Investigation of the promotional effect of V2O5 on the SCR reaction and its mechanism on hybrid catalyst with V2O5 and TiO2-SO42− catalysts

Hybrid V2O5 and TiO2-SO42− catalysts used in selective catalytic reduction (SCR) reaction of NO with NH3 have been studied by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), SCR, temperature-programmed reaction (TPR), and NH3-temperature-programmed desorption (TPD). Single phase or bi-phasic catalyst disposed in non-adjacent layers in a reactor show an improved activity and an expansion of the reaction temperature window, as compared with the sum of the individual activity of the pure phase. In the presence of V2O5 on hybrid catalysts, DRIFTS shows that the NH2 and nitrate species appear at a lower temperature than in pure TiO2-SO42− catalyst. The improved reactivity of NH3 in NH3-TPD by NO and TPR is also closely related to the enhanced formation of NH2 species. As a result, the high reactivity in hybrid catalysts can be explained by the promotional effect of V2O5 leading to the high rate of formation of NH2 and nitrate species at lower temperature.