Flower-like Co3O4 Catalysts for Efficient Catalytic Oxidation of Multi-Pollutants from Diesel Exhaust

Abstract

Nowadays, the oxidation activity at the low-temperature regime for Co3O4 catalysts needs to be improved to meet the stringent regulation of multi-pollutant diesel exhaust. Herein, nanoflower-like Co3O4 diesel oxide catalysts (DOCs) were fabricated with the addition of a low-content Pt to trigger better catalytic activities for oxidizing multi-pollutants (CO, C3H6, and NO) emissions by taking advantage of the strong-metal supporting interaction. Compared to the conventional DOCs based on Pt/Al2O3, the as-synthesized Pt/Co3O4 catalysts not only exhibited better multi-pollutants oxidation activities at the low temperature but also obtained better resistance toward NO inhibition. Moreover, Pt/Co3O4 catalysts showed exceptional hydrothermal durability throughout long-term tests in the presence of water vapor. According to the XPS and H2-TPR results, Pt promoted low-temperature catalytic activity by increasing the active surface oxygen species and reducibility due to the robust synergistic interaction between metallic Pt and supporting Co3O4. Meanwhile, TGA curves confirmed the Pt atoms that facilitated the desorption of surface-active oxygen and hydroxyl radicals in a low-temperature regime. Furthermore, instead of probing the intermediates during CO and C3H6 oxidation for Pt/Co3O4 catalysts, which included carbonates, formate, and acetate species, in situ DRIFTs experiments also revealed C3H6 oxidation mainly took place over metallic Pt sites.

Catalytic dehydration of glycerol over Cu–Fe–Al-based oxides: understanding changes in active sites throughout the reaction

“… 52 This type of hysteresis and isotherm profile are characteristic of mesopores solid, slit-shaped pores and particle aggregates. 53 The changes between Fe10Al90 and Fe10Al90Cu solids when compared to Fe20Al80 and Fe20Al80Cu are related to the type of pore and the mechanisms involved in N 2 adsorption/desorption process. Furthermore, the regions with low relative pressure values confirms the presence of micropores.…”

Metal Encapsulation-Driven Strong Metal–Support Interaction on Pt/Co3O4 during CO Oxidation

“…We suppose that the contradictory results of Pt/m-Co 3 O 4 with Au/TiO 2 are associated with the high reducibility of Co 3 O 4 promoting the encapsulation even under moderate temperatures, as well as the different surface energy of metals. The more drastic encapsulation of 2 nm Pt/m-Co 3 O 4 is attributed to the plentiful Pt–Co 3 O 4 interface, which has higher reducibility than the Co 3 O 4 surface. , …”

“…The more drastic encapsulation of 2 nm Pt/m-Co 3 O 4 is attributed to the plentiful Pt−Co 3 O 4 interface, which has higher reducibility than the Co 3 O 4 surface. 52,53 The ex situ HR-TEM (Figure 2D) and in situ DRIFT measurements (Figures 2E and S8) were utilized for investigating the encapsulation of Pt NPs by Co 3 O 4 overlayer during CO oxidation. The structural and morphological changes, such as the collapse of mesoporous structure or sintering of Pt NPs, were not observed after the CO oxidation (Figure S9).…”