W. Mojtahedi et J. Abbasian, H2S REMOVAL FROM COAL-GAS AT ELEVATED-TEMPERATURE AND PRESSURE IN FLUIDIZED-BED WITH ZINC TITANATE SORBENTS .2. SORBENT DURABILITY, Energy & fuels, 9(5), 1995, pp. 782-787
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-de
rived gasifier gas contains sulfur gases (mainly H2S) which are conver
ted to SO2 when the gas is combusted in the gas turbine, Cyclic sulfid
ation/regeneration tests were carried out in a pressurized fluidized b
ed reactor to remove H2S from a simulated coal gas to below 100 ppmv,
using regenerable zinc titanate sorbents, The results, which were repo
rted in part 1 of this paper, showed that the sorbent reactivity deter
iorates in the cyclic process, In part 2, physical, chemical, and stru
ctural changes which the sorbents undergo in the cyclic tests are repo
rted and discussed. The results of analyses conducted with ''fresh'' a
nd ''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.