An in situ Fourier transform infrared study on the mechanism of NO reduction by acetylene over mordenite-based catalysts

Selective catalytic reduction of NO with acetylene (C2H2-SCR) over mordenite-based catalysts (HMOR, 0.5% Mo/HMOR and NaMOR) was investigated by in situ Fourier transform infrared spectroscopy. A possible mechanism was proposed to explain catalytic performance of the mordenite-based catalysts in the C2H2-SCR: Nitrosonium ions (NO+) and bidentate nitrate are reactive nitric species towards acetylene at 250 degrees C. Isocyanate species thus formed are then hydrolyzed to acid amide species that are crucial intermediate of the C2H2-SCR. Bridging nitrate species become reactive towards the reductant when reaction temperature increased to 300 degrees C. Molybdenum loading on HMOR zeolite considerably increased the population of bridging nitrate species and therefore enhanced the title reaction above 300 degrees C. (c) 2008 Elsevier Inc, All rights reserved.