Catalytic Advancements in NH Selective Catalytic Oxidation: The Impact of Cu-Induced Lattice Distortion in TiO Crystal Structure.

A series of x Cu-TiO obtained from the sol-gel method were tested for NH selective catalytic oxidation (NH-SCO). Its performance was higher than that of supported Cu/TiO-Im and solvent-free Cu/TiO-SF. The catalyst exhibits better water resistance at 300 °C. XRD, Raman, and H-TPR proved that the crystal lattice of TiO was deformed by Cu doping, which increased the specific surface area of the catalyst. The dispersion of the Cu component is further enhanced. The enhancement of redox potential was the key to improving catalytic activity. The NH-TPD results prove that more acidic sites promote more active NH species being adsorbed and dissociated on the catalyst surface. The in-situ DRIFTs results certify that the NH species adsorbed on the Lewis acid sites were easier to consume than those on the Brønsted acid sites. The DFT theoretical calculation demonstrates that the doped Cu promotes the TiO conduction band to move closer to the Fermi level and enhances the redox performance of the catalyst. The results suggest that the Cu-TiO catalyst was a potential catalyst under actual working conditions, which would provide a technological reserve for the development and diffusion of ammonia slip for both mobile and fixed sources.