DESULFURIZATION OF HOT COAL-DERIVED FUEL GASES WITH MANGANESE-BASED REGENERABLE SORBENTS .2. REGENERATION AND MULTICYCLE TESTS

In a previous paper, the reduction and sulfidation thermodynamic and k inetic characteristics of four manganese-based high-temperature desulf urization sorbents were investigated. A formulation, FORM4-A, which co nsisted of manganese carbonate, alundum, and bentonite exhibited the b est combination of capacity and reactivity; whereas, FORM1-A, which co nsisted of Mn ore, alundum, and dextrin exhibited the best combination of strength, capacity, and reactivity. In this paper the thermodynami c feasibility of regeneration is discussed. The kinetics of regenerati on of sulfided (loaded) pellets with air is studied in the 800-1000 de grees C temperature range. Repeated cycling of the leading sorbent for mulation (FORM4-A) was then conducted in a thermogravimetric apparatus (TGA), up to five consecutive cycles. One important finding was that the capacity of the pellets for sulfur pickup from fuel gas and the ki netics of reduction, sulfidation, and regeneration improved with recyc ling without compromising the strength. This appears to be a result of radial microcrack formation which reduced the solid-state diffusion p ath within the pellet.