Enhancing Deep Mineralization and Chlorine Resistance in Methyl Ethyl Ketone Destruction by Taming Synergy of WOx and Pd Sites

Abstract

Accelerating deep oxidation while restraining the hazardous intermediate formation remains a great challenge in oxygenated volatile organic compounds (OVOCs) catalytic purification. Herein, we found that the modulation of electronic metal–support interactions (EMSIs) in Pd/WO_x/Al₂O₃ catalysts significantly facilitates the deep oxidation of methyl ethyl ketone (MEK) and markedly enhances the CO₂ selectivity. Over the Pd/WO_x/Al₂O₃ catalyst, 90% of MEK can be fully oxidized at just 140 °C with a low apparent activation energy (E_a) of 19.65 kJ·mol^–1, much superior to that of the commercial Pd/Al₂O₃ catalyst (E_a of 80.81 kJ·mol^–1). The EMSIs promote charge redistribution through the unified Pd-WO_x sites, which modulates the d-band structure of highly dispersed Pd sites and strengthens the adsorption and activation of reactants. The positively charged Pd²⁺ species are dominant in activating MEK molecules at low temperatures, and the stretched W–O bonds enhance the activation of lattice oxygen species to participate in subsequent oxidation, ensuring the rapid total oxidation of MEK molecules via the Mars-van Krevelen mechanism. Furthermore, the bifunctional Pd-WO_x sites can also facilitate the dissociation of H₂O and CH₂Cl₂ molecules, enhancing the water-vapor and chlorine resistance of the Pd/WO_x/Al₂O₃ catalyst, which expands the potential toward practical applications. This work sheds significant guidance for researchers to engineer efficacious catalysts toward industrial OVOCs deep elimination.