Construction of a relay reaction system with Co@S-1 and In-Ce/H-Beta for selective catalytic reduction of nitrogen oxides with methane

Abstract

Selective catalytic reduction of nitrogen oxides with methane (CH₄-SCR) is an effective way to simultaneously eliminate NO_x and CH₄ emissions. Development of an efficient CH₄-SCR reaction system with high NO_x reduction activity and selectivity is highly desirable for its commercial application. Herein, a two-part relay reaction system, including sequential Co@S-1 and In-Ce/H-Beta catalysts, is designed for boosting CH₄-SCR. In this system, Co@S-1 with high redox ability boosts NO oxidation to NO₂ and generates key intermediate CH₃NO₂ that can partially be in situ oxidized and the excess can migrate to In-Ce/H-Beta. Meanwhile, the inner synergistic effect between InO⁺ and CeO₂ species on In-Ce/H-Beta not only exhibits fair CH₄-SCR performance, but also facilitates the formation of NO₃⁻ species to react with the migrated CH₃NO₂ from Co@S-1. Benefiting from the combination between outer active site synergy and inner active site synergy, the simultaneous efficient conversion of NO_x (T₅₀ = 380 °C) and CH₄ (T₅₀ = 425 °C) is achieved.