Constructing Pd@Layered-CoO_x/MFI Bifunctional Catalyst for Efficient Ethyl Acetate Oxidation: Boosted C═O Activation and *O Species Transformation

Oxygenated volatile organic compounds (OVOCs), emitted in large quantities by the chemical industry, are a major contributor to the formation of ozone and subsequent particulate matter. For the efficient catalytic oxidation of OVOCs, the challenges of molecular activation and intermediate inhibition remain. The construction of bifunctional active sites with specific structures offers a promising way to overcome these problems. Here, the Pd@Layered-CoO_x/MFI bifunctional catalyst with core-shell active sites was rationally fabricated though a two-step ligand pyrolysis method, which exhibits a superb oxidation efficiency toward ethyl acetate (EA). Over this, 13.4% of EA (1000 ppm) can be oxidized at just 140 °C with a reaction rate of 13.85 mmol·g_Pd^-1·s^-1, around 176.7 times higher than that of the conventional Pd-CoO_x/MFI catalyst. The electronic coupling of the Pd-Co pair promotes the electron back-donation from Pd nanoparticles to the layered CoO_x shell and facilitates the formation of Pd²⁺ species, which greatly enhances the adsorption and activation of the electron-rich C═O bond of the EA molecules. In addition, the synergy of these core-shell Pd@Layered-CoO_x sites accelerates the activation and transformation of *O species, which inhibit the formation of acetaldehyde and ethanol byproducts, ensuring the rapid total oxidation of EA molecules via the Mars-van Krevelen mechanism. This work established a solid foundation for exploring robust bifunctional catalysts for deep OVOC purification.