Acidic TiNb2O7 nanospheres supported with CeO2 to enhance NH3-SCR denitrification activity and resistance to H2O and SO2: Synergistic effect of CeO2 and TiNb2O7

TiNb2O7 material can be selected as the good support for NH3-SCR catalysts because of its shear structure and surface acidity. Increasing the acidity of catalyst is the key to achieving excellent NH3-SCR performance. In this work, m%CeO2/TiNb2O7 (m = 1, 2, 5, 8 and 10) catalysts were prepared by adjusting the Ce amount supported on TiNb2O7 with good acidity. Among them, 8%CeO2/TiNb2O7 exhibited good activity, N2 selectivity, and excellent SO2/H2O resistance. A series of analytical techniques were employed to examine the relationship among catalyst structure, surface properties and performance. The results show that the short-range ordered Cen+-O2--Nbn+ and Cen+-O2--Tin+ species from interactions between CeO2 and acidic support TiNb2O7 result in improved redox ability and acidity (especially Bronsted acids). The influence of SO2/H2O on SCR reaction and the reaction mechanism were researched using in-situ DRIFTS. The results indicate that SO2/H2O can promote NH3 adsorption and slightly inhibit NOx adsorption. The SCR reaction over 8%CeO2/TiNb2O7 mainly follows the E-R mechanism within the activation window, thus, the influence of SO2 and H2O on the reaction pathway is low, which probably contributes to the better tolerance against SO2 and H2O of the catalyst.

Automated summary

TiNb2O7 material with its shear structure and surface acidity is a good support for NH3-SCR catalysts. The key to achieving excellent NH3-SCR performance lies in increasing the acidity of the catalyst. In this study, catalysts with different amounts of CeO2 supported on TiNb2O7 were prepared, and 8%CeO2/TiNb2O7 exhibited good activity, selectivity, and resistance to SO2/H2O. Analytical techniques were employed to investigate the relationship between catalyst structure, surface properties, and performance. The results show that CeO2-TiNb2O7 interactions improve the redox ability and acidity of the catalyst by forming short-range ordered Cen+-O2--Nbn+ and Cen+-O2--Tin+ species.