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

• Published in: Applied catalysis. B, Environmental Environmental, 2024-08, Vol.351, p.123910, Article 123910
• Main Authors: Wu, Linke, Deng, Jiguang, Liu, Yuxi, Jing, Lin, Yu, Xiaohui, Tao, Jinxiong, Gao, Ruyi, Feng, Ying, Dai, Hongxing
• Format: Article
• Language: English
• Subjects: Catalytic oxidation; Dichloromethane; Supported Ru single-atom catalyst; Tin-doped Silicalite-1; Toluene; Volatile organic compound
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2024.123910

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-1-Sn-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 °C for toluene oxidation and T90% = 361 °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 °C were 9.67 μmol/(gcat h) and 0.98 × 10−3 s−1, and specific reaction rate and TOFRu for DCM oxidation at 200 °C were 3.84 μmol/(gcat h) and 0.46 × 10−3 s−1, respectively), excellent catalytic stability (within 100 h of on-stream oxidation at 380 °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 Brønsted acid sites. The high concentration of oxygen vacancies and enriched Brønsted 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. [Display omitted] The doping of Sn to Silicalite-1 leads to the formation of tightly coupled redox and acidic sites, enriches the Lewis acid sites (LAS) and Brønsted acid sites (BAS), increases Ru dispersion, and improves the (dichloromethane (DCM) + toluene) adsorption. The acidic sites in Ru@Silicalite-1-Sn-50 are effective in the dissociation of C−Cl bonds in DCM, and the intermediate products are further oxidized to CO2, H2O, and HCl at the