ZIF-67-derived hollow dodecahedral Mn/Co3O4 nanocages with enrichment effect and good mass transfer for boosting low temperature catalytic oxidation of lean methane

The greenhouse effect caused by direct emissions of lean methane from coal mining is 25 times greater than that of CO 2 . To reduce the methane content in the atmosphere, it is imperative to develop high-activity, stable, and low cost methane-catalyzed combustion catalysts. In this work, a series of Mn-doped Co 3 O 4 hollow nanocages with dodecahedral shape were prepared using the metal-organic framework (MOF) material ZIF-67 as a template, combined with an in-situ growth method and a high-temperature calcination process. The optimized hollow structure Mn 0.6 /Co 3 O 4 -H (T 90 = 302 °C) exhibited higher catalytic activity than the solid structure Mn 0.6 /Co 3 O 4 -S (T 90 = 387 °C). On the one hand, Mn 0.6 /Co 3 O 4 -H has abundant O ads /O latt (0.61) and high Co 3+ /Co 2+ (1.11) content, which increases the adsorption of reactive molecules. In addition, the adsorption of methane by the Mn 0.6 /Co 3 O 4 -H catalyst reached 0.77 cm 3 /g at 273 K, increasing the methane concentration inside the catalyst. Concurrently, the hollow structure also establishes fast mass and heat transfer channels, leading to a significant improvement in the catalytic performance. The new catalyst developed in this study provides a new perspective and insight for reducing methane emissions during coal mining and reducing its negative impact on the environment.