Ambient Temperature Formaldehyde Oxidation on the Pt/Na-ZSM-5 Catalyst: Tuning Adsorption Capacity and the Pt Chemical State

Catalytic oxidation is believed to be the most efficient method for indoor formaldehyde purification. Herein, we reported that the Pt/Na-ZSM-5 catalyst with low Pt loading (0.16 wt %) prepared by depositing Pt on Na+ ion-exchanged ZSM-5 could completely oxidize 300 ppm formaldehyde in 2.5 vol % H2O at 32 °C and maintain its activity during the 62 h-long stability test. Multiple characterizations revealed that the presence of Na species significantly enhanced formaldehyde adsorption ability and made Pt species tend to exist in the form of metal Pt through electron transfer from Na to Pt, which promoted the activation of oxygen and opened a new efficient formaldehyde oxidation pathway, namely, direct decomposition of formate. The synergistic effects resulted in the TOF of Pt(0.16)/Na-ZSM-5 being about nine times higher than that of Pt(0.50)/ZSM-5. Our study showed that utilizing an alkali metal to tune the surface acidity/basicity of the support and the state of the supported noble metal was a promising way to improve the intrinsic catalytic performance and reduce noble metal usage.