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

Abstract

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.