmful by-products inhibition is important for the environmentally friendly purification of multi-component volatile organic compounds (VOCs and chlorine-containing VOCs (CVOCs)). In this work, the Sn-doped Silicalite-1-supported Ru (Ru@Silicalite-1Sn-x, and x is the molar ratio of Si/Sn) samples were prepared using a hydrothermal strategy, and catalytic activities of these materials were investigated for the oxidative removal of mixed VOCs (dichloromethane (DCM) and toluene). The Ru@Silicalite-1-Sn-50 sample with tightly coupled redox and acidic sites exhibited high catalytic activity (T90% = 287 degrees C for toluene oxidation and T90% = 361 degrees C for DCM oxidation at a space velocity of 40,000 mL/(g h); specific reaction rate and turnover frequency (TOFRu) for toluene oxidation at 170 degrees C were 9.67 mu mol/(gcat h) and 0.98 x 10-3 s-1, and specific reaction rate and TOFRu for DCM oxidation at 200 degrees C were 3.84 mu mol/(gcat h) and 0.46 x 10-3 s-1, respectively), excellent catalytic stability (within 100 h of on-stream oxidation at 380 degrees C), and effective inhibition of toxic chlorine-containing by-products formation in the oxidation of (DCM and toluene). The doping of Sn could effectively anchor the Ru atoms to result in single-atom dispersion of Ru and generate oxygen vacancies, and optimized the synergistic interaction between Lewis acid sites and Br & oslash;nsted acid sites. The high concentration of oxygen vacancies and enriched Br & oslash;nsted acid sites promoted the cleavage of C-Cl bonds in DCM and accelerated the desorption of Cl species as inorganic chlorine. In the meanwhile, the strong electron transfer within the Sn-O-Si bond increased the Lewis acidity, which promoted the deep oxidation of dechlorinated intermediates/other intermediates over Ru@Silicalite-1-Sn-50. We believe that the present work provides a feasible and promising strategy for the design of efficient catalysts for the destruction of multicomponent VOCs and CVOCs in an industrial scale.