The preparation and desulfurization of nano-size ZnO by a matrix-assisted method for the removal of low concentration of sulfur compounds

Zinc oxide (ZnO) nano-particles have been synthesized by a matrix-assisted method with various precursors. An activated carbon was used as a matrix and zinc acetate, zinc nitrate, and zinc chloride were selected as precursors. The ZnO nano-particles appeared to be either spherical or elliptical shapes when zinc acetate and zinc nitrate were used as precursors, while those particles became irregular in their shapes when zinc chloride was used as a precursor. The products were characterized by using TGA, XRD, BET, TEM and SEM. A nano-size ZnO was formulated for the effective removal of a very low concentration of sulfur compounds (H2S, COS) contained in a gasified fuel gas and their reactivity was also investigated in this study. Zinc acetate was the best precursor for the formulation of the ZnO nano-particles in the experiment. The size of the formulated ZnO nano-particles was in the range of 10–30 nm and its surface area was about 40.7 m2/g. From TGA (thermal gravity analysis) test, it was found that its sulfur capacity was about 9.27 g S/100 g-sorbent for H2S and 0.56 g S/100 g-sorbent for COS and its initial sulfur absorption rates with H2S and COS absorption were about 257.5 mg S/min · 100 g-sorbent and 15.6 mg S/min · 100 g-sorbent, respectively. Their reactivity increased as their sizes became smaller and their surface areas of the sorbents were larger. Most prepared nano-size ZnO showed an excellent performance for the removal of not only H2S but also COS.