The paper discusses the production of calcium hydroxides with surface areas of 6-74 sq m/g, in an attempt to develop more reactive sorbents for SO2 capture during furnace injection. It was found that adding alcohol to the water of hydration yielded hydroxides with surface areas up to 40 sq m/g. The sorbents were produced using 'double hydration' and a mixture of water and methyl alcohol. When these sorbents were injected into the boiler, however, only marginal increases in SO2 capture were observed. The purpose of the research was to monitor structural changes in these sorbents during calcination in order to determine the reason for their relatively poor performance. For a given calcine and fixed conditions of calcination, the surface area decreased and median pore size increased with decreasing particle size in the 1.2-7.5 micrometer size range. This suggests that sintering advances more quickly in fine particles. For sorbents described here and using one precursor limestone, a correlation could be found between structural properties of Ca(OH)2 and nascent CaO. Increased surface area of Ca(OH)2 led to higher surface area of CaO after calcination at fixed conditions. The theoretical existence of an optimum combination of surface area and porosity of CaO was verified.

"EPA 600/D-89/204".