Enhancing catalytic CH₄ oxidation over Co₃O₄/SiO₂ core–shell catalyst by substituting Co²⁺ with Mn²⁺

Abstract

Co₃O₄, a transition metal oxide with spinel structure, has attracted wide attention due to its high catalytic activity in the field of catalytic oxidation of low concentration methane. However, due to the harsh conditions of methane catalytic reaction on catalysts, of which the high reaction temperature and complex reaction environment often lead to the deactivation and sintering of Co₃O₄ catalyst, improving the comprehensive performance of Co₃O₄ catalyst has become the current research hotspot and urgent demand. Core-shell flower-spheroidal cobalt-manganese composite catalyst was prepared in this paper by hydrothermal method, which gave full play to the advantages of carrier, special morphology and doping modification, reduced the risk of sintering and deactivation of Co₃O₄, and showed higher catalytic activity. Through SEM, EDS, and BET test and analysis, Mn1/Co/SiO₂ has better microstructure and structure than Co₃O₄/SiO₂. For example, the dispersion of Mn1/Co/SiO₂ and the uniform distribution of elements are higher, and the values of surface area and pore volume are larger (129.956 m²/g → 180.639 m²/g, 0.333363 cm³/g → 0.398030 cm³/g). Combined with XRD and XPS analysis, it is concluded that Mn²⁺ manganese ion replaces Co²⁺ and causes lattice distortion of Co₃O₄, which promotes the production and mobility of reactive oxygen species, further increasing catalytic activity. Compared with Co₃O₄/SiO₂, methane conversion at 350 °C and 450 °C increased by 10% and 6%, respectively.

Graphical Abstract

Keywords:

• Core–shell catalyst
• two-dimensional Co₃O₄ nanosheet
• catalytic oxidation of methane

Additional information

Funding

This work was supported by the National Natural Science Foundation of China under Grant (numbers 21604007, 51474061, and 51704086).