Rationally Engineering a CuO/Pd@SiO₂ Core-Shell Catalyst with Isolated Bifunctional Pd and Cu Active Sites for...

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 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. 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.