To remove hydrogen sulfide from hot coal gases at middle temperature, the various sorbents were prepared by precipitation or co-precipitation method. The cobalt and nickel-based sorbents promoted with alumina showed good regeneration properties during multiple cycles. The roles of each component in the sulfidation and regeneration were discussed with the results from XRD and TPD.

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To simultaneously remove hydrogen sulfide and ammonia from hot coal gases, the ammonia decomposition abilities of various metal oxide catalysts were tested in the absence/presence of hydrogen sulfide, at 650°C. Cobalt oxide, molybdenum oxide, and nickel oxide have high ammonia decomposition abilities ([95%) in the absence of hydrogen sulfide, but such abilities rapidly decreased during the reaction in the presence of hydrogen sulfide. To improve the simultaneous removal abilities of metal oxides, Zn-based catal sorbents were prepared via impregnation with various metals, such as cobalt, nickel, and molybdenum, on zinc oxide. The CZ-30 (promoted with 30 wt% cobalt oxide on zinc oxide) and NZ-30 (promoted with 30 wt% nickel oxide on zinc oxide) catal sorbents showed excellent sulfur removal capacities, which, calculated until the breakthrough point, were 0.35 and 0.39 g S/g catal sorbent, respectively, while MZ-30 promoted with molybdenum showed a low sulfur removal capacity of 0.08 g S/g catal sorbent. The ammonia decomposition ability of CZ-30, however, increased more than 18 times compared with Co 3 O 4 , whose ammonia decomposition ability was more than 95% until 465 min, even though the ammonia decomposition ability of NZ-30 sharply decreased after 30 min. The CZ catal sorbent is a good candidate for the simultaneous removal of ammonia and hydrogen sulfide.

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