Remarkable enhancement of dichloromethane oxidation over potassium-promoted Pt/Al2O3 catalysts

A series of K-promoted Pt/Al2O3 catalysts were prepared by an incipient wetness impregnation method and tested for oxidation of dichloromethane (DCM). It was found that the activity was greatly enhanced by the modification of K, which depended on the K content in the catalyst. The T50 temperature on a 0.42K–2Pt/Al2O3 catalyst was 270 °C, which was much lower than that on a K-free 2Pt/Al2O3 catalyst (400 °C). The remarkable improvement of activity was attributed to the enhanced catalyst reducibility, by the generation of Pt–O–Kx (x ≈ 2) surface species through an intimate interaction between K and Pt. The presence of such Pt–O–Kx species in the catalyst could significantly accelerate the decomposition of formate intermediates formed on Al2O3 surface and thus the overall reaction, as evidenced by the in situ Fourier transform infrared spectroscopic results.