Selective catalytic reduction of NO with NH3 over the SAPO-34 supported transition metal nanocatalysts

Abstract

A series of M/SAPO-34 (M=Cu, Fe, Co, and Mn) nanocatalysts was prepared via homogeneous deposition precipitation (HDP) using urea as the precursor for the precipitating agent, and further characterized by N2 adsorption, TEM, H2-TPR and NH3-TPD. The catalytic activity of these nanocatalysts was evaluated for the selective catalytic reduction (SCR) of NO with NH3 as reductant in the presence of excess oxygen. The highest catalytic activity was obtained for the Cu/SAPO-34 nanocatalyst. The TEM and BET results indicated that M/SAPO-34 nanocatalysts have a well-dispersed state of metal species on support and the loaded metal species presenting in nanoscale caused an increase in external surface area of SAPO-34. According to H2-TPR and NH3-TPD profiles, the catalysts’ behavior for NO conversion depends mainly on the redox properties of the metal species and also acidity of catalysts. The high SCR activity on the Cu/SAPO-34 nanocatalyst is attributed to better low-temperature redox properties of copper species and its high acidity.