Sulfidation of Fe₂O₃-SiO₂ Particles in Coal Gas from Air Blown Gasifiers

Abstract

Fe₂O₃-SiO₂ particles, which removes 112S and COS in hot coal gas, are prepared. The characteristics of sulfidation are studied using simulated coal gas from an air blown gasifier.
In the temperature range of 623 K to 973 K, the conversion rate of Fe₂O₃-SiO₂ particle to iron sulfide was slowest at 823 K where Fe₂SiO₄ is formed at reduction before sulfidation. At lower than 823 K, the stable formation is Fe₃O₄. The conversion rate is of first order in 112S concentration. At more than 823 K, however sulfidation does not proceed in lower 112S concentration than 1,000 ppm-2,500 ppm levels. At temperature 823 K, this concentration is lower than 2,460 ppm, which is higher than the equilibrium concentrations (175 ppm).
In the temperature ranges from 673 K to 823 K and from 923 K to 973 K, sulfidation is controlled by pore diffusion under Knudsen diffusion regime. This result shows that sulfidation has the influence of the change of pore radius of Fe₂O₃-SiO₂ particle at reduction.