Potassium Poisoning Effects on Sol‐gel Mn/TiO2 Catalyst for Selective Catalytic Reduction (SCR) of NOx with NH3 at Low Temperature

Abstract Mn/TiO 2 catalysts exhibited more excellent activity and higher selectivity in low‐temperature SCR of NOx with NH 3 . Alkali metal, particularly potassium presented in the ash, could severely deactivate SCR catalyst and then reduce its lifetime. In this study, sol‐gel Mn/TiO 2 catalyst was employed to evaluate its SCR activity with and without the presence of KNO 3 at 100–300 °C. The influence of various parameters such as KNO 3 loading amount, calcination time, temperature and catalyst deactivation was investigated. The characterization results indicated that the doping of potassium on Mn/TiO 2 surface obviously resulted in a great decrease of reducibility, surface acidity and NH 3 adsorption capacity. XPS spectra revealed the decrease of Mn 4+ atomic concentration and chemisorbed oxygen species caused by potassium doping. In addition, obvious variation of potassium states (K 1.04 Ti 8 O 16 ) was detected for K−Mn/TiO 2 catalyst after calcining treatment, which may lead to a poorer performance of SCR catalyst.