Mn–Fe bi-metal oxides in situ created on metal wire mesh as monolith catalysts for selective catalytic reduction of NO with NH3

Abstract

In this work, we use an Fe wire mesh to provide homogeneous nucleation sites to support a continuous in situ growth of Mn–Fe bi-metal oxides as monolith catalysts for selective catalytic reduction of NO with NH₃. The strategy of a “twin iron source” makes the Mn–Fe seeds easily grow on the Fe wire mesh through the surface Fe metal sites rather than free growth. The Fe wire mesh exhibited excellent affinity properties with Mn–Fe hydroxides precursor. Through the calcination treatment, a spinel structure of Mn–Fe bi-metal oxides coated monolithic catalyst was prepared and used for denitrification. By adjusting the ratio of the Mn–Fe precursors, we obtained Mn–Fe bi-metal oxides with various morphologies coated on the surface of Fe wire mesh. Impressively, the cube-like Mn–Fe bi-metal oxides structure on the Fe wire mesh as monolith catalysts exhibited high De-NO_x performance, catalytic activity, stability, H₂O tolerance, K⁺ poisoning resistance and regeneration performance. The results showed that the spinel structure of Mn–Fe bi-metal oxides in the coating layer was the critical factor for enhanced adsorption behaviours and reducibilities, which promoted selective catalytic reduction of NO with NH₃. The good adhesion between the Mn–Fe spinel and Fe wire mesh contributed to the super stability and the strong adsorption properties of NH₃, which made it dominant in the NH₃ adsorption process competing with water. The obtained monolith catalysts showed good resistances to K⁺ poisoning and good regeneration performance, which can be attributed to the structural stability of Mn–Fe spinel and strong synergistic effect between the support and active species. This new kind of monolithic catalyst prepared by an in situ technique can be used as a potential substitute for vanadium based ceramic catalysts.