Efficient Catalytic Behavior by Cobalt and Manganese Oxides Species Supported on a 3DOM Carbon

Abstract

A series of heterogeneous catalysts was synthesized, characterized, and evaluated for the total oxidation of toluene, a representative volatile organic compound (VOC). Metal oxides (Mn_xO_y, Co₃O₄, and Co₃O₄–Mn_xO_y) were deposited onto three-dimensionally ordered mesoporous (3DOM) carbon. The support exhibited a high surface area (325 m² g⁻¹) and uniform mesoporosity (≈3.7 nm), enabling effective dispersion of the active phases. X-ray diffraction (XRD) and transmission electron microscopy (TEM) confirmed the preservation of the ordered structure after impregnation, whereas x-ray photoelectron spectroscopy (XPS) revealed multiple oxidation states of cobalt (Co²⁺/Co³⁺) and manganese (Mn²⁺/Mn³⁺/Mn⁴⁺), favoring redox cycling and oxygen mobility. Catalytic tests demonstrated that the bimetallic oxide system achieved complete toluene conversion (1000 ppm) with the highest activity (1.35 mol of TOL(Toluene) g⁻¹ s⁻¹), outperforming single-metal catalysts (Co₃O₄/3DOM: 0.84 mol of TOL g⁻¹ s⁻¹; Mn_xO_y/3DOM: 1.22 mol of TOL g⁻¹ s⁻¹).