A sulfur removal and disposal process through H2S adsorption and regeneration: Breakthrough behaviour investigation

The breakthrough behaviours of H2S adsorption in a fixed-bed reactor of iron oxide based adsorbent under elevated pressures were studied. The effects of variations in superficial gas velocity from 0.09 to 0.26 m/s, H2S feed concentration from 0.5% to 6% (v/v), the operating pressure from 405 to 5070 kPa absolute, and the height of the fixed-bed from 11.7 to 24.5 cm on the breakthrough curves and sulfur loading capacity were investigated. It was found that the shape of the breakthrough curves depends on the superficial velocity and the inlet H2S concentration in gas streams. Under both higher superficial velocity and higher inlet H2S concentration, the shape of the breakthrough curve becomes steeper, and vice versa. The sulfur loading capacity decreases as the superficial velocity and the inlet H2S concentration increase, but it increases as the bed height increases. The change of operating pressure does not have a significant effect on the shape of the breakthrough curve or sulfur loading of the adsorbent. The pressure drop across the bed follows the Ergun equation. The investigation was also extended to the use of the regenerated adsorbents. An empirical equation of exponential function can be used to describe the breakthrough curves. This work provides useful data for the adsorption tower design and process optimization.

Research highlights▶ The H2S breakthrough curve of the iron oxide based adsorbent is a non-S type. ▶ H2S flux through the bed determines the shape of breakthrough curves. ▶ Operating pressure has no significant impact on breakthrough behaviour. ▶ An empirical equation is used to predict the breakthrough curves. ▶ The Ergun equation can predict pressure drop across the iron oxide adsorbent bed.