Regenerable Sorbent Pellets for the Removal of Dilute H2S from Claus Process Tail Gas

Abstract

The Claus process is the most important sour gas sweetening process to recover elemental sulfur from H2S, which is present in raw natural gas and byproduct gases from crude oil refineries. However, current methods for treating the tail gas of the Claus process are expensive and often not environmentally friendly. Various sorbents have been reported for H2S capture, but few reports focus on the pellet design, formation, and testing. In this study, we developed a pelletization method to prepare sorbent pellets with high sulfur capacity and good regenerability for the removal of dilute H2S from Claus process tail gas. The sorbent pellets consisted of mixed metal oxides of Cu, Mg, and Al with fumed silica as the binder and were characterized using various techniques, including X-ray and electron diffraction, N2 sorption, and scanning and transmission electron microscopy. The H2S sorption capacity was evaluated by breakthrough experiments at 150 °C in a gas stream consisting of 100 ppm of H2S in N2. The optimized sorbent pellets gave a stable breakthrough sulfur capacity of ∼5 mmol/g over three cycles of sulfidation and regeneration. They exhibited an average radial crush strength of 154 ± 40 N.