High-Temperature Desulfurizing Reaction with Cu-Containing Sorbents

Five kinds of Cu-containing solids, pure CuO, a physical mixture of CuO and Si0₂, CuO supported on Si0₂, CuO dispersed in a Si0₂matrix, and CuO supported on zeolite, were prepared as sorbents for high-temperature removal of H2S from the gas produced during coal gasification. These sorbents were subjected to successive sulfidationregeneration cycles, and their reaction behaviors were investigated by thermogravimetric analysis. Fresh, sulfided, and regenerated sorbents were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscope, and the BET surface area analysis. The reactivity of pure CuO, both in sulfidation and regeneration, was found to be lowest due to the formation of a dense sulfide layer during the sulfidation stage. The supported Cu sorbents had higher reactivities in both stages and showed no decline in reactivity through repeated sulfidation-regeneration cycles. The physically mixed sorbent exhibited almost the same reaction behavior as the supported ones. This finding suggests that physical mixing of CuO with inert solid is sufficient to increase the reactivity and lifetime of the sorbent. There is essentially no retardation effect of water vapor on the reactivity of the Cu-containing sorbents.