Mechanistic insight into reaction behaviors of acetonitrile catalytic combustion over Cu-based catalysts with different supports

A series of Cu-based catalysts with different types of supports (TiO 2 , Al 2 O 3 , S-1, HZSM-5 SiO 2 /Al 2 O 3 =   27 and 85) were investigated for selective catalytic combustion of acetonitrile (CH 3 CN). Among all catalysts, the Cu/TiO 2 and Cu/Al 2 O 3 catalysts had superior activity accompanied with the generation of massive NO x , while Cu/ZSM-5 catalysts exhibited excellent N 2 selectivity. The characterization results indicated that the surface acidity of catalysts played a decisive role in reaction behavior. For the Cu/TiO 2 and Cu/Al 2 O 3 catalysts mainly with Lewis acid sites, CH 3 CN underwent an initial hydrolysis step with surface hydroxy group to form acetamide anion (CH 3 CONH ad ), then occurred further hydrolysis reaction to form NH 3 at low temperatures, or turned to proceed oxidation reaction with numerous NO x generation at high temperatures. Whereas, the enriched Brønsted acid sites on the Cu/ZSM-5 catalysts brought abundant isolated Cu 2+ ions, which guaranteed the processing of iSCR reaction, thereby promoting the occurrence of hydrolysis and oxidation reaction pathways in parallel and benefiting the improvement of N 2 selectivity. These results elucidated the influence of supports with different acidic types in reaction pathway and provided precious reference for the development of high-performance NVOCs catalysts.