Integrated Gasification Combined Cycle (IGSCC) and gasifier/molten carbonate fuel cell (MCFC) power plants employing hot-gas cleanup are two of the most promising advanced technologies for producing electric power from coal. A key component of these plants is a hot-gas desulfurization system employing regenerable sorbents capable of removing sulfur-bearing species from coal gasifier gas down to a few parts per million by volume. Fluidized-bed hot-gas desulfurization reactors offer advantages in IGCC systems compared to fixed- and moving-bed reactors because of their ability to control the highly exothermic regeneration involved. However, a durable attrition-resistant sorbent ranging from 100 to 300 (mu)m in size is needed. Therefore, a technique was identified for manufacturing zinc ferrite and zinc titanate sorbents with high long-term chemical reactivity and mechanical strength for fluidized-bed applications. These sorbents were tested in a bench-scale, high-temperature, high-pressure, fluidized-bed reactor system capable of operating up to 350 psig and 850(degrees)C. Zinc ferrite sorbents were found to be limited to 550(degrees)C and moderately reducing gases beyond which excessive sorbent weakening was observed due to chemical transformations. Zinc titanate sorbents, however, exhibited excellent sulfur capacity, regenerability, and attrition resistance at temperatures up to 750(degrees)C with virtually no zinc loss despite the highly reducing nature of simulated coal gases used. The commercial applicability of the sorbent manufacturing technique was demonstrated by producing 100 kg batches of zinc ferrite and zinc titanate. The sorbent manufacturing technique is scalable by a factor of 400 with commercially available equipment.
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