Revealing the Correlation Between Surface Acid Sites and Activity of VPO/TiO2 Catalyst

In this study, the acid sites on the surface of the catalyst were quantitatively analyzed by pyridine adsorption infrared spectroscopy. When the molar ratio of V/P is 5, the molar ratio of HCl/V is 3, and the calcination temperature is 450 °C, the selective catalytic reduction effect of NO over VPO/TiO2 catalyst is the best (up to 99% at 200 °C), and the acidity of the catalyst is the highest, which is 5600 μmol·g−1. The results showed that the SCR activity of VPO/TiO2 catalyst increased with the increase of acidity at low temperature. Furthermore, the correlation between the denitration activity and the surface acid level was established by means of data fitting. The results showed that the low temperature denitrification activities of all VPO/TiO2 catalysts were positively correlated with the content of weak Lewis acid center (correlation coefficient > 0.9). In conclusion, this study provides a new method for analyzing the structure–activity relationship of the catalyst and provides some theoretical basis for the design of NH3-SCR catalyst.