摘要
Usually, most of the studies on catalytic soot oxidation (CSO) were mainly focused on the characterization of the active sites for metal-based catalysts on soot with loose or tight contact. Here, we reveal new concepts on the effect of the structural properties of soot, carbon black (CB) used as the model candidates, over copper catalysts in the catalytic oxidation of soot. Copper catalysts were prepared using wet impregnation with different copper loadings ranging from 0.1 to 20 wt% on a series of CB serving as model soot. The interaction between copper catalysts and CB were characterized using elemental analysis, Brunauer-Emmett-Teller (BET) surface area analysis, Fourier-transform infrared (FT-IR) spectrometry, high resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD), air-thermal gravimetric analysis (TGA), in-situ CO2-temperature programmed desorption mass spectroscopy (CO2-TPD-MS) and in-situ O2-temperature programmed desorption mass spectroscopy (O2-TPD-MS). XRD patterns indicate the formation of copper oxide species (denoted as CuOx) are formed in the CuOx-CB catalyst system after a 120 ℃ dehydration process. FT-IR spectra depicted clear evidence that CuOx nanoparticles (NPs) were anchored onto CB surfaces and interacted with oxygenated functional groups, e.g., carboxylic (-COOH), indicating a pronounced strong metal-support interaction. The CSO performance evaluated by air-TGA and in-situ O2-TPD measurements reveals that the content of oxygenated groups on CB plays a main role in governing the oxidation mechanism of CB. Additionally, a structural index incorporating oxygen content, aggregate structure, and specific surface area of CB is proposed. Notably, this index exhibits a strong linear relationship with the reduction oxidation temperatures of CB, demonstrating that the combined physicochemical properties of CB provide a more comprehensive descriptor of catalytic oxidation behavior than individual parameters alone. Our findings establish a clear structure-activity relationship between CuOx nanoparticles and carbon substrates, offering new insights into copper-assisted soot oxidation.
•A new concept elucidates how surface oxygenated complexes on carbon govern Cu-catalyzed carbon oxidation.•Carbon oxidation temperature is drastically lowered from 562 to 212 ℃ by copper catalysts.•The redox cycle of copper is dominantly regulated by carbon surface structures rather than gas-phase oxygen.•In-situ CO₂/O₂-TPD-MS reveals distinct interfacial pathways governing low-temperature oxidation.•A clear structure–activity correlation links carbon functionalities with copper redox behavior and catalytic efficiency.