SULFATION OF AL2O3 IN FLUE-GAS DESULFURIZATION BY CUO/GAMMA-AL2O3 SORBENT

Deep sulfation of alumina support in flue gas desulfurization by CuO/gamma-Al2O3 sorbent causes a detrimental effect on stability and regeneration of the sorbent since regeneration of sulfated sorbent requires higher temperatures. To define the sulfation characteristics of alumina support in CuO/gamma-Al2O3, the effects of temperature, CuO loading, and addition of NaCl on sulfation of alumina support have been determined in a thermobalance reactor. The sulfation degree of alumina support in terms of the amount of sulfate ions present on the support can be classified into three types (surface, slightly deep, and bulk sulfations) as a function of reaction temperature and CuO loading. Surface sulfation (sulfate ions < 2.0 x 10(18) ions/m2) occurs at CuO loading between 2 and 11 wt % at reaction temperature 250-350-degrees-C, slightly deep sulfation (2.0 x 10(18) ions/m2 < sulfate ions < 3.4 x 10(18) ions/m2) occurs with the loading below 4 wt % at 350-600-degrees-C, and bulk sulfation (3.4 x 10(18) ions/m2 < sulfate ions) occurs at the loading above 6 wt % at 450-600-degrees-C. The bulk sulfation of alumina occurs in the presence of SO3 decomposed from CuSO4. The main product of deep sulfation is Al2(SO4)3 which is identified by the X-ray diffraction peak at 2theta = 25.4. With an addition of 5 wt % NaCl, bulk sulfation occurs at lower temperature by 50-degrees-C and lower CuO loading by 2 wt % CuO.