Promotional effects of ascorbic acid on the low-temperature catalytic activity of selective catalytic oxidation of ammonia over Pt/SA: effect of Pt 0 content

Low-temperature selective catalytic oxidation (SCO) is one of the important strategies used to remove the NH 3 slip upstream of NH 3 selective catalytic reduction (NH 3 -SCR). We have systematically studied the influence of the dispersity of active species, particle size and Pt 0 content on the catalytic activity of ammonia oxidation with a Pt-based catalyst. Ascorbic acid was added to the modified Pt/SiO 2 –Al 2 O 3 catalyst by the co-impregnation method for selective catalytic oxidation of ammonia (NH 3 -SCO), to explore the influence of different properties of the active components on the catalytic activity. It was found that addition of ascorbic acid changed the Pt 0 content in the catalyst. Further studies found that increase in the Pt 0 content could effectively promote activation of oxygen and facilitate more rapid conversion of O 2 molecules to oxygen atoms. Thus, the dehydrogenation reaction of ammonia and oxygen atoms was promoted and proceeded at a lower temperature, improving the low-temperature activity of the NH 3 -SCO reaction. At the same time, it was shown that the Pt 0 content in the system was the key factor affecting the NH 3 -SCO reaction, and this was confirmed by X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, H 2 temperature-programmed reduction and in situ diffuse-reflectance infrared Fourier transform spectroscopy.