Template‐free Scalable Synthesis of Flower‐like Co_3‐xMn_xO₄ Spinel Catalysts for Toluene Oxidation

Abstract

The rational design of low-cost transition metal catalysts that exhibit high activity and selectivity may be the most significantly investigated in heterogeneous catalysis. In this study, Co 3-x Mn x O 4 (x = 0.75, 1.0, and 1.5) mixed metal oxides were successfully synthesized by a controlled template-free autoclave strategy and studied for toluene oxidation. It is found that the Co-rich sample showed markedly enhanced activity and the 3D dandelion-like Co 2.25 Mn 0.75 O 4 catalyst exhibited in the highest toluene oxidation rate (8.9 mmol/(g cat s)) and a 100 % toluene conversion at 239 8C. In situ DRIFTS study indicates that toluene was sequentially oxidized to benzyl radical, benzaldehyde, benzene, oxalic acid, and finally to CO 2 and H 2 O. The interaction between Co and Mn, in conjunction with the high concentration of surface oxygen species and rich surface oxygen vacancies, reasonably explains the elevated catalytic activity and thermal stability for toluene oxidation over 3D flower-like Co 3-x Mn x O 4 spinel catalysts.

Self-Templating Synthesis of 3D Hierarchical NiCo2O4@NiO Nanocage from Hydrotalcites for Toluene Oxidation

“…Oxides designed for hierarchical hollow nanostructures with a large surface-to-volume ratio and interconnected pathways for both electrons and ions are of great significance for catalytic oxidation [14][15][16]. Wang reported template-free scalable synthesis of flower-like Co 3−x Mn x O 4 spinel catalysts for toluene oxidation due to rich surface oxygen species over a 3D flower-like structure [17]. Templating-engaged methods employing chemical etching are considered a facile approach, forming hollow structures through the controlled assembly of the desired shells on templates [18].…”

Integral structured Co–Mn composite oxides grown on interconnected Ni foam for catalytic toluene oxidation

“…[22][23][24][25][26][27] Additionally, extensive efforts have revealed that the synergistic effect of Co species and other transition metal oxides has dramatically enhanced the redox properties and catalytic activities due to the formation of a solid solution, compared with single oxides. 11,[28][29][30][31] For example, Jiang et al 30 reported the preparation of Mn-Co-O x nanocubes with different Mn/Co molar ratios derived from metal-organic frameworks. It is shown that hierarchical Mn-Co-O x mixed metal oxides exhibited the better redox properties, more exposed active sites and superior oxidation performances of total toluene oxidation.…”

Hydrothermal Synthesis of a Novel Double‐Sided Nanobrush Co3O4 Catalyst and Its Catalytic Performance for Benzene Oxidation

“…A previous study discovered that Co 3 O 4 catalysts with different morphologies (rods, sheets, plates, cubes, belts and spheres, etc .) exhibit different catalytic properties ,. For instance, Hu et al.…”

“…[16][17][18][19][20][21][22][23] Tricobalt tetraoxide (Co 3 O 4 ), one of the most promising materials, has been used in catalytic oxidation, lithium-ion batteries as energy storage materials, sensor devices and other important fields. [24][25][26][27][28] A number of studies have focused on Co 3 O 4 for the catalytic oxidation of VOCs due to its high catalytic activity, low cost and environmental benignity. A number of references show that the morphology of a catalyst can greatly affect its catalytic performance.…”

“…exhibit different catalytic properties. [25,[28][29][30][31][32][33] For instance, Hu et al reported that three Co 3 O 4 catalysts with different morphologies (nanosheets, nanobelts, nanocubes) showed obvious morphology-dependent methane removal abilities. The activity followed the order of nanocubes < nanobelts < nanosheets.…”