DESULFURIZATION OF ILLINOIS NO-6 BITUMINOUS COAL VIA REDUCTIVE CARBOXYLATION IN ABSOLUTE ETHANOL

This study detailed the sulfur removal from Illinois No. 6 bituminous coal through reductive carboxylation in absolute ethanol. Maximum desu lfurization (68%) occurred at 300 degrees C using 10 g of sodium hydro xide, 500 mt of ethanol, and 10 g of 250/325 Tyler mesh coal. Sulfur r emoval increased with an increase in reaction temperature, lower base concentration (10 g vs 20 g of NaOH), and the use of carbon dioxide. T he improved desulfurization of reactions which used carbon dioxide was the result of selective carboxylation of organosulfur compounds. The mass recovery of original coal samples ranged from 77% to 91%, with th e lower values occurring at higher temperatures. Conversely, heat cont ent values increased as the temperature was increased. Elemental and i nfrared analyses revealed that hydrogenation and loss of C-O functiona l groups, as opposed to solvent incorporation, were the main causes. E lemental analyses of selected residues (acid-washed, moisture-free: AW MF) and acids recovered from basic solutions indicated that hydrogenat ion of coal had occurred. The degree of hydrogenation was found to inc rease with reaction temperature. The O/C ratios of black acids were hi gher than those of AWMF residues, which supported the theory that carb oxylic acids were removed from the products. Most of the sulfur that w as removed from the coal samples remained soluble in water and was not recovered. Solubilization occurred through a displacement reaction wi th sodium and through demineralization in 10% hydrochloric acid. The r emaining sulfur was either lost during product separation or recovered in the acid fraction. The acid fractions were formed from carboxylati on of organic precursors, some of which contained sulfur.