Structured hierarchical Mn–Co mixed oxides supported on silicalite-1 foam catalyst for catalytic combustion

Silicalite-1 (S1) foam was functionalized by supporting manganese–cobalt (Mn–Co) mixed oxides to develop the structured hierarchical catalyst (Mn–Co@S1F) for catalytic combustion for the first time. The self-supporting S1 foam with hierarchical porosity was prepared via hydrothermal synthesis with polyurethane (PU) foam as the template. Subsequently, Mn–Co oxide nano sheets were uniformly grown on the surface of S1 foams under hydrothermal conditions to prepare the structured hierarchical catalyst with specific surface area of 354 m²·g⁻¹, micropore volume of 0.141 cm³·g⁻¹ and total pore volume of 0.217 cm³·g⁻¹, as well as a good capacity to adsorb toluene (1.7 mmol·g⁻¹ at p/p₀ = 0.99). Comparative catalytic combustion of toluene of over developed structured catalyst Mn–Co@S1F was performed against the control catalysts of bulk Mn–Co@S1 (i.e., the crushed Mn–Co@S1F) and unsupported Mn–Co oxides (i.e., Mn–Co). Mn–Co@S1F exhibited comparatively the best catalytic performance, that is, complete and stable toluene conversion at 248 °C over 65 h due to the synergy between Mn–Co oxides and S1 foam, which provided a large number of oxygen vacancies, high redox capacity. In addition, the hierarchical porous structure also improved the accessibility of active sites and facilitated the global mass transfer across the catalyst bed, being beneficial to the catalysis and catalyst longevity.