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Efficient catalytic oxidation of VOCs by a Pd-Pt/SiO2 catalyst: The cooperative catalysis of dual metal sites

Jinglei Cui,Yujun Cui,Jingjing Tan,Huirong Zhang,Mengyuan Gu,Long Huang

Volatile organic compounds (VOCs) are one of the main pollutants produced in industrial processes. Catalytic oxidation is an effective method to eliminate VOCs, and the key lies in designing efficient metal catalyst. In this work, Pd-Pt/SiO 2 bimetallic catalysts were designed and prepared by the immobilization method, and their performances for toluene oxidation were evaluated. The addition of Pt into the catalyst elevated markedly the reduction of Pd active sites, leading to abundant electron-deficient Pd 0 and electron-rich Pt 0 in the Pd 2 Pt 1 catalyst, which were confirmed by TEM, CO pulse adsorption and in-situ XPS. As revealed by O 2 -TPD and toluene-TPD characterization, the cooperative effect of electron-deficient Pd 0 and electron-rich Pt 0 in Pd 2 Pt 1 catalyst facilitated the activation of O 2 and toluene, thus enhanced greatly its activity. A conversion of 90% (T 90 ) for toluene was achieved over Pd 2 Pt 1 catalyst at 165 ℃, and the apparent activation energy ( E a ) over Pd 2 Pt 1 catalyst was lower than that over other Pd-Pt bimetallic and monometallic Pd or Pt catalysts. Additionally, the reaction mechanism was studied by In - situ DRIFTS, the results showed that the toluene oxidation passed successively benzyl alcohol, benzaldehyde, benzoic acid and maleic anhydride , then maleic anhydride was further oxidized to CO 2 and water.