Ammonia Abatement via Selective Oxidation over Electron-Deficient Copper Catalysts.

Selective catalytic ammonia-to-dinitrogen oxidation (NH-SCO) is highly promising for the abatement of NH emissions from flue gas purification devices. However, there is still a lack of high-performance and cost-effective NH-SCO catalysts for real applications. Here, highly dispersed, electron-deficient Cu-based catalysts were fabricated using nitrogen-doped carbon nanotubes (NCNT) as support. In NH-SCO catalysis, the Cu/NCNT outperformed Cu supported on N-free CNTs (Cu/OCNT) and on other types of supports ( activated carbon, AlO, and zeolite) in terms of activity, selectivity to the desired product N, and HO resistance. Besides, Cu/NCNT demonstrated a better structural stability against oxidation and a higher NH storage capacity (in the presence of HO vapor) than Cu/OCNT. X-ray photoelectron spectroscopy revealed that the surface N species facilitated electron transfer from Cu to the NCNT support, resulting in electron-deficient Cu catalysts with superior redox properties, which are essential for NH-SCO catalysis. By temperature-programmed surface reaction studies and systematic kinetic measurements, we unveiled that the NH-SCO reaction over Cu/NCNT proceeded via the internal selective catalytic reaction (-SCR) route; , NH was oxidized first to NO, which then reacted with NH and O to form N and HO. This study paves a new route for the design of highly active, HO-tolerant, and low-cost Cu catalysts for the abatement of slip NH from stationary emissions via selective oxidation to N.