Creating hierarchically macro-/mesoporous Sn/CeO2 for the selective catalytic reduction of NO with NH3

Abstract

A hierarchically macro-/mesoporous Sn/CeO₂ (H-Sn/CeO₂) catalyst with uniform element composition and dispersion was successfully synthesized by using KIT-6 as a hard template for the selective catalytic reduction (SCR) of NO with NH₃. This catalyst was mainly characterized by such techniques as transmission electron microscopy, scanning electron microscopy, X-ray diffraction, laser Raman spectroscopy, N₂ adsorption–desorption analysis, X-ray photoelectron spectroscopy, H₂ temperature-programmed reduction and NH₃ temperature-programmed desorption. The obtained catalyst possesses hierarchical nanostructures with large specific surface area and good dispersion of elements. It was found that the hierarchically nanostructured Sn/CeO₂ catalyst exhibited high NH₃-SCR activity and a broad operating temperature window. It has been demonstrated that the Sn atoms incorporate into the crystal lattice of ceria, and more Ce³⁺ and O_α species exist on the surface of H-Sn/CeO₂. It is interesting that the doping of Sn element could improve the reducibility of the H-Sn/CeO₂ catalyst due to the synergetic interaction between Ce and Sn species. In addition, the H-Sn/CeO₂ catalyst possesses more acidic sites and stronger acidic strength. Therefore, the obtained catalyst exhibits excellent stability and water resistance as well as enhanced SO₂ tolerance.