The investigation of mechanism of SCR reaction on a TiO2-SO42- catalyst by DRIFTS

The intermediates and the mechanism of the SCR reaction of NO with NH3 on TiO2 sulfate have been studied by Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS), FT-IR and NH3-TPD. In the presence of ammonia on the surface, NO adsorbed as NO- species are enhanced and then oxidized to NO2 and NO3- by oxygen either from structure or NO. The formation of NO3- species perturbs the adsorption of protonated ammonia and induces its removal as N-2 at 300 degrees C. The result obtained from FT-LR shows that the NH3 species adsorbed on Lewis acid site remain as main species at high temperature. Accordingly, a Langmuir-Hinshelwood mechanism on Lewis acid site is suggested. (C) 2000 Elsevier Science B.V. All rights reserved.