Preparation and Reactivity test of Nano Size ZnO for Removal of H2S and COS in a Gasified Fuel Gas

摘要

A nano-size zinc oxide was formulated for the effective removal of a very low concentration of sulfur compounds (HiS, COS) contained in a gasified fuel gas and their reactivity was also investigated in this study. They were prepared by a matrix-assisted method with various precursors. An active carbon was used for a matrix and zinc nitrate, zinc chloride, and zinc sulfate were selected as precursors. Zinc nitrate was the best precursor for the formulation of the nano-size zinc oxide in the experiments. The size of the formulated nano-size zinc oxides was in the range of 20-30 nm and its surface area was about 56.2 m2/g. From TGA(thermal gravity analysis) test, it was found that its sulfur capacity was about 5.83 gS/100 g-sorbent and sulfur absorption rate was about 0.363 gS/mirrlOO g-sorbent. Their reactivity increased with the smaller size and the larger surface area of the sorbents. Most prepared nano-size zinc oxides showed an excellent performance for the removal of not only H2S but also COS. Their absorption rate was faster than commercial zinc oxides. In order to investigate the sulfur absorption characteristics of zinc oxide, a experiments for the nano-size zinc oxides formulated from zinc nitrate precursors were carried out in a packed-bed reactor system over the temperature of 500℃. It was concluded that the zinc oxide prepared by zinc nitrate as a precursor showed the highest sulfur removing capacity.