SO₂-Tolerant Catalytic Removal of Soot Particles over 3D Ordered Macroporous Al₂O₃-Supported Binary Pt–Co Oxide Catalysts

Abstract

The catalytic purification of soot particles is dependent on the SO₂ tolerance and activity of the catalysts in practical application. Herein, we have elaborately fabricated the nanocatalysts of three-dimensionally ordered macroporous (3DOM) Al₂O₃-supported binary Pt-cobalt oxide nanoparticles (NPs) using the method of gas bubbling-assisted membrane precipitation (GBMP), abbreviated as Pt-CoO<i>_x</i>/3DOM-Al₂O₃. Three-dimensionally ordered macroporous Al₂O₃ support can not only improve the contact performance between the soot and active sites but also possess surface acidity to improve the SO₂ tolerance. Supported binary Pt-CoO<i>_x</i> NPs over 3DOM-Al₂O₃ have high-efficient properties for activating NO and O₂. The Pt-CoO<i>_x</i>/3DOM-Al₂O₃ catalyst exhibits super catalytic performance and SO₂ tolerance during the removal of soot particles, whose values of turnover frequency (TOF) and <i>T</i>₅₀ are 0.29 h^-1 and 368 °C, respectively. The catalytic and SO₂-tolerant mechanisms of the Pt-CoO<i>_x</i>/3DOM-Al₂O₃ catalyst for soot purification are systematically studied by in situ diffuse reflectance infrared Fourier transform (DRIFT) spectra. The synergistic effect of binary Pt-CoO<i>_x</i> NPs plays a vital role in the oxidation of NO to NO₂ as a key step during catalytic soot removal, and the surface acidity of 3DOM-Al₂O₃ can not only inhibit the adsorption of SO₂ but also enhance the decomposition of surface hydrosulfate species. This work provides a novel strategy to the development of high-efficient catalysts for SO₂-tolerant catalytic removal of soot particles in both fundamental research and practical applications.