Effectiveness of natural, commercial, and modified calcium-based sorbents as H2S removal agents at high temperatures

Coat gas desulfurization is one of the most important gas cleaning steps pr evious to its use in a gas turbine in integrated gasification combined cycl e (IGCC) systems. In this work, 12 different calcium based materials, both natural, commercial and modified with several additives, were tested in a d rop tube reactor as potential H2S removal agents at high temperatures and r educing conditions. Three limestones and a dolomite were selected by their different natures and reactivities. The commercial products used were calci um hydroxide, calcium acetate (CA), and calcium magnesium acetate (CMA). Mo re over,two limestones of different nature and reactivity were used as star ting material to prepare several calcium hydroxides modified with calcium l ignosulfonate (LGS) and calcium acetate (CA). An important improvement in s ulfur removal respect to the sorbent prepared without additives was achieve d when using the modified sorbents. However, the highest sulfur removal was obtained with CA and CMA sorbents due to their ability to form highly poro us cenospheres of thin watts. H2S capture up to near the thermodynamic equi librium was achieved with dry-injection of the CA and CMA at furnace gas te mperatures of about 1000 and 800 degrees C, respectively, a Ca/S molar rati o of 2, and 0.8 s of residence time.