H2S REMOVAL FROM COAL-GAS AT ELEVATED-TEMPERATURE AND PRESSURE IN FLUIDIZED-BED WITH ZINC TITANATE SORBENTS .2. SORBENT DURABILITY

High-temperature high-pressure sulfur removal is considered as one of the key steps of the hot gas cleanup train of an IGCC process. Coal-derived gasifier gas contains sulfur gases (mainly H2S) which are converted to SO2 when the gas is combusted in the gas turbine, Cyclic sulfidation/regeneration tests were carried out in a pressurized fluidized bed reactor to remove H2S from a simulated coal gas to below 100 ppmv, using regenerable zinc titanate sorbents, The results, which were reported in part 1 of this paper, showed that the sorbent reactivity deteriorates in the cyclic process, In part 2, physical, chemical, and structural changes which the sorbents undergo in the cyclic tests are reported and discussed. The results of analyses conducted with ''fresh'' and ''used'' sorbents indicate that the loss of reactivity and sorbent deterioration is probably due to zinc migration to the surface of the sorbent particle during high-temperature high-pressure cyclic process.