Operando diffuse reflectance infrared detection of cyanide intermediate species during the reaction of formaldehyde with ammonia over V2O5/WO3-TiO2

• Formaldehyde present in exhaust gas can react with NH 3 to produce HCN. This reaction was studied by operando DRIFTS on V 2 O 5 /WO -TiO and TiO at 300 °C. formed adsorbed cyanide species, phase HCN detected. Formic acid reacted but did not form species or production does involve formate Hydrogen (HCN) is a highly poisonous that through the between formaldehyde ammonia (NH ) exhaust. While this detrimental side has been subject of recent catalytic studies under selective reduction conditions, molecular mechanism leading release remains far from elucidated. Here, we report detection intermediate diffuse reflectance infrared spectroscopy, thereby providing unambiguous evidence HCN-forming occurs catalyst surface. likely reacts pre-adsorbed Although were abundantly upon introduction, they responsible for high level emissions observed. alone sufficient catalyze reaction, VO x and/or WO sites increase preventing formation inactive polyamide species. These mechanistic insights should serve as basis understanding chemistry so mitigation measures be put forward.