SO32−/SO42− functionalization-tailorable catalytic surface features of Sb-promoted Cu3V2O8 on TiO2 for selective catalytic reduction of NOX with NH3

SO2 is notorious to poison the catalytic surface during the selective catalytic reduction of NOX with NH3 (NH3-SCR). Nonetheless, the use of poisonous SO2 and O2 as surface modifiers to generate the surface metal-SOY2− species (Y = 3 or 4) can be one of the viable ways for promoting catalytic NH3-SCR consequence. To develop a novel catalyst that is highly active in and selective to NH3-SCR, we previously explored four catalytic copper vanadates and determined the optimum active phase (i.e., Cu3V2O8, denoted as Cu3) that revealed the greatest NH3-SCR performance, when combining with a proper Sb quantity of 1.4 wt. %. While using anatase (TiO2) as a support, this study investigated the effect of SOY2− functionalization temperature on the surface property of the optimum catalyst, Sb-promoted Cu3V2O8 on TiO2 (Cu3-Sb1.4/TiO2). Cu3-Sb1.4/TiO2 was subjected to SOY2− functionalization at 300, 400, and 500 °C, leading to the formation of S300, S400, and S500. Although the catalyst surface was not fully functionalized with the SOY2− species in S300-S500, various metal sulfate or sulfite species appeared on the surfaces and showed distinct surface features. The SOY2− functionalization of Cu3-Sb1.4/TiO2 could not increase the quantity of Lewis acid sites. However, 400 °C was deemed as an adequate SOY2− functionalization temperature for increasing the quantity of Brӧnsted acid sites and the redox behavior of the intact Cu3-Sb1.4/TiO2. This could result from the increase in the surface abundance of Cu(SO4) or from a proper combination of the metal-bound SOY2− species with mono-dentate and bi-dentate binding configurations. Apart from exhibiting moderate tolerance to hydrothermal aging, S400 was also validated to improve its resistance to alkali-metal, H2O, SO2, (NH4)2SO4, or (NH4)HSO4 in comparison to its SOY2−-unfunctionalized counterpart, S300, and S500.