The preparation of a high surface area metal oxide prepared by a matrix-assisted method for hot gas desulphurization

Abstract

Metal oxide sorbents with high surface area for ultra hot gas cleanup were prepared by a matrix-assisted method. A granular type of activated carbon was used as a matrix in order to increase the surface area of the metal oxide. Zinc was loaded on the surface of activated carbon by an impregnation method. Metal oxide maintained in the form of a matrix structure was observed by scanning electron microscope (SEM). A Wurtzite structure of ZnO was also confirmed by XRD measurement of the prepared granular particles. Particle sizes of metal oxide were distributed in the range of 5–50 nm in transmission electron microscope (TEM) images. The surface area of the zinc oxide calcined at 500 °C was around 56 m 2/g. The values of the particle size and the surface area were directly related to the temperatures of calcination. The curves of sulphidation rates for the zinc oxides with high surface areas were measured by a Cahn balance at several different calcination temperatures. It was found that a catalyst with a large surface area showed a high activity in the desulphurization. Not only sulphur content in a simulated coal gas was completely removed by the ZnO with high surface area but also COS formed by a secondary reaction was not detected in the sulphidation tests performed in a fixed-bed reactor system. It was believed that the high surface area ZnO prepared in this study is a suitable sorbent for the ultra hot gas cleaning from the experimental results.