Rationally Engineering a CuO/Pd@SiO2 Core–Shell Catalyst with Isolated Bifunctional Pd and Cu Active Sites for n-Butylamine Controllable Decomposition

Volatile organic amines are a category of typical volatile organic compounds (VOCs) extensively presented in industrial exhausts causing serious harm to the atmospheric environment and human health. Monometallic Pd and Cu-based catalysts are commonly adopted for catalytic destruction of hazardous organic amines, but their applications are greatly limited by the inevitable production of toxic amide and NO_x byproducts and inferior low-temperature activity. Here, a CuO/Pd@SiO₂ core-shell-structured catalyst with diverse functionalized active sites was creatively developed, which realized the total decomposition of n-butylamine at 260 °C with a CO₂ yield and N₂ selectivity reaching up to 100% and 98.3%, respectively (obviously better than those of Pd@SiO₂ and CuO/SiO₂), owing to the synergy of isolated Pd and Cu sites in independent mineralization of n-butylamine and generation of N₂, respectively. The formation of amide and short-chain aliphatic hydrocarbon intermediates via C-C bond cleavage tended to occur over Pd sites, while the C-N bond was prone to breakage over Cu sites, generating NH₂· species and long free-N chain intermediates at low temperatures, avoiding the production of hazardous amide and NO_x. The SiO₂ channel collapse and H⁺ site production resulted in the formation of N₂O via suppressing NH₂· diffusion. This work provides critical guidance for a rational fabrication of catalysts with high activity and N₂ selectivity for environmentally friendly destruction of nitrogen-containing VOCs.