COS and H2S simultaneous removal from blast furnace gas over a tailored Cu/Zr co-doped K@TiO2 bifunctional catalyst under low temperature

Abstract

The lengthy processes and cumbersome operations for the separate removal of COS and H2S have severely limited the development of blast furnace gas recycling process. CuO exhibits excellent H2S oxidation performance, but weak COS hydrolysis performance; in contrast, ZrO2 shows the opposite trend. However, the functional combination of CuO and ZrO2 has never been used for simultaneous removal of COS and H2S. In this study, a Cu/Zr co-doped K@TiO2 bifunctional catalyst was tailored to simultaneously remove COS and H2S. The combined COS and H2S capacity of this catalyst reaches 340.5 mg/g at a low temperature of 60 °C, which is much higher than those of other reported bifunctional catalysts. The microcrystal structure formed by Cu/Zr co-doping increases the specific surface area of the catalyst and promotes the adsorption of COS/H2S. Specifically, Zr doping increases the content of moderate basic sites and significantly improves the hydrolysis efficiency of COS. Moreover, Cu doping induces lattice distortion of TiO2, while CuO captures 4 s valence electrons of K to form Cu2O. These two processes lead to the release of lattice oxygen from TiO2 and CuO, generating oxygen vacancies and ·O2−, which promotes H2S oxidation. By proposing a simple route for the bifunctionalization of a desulfurization catalyst, this study drives innovation in both the theory and application of simultaneous removal of COS and H2S.