Catalytic oxidation of carbon black under the conditions of a weak contact in the presence of M/Ce0.72Zr0.18Pr0.1O2, where m is platinum, palladium, and ruthenium

Abstract

Nanodisperse M/Ce0.72Zr0.18Pr0.1O2 catalysts, where M is Pt, Pd, and Ru in amounts of 0.5, 1.0, and 2.0 wt %, for the afterburning of carbon black in the exhaust fumes of diesel engines under the conditions of a weak contact are synthesized. The structural, textural, and catalytic properties of the samples are studied by means of energy dispersive X-ray spectroscopy (EDX), synchrotron X-ray diffraction, X-ray absorption near-edge spectroscopy (XANES), extended X-ray absorption fine structure (EXAFS), transmission electronic microscopy (TEM), low-temperature nitrogen adsorption, and thermogravimetric analysis-differential scanning calorimetry (TG-DSC). It is shown that metal-support interaction, growing in the order Pt → Pd → Ru, occurs as platinum metals are impregnated into the surface of a Ce0.72Zr0.18Pr0.1O2 support. Ruthenium-containing catalysts are the ones most active for the afterburning of carbon black, due not only by the nature of the impregnated component, but also to the relatively ill-defined metal-support interaction, as compared to platinum and palladium samples. An ∼190°C drop in the temperature of oxidation onset and an ∼120°C drop in the temperature of complete oxidation, relative to these same parameters for a support free of platinum group elements, is characteristic of these. The high activity of 0.5%Ru/Ce0.72Zr0.18Pr0.1O2 enables us to purify diesel exhausts of carbon black effectively while using relatively small amounts of the noble metal, making it possible to lower the price of catalyst converters of diesel exhausts.