Ammonia storage/release characteristics of CeSnWBaOx/TiO2 catalyst in solving the problem of ammonia slip

Abstract

The ceria-based catalyst exhibited excellent storage/release characteristics of ammonia, ensuring stable deNOx efficiency under fluctuating engineering conditions, while greatly reducing ammonia slip. In this work, characteristics of ammonia storage/release of CeSnWBaOx/TiO2 catalyst were investigated. Results showed that the catalyst exhibited much higher catalytic activity than the theoretical maximum under low NH3/NO ratios. Especially, the amount of effective ammonia release reached maximum at 250 °C with increase of excess NO. Low temperature was conducive to storage and the stable storage amount was 22.97 μmol·m−2 at 50 °C, effective release of ammonia occurred mainly at the active temperature window. Ammonia storage of the CeSnWBaOx/TiO2 catalyst was affected by the activation of active sites and thermal vibration at the same time. Ammonia storage under low temperature was mainly in physical form and at weak acid sites, while high temperature enhanced activation of ammonia, resulting in an increase of ammonia storage at 350 °C. The catalyst had both weak and strong stored-ammonia, strong stored-ammonia could be effectively released only in the induction of NO. Ammonia storage of catalyst was the key to ensure stable deNOx efficiency under fluctuating engineering condition. The characteristics are of great guiding significance for dealing with ammonia slip.