Novel NimCo0.3-mTi0.7Ox (m = 0.05, 0.1, 0.15, 0.25) catalysts with remarkable performance for the selective catalytic reduction of NOx by NH3

Abstract

A serial of novel NimCo0.3-mTi0.7Ox (m = 0.05-0.25) mixed-oxide catalysts was synthesized by sol-gel method, and applied for selective catalytic reduction (SCR) of NOx by NH3. Influences of the Ni/Co ratio on the physico-chemical properties and SCR performance were characterized by various analytical techniques, including BET surface area, XRD, XPS, NH3-TPD, H2-TPR and in situ DRIFTS. The Ni0.1Co0.2Ti0.7Ox catalyst shows optimum NH3-SCR activity and excellent N2 selectivity with a broader activity temperature window (210–450 °C), which is associated with the much higher BET surface area, more surface acid amounts and the suitable redox ability derived from the strong interaction between Co and Ni (Co3+ + Ni2+ ↔ Ni3+ + Co2+). In situ DRIFTS results reveal that the formed monodentate nitrate and NH2 species, as main active intermediates, are favor of the NH3-SCR reaction. The existence of H2O mainly restrains Langmuir-Hinshelwood reaction pathway which may be the main cause for the catalyst deactivation.