Multi-component zirconia–titania mixed oxides: Catalytic materials with unprecedented performance in the selective catalytic reduction of NOx with NH3 after harsh hydrothermal ageing

Abstract

Standing harsh hydrothermal treatment (∼10% H2O, ∼1050K) is a prerequisite for deNOx catalysts of tomorrow in diesel exhaust gas treatment. New catalytic materials composed of Mn-, Fe- and Ce-ZrTiSiW mixed oxide were evaluated in the selective catalytic reduction NO by NH3 at high gas hourly space velocity (330,000mLg−1h−1) and after high temperature hydrothermal treatment, 16h at 1023K in H2O/air (10/90). They were compared with a Fe-ZSM5 SCR catalyst treated in the same manner. CeZrTiSiW exhibits the best performance and keeps high NO conversion (>80%) from 630 to 800K. It is stable and fully selective to N2 up to 823K. It is more active and selective than Fe-ZSM5. The presence of NO2 in the feed (NO2/NO=0.85) boosts the NO conversion by shifting the light-off temperature (50% NO conversion) from 560K to 460K.