Sulfur removal property of activated-char-supported Fe-Mo sorbents for integrated cleaning of hot coal gases

An integrated hot coal gas cleaning process is proposed with emphasis on simultaneous removal of multiple impurities including sulfur containing species, NOx precursors, mercury and tarry materials. Activated-char-supported sorbents were synthesized by gasifying Fe and Mo impregnated Chinese lignite coal in steam (15%, vol) at 1100 K for 15 min. Sulfur removal properties of the sorbent samples were examined by sulfidation experiments using simulated coal gases (with 4700 ppmv H2S and 470 ppmv COS) at a space velocity of 1000 h−1 using a fixed-bed quartz reactor at the temperature range of 673-873 K. The SEM with EDS and XRD were used to examine the physical and chemical changes in the sorbents during sulfidation. The active metal oxides components were dispersed in the char matrix as nano-size particles resulting in a high reactivity of the sorbents towards H2S and COS contained in coal gases. Under the conditions in this study, the sorbents can effectively remove H2S and COS from the simulated coal gases with high efficiency. Sulfur removal is influenced by the level of iron-loading. The presence of Mo along with Fe in the char-supported sorbents can significantly increase the desulfurization efficiency.