Reactivity of target compounds for chemical coal desulfurization. Technical report, 1 December 1993--28 February 1994

Abstract

This project seeks to identify representative organosulfur compounds which are removed by coal desulfurization reactions. Demineralized coals from the Illinois Basin Coal Sample Program are solvent extracted and the extracts fractionated to separate and concentrate organosulfur compounds for analysis by Gas Chromatography/Mass Spectroscopy. After sulfur compounds are characterized, the parent extracts will be subjected to reactions previously shown to reduce the organic sulfur content of Illinois coals, fractionated and again analyzed for organosulfur content to determine which compounds reacted during the chemical treatment. The original coal will be subjected to chemical desulfurization, extraction, fractionation and analysis in order to correlate changes in organic sulfur content of the coal with reactions of specific sulfur compounds. These compounds can thus be reliably considered as target molecules for the next generation of desulfurization processes. During this quarter, work continued on developing efficient methods to isolate and analyze sulfur-rich coal extract fractions by GC/MS. Since only relatively non-polar compounds can be analyzed, pyridine extracts must be fractionated. Direct extraction of several coals with toluene is quicker but did not give as much toluene soluble material as fractionation of pyridine extracts and is thus not suitable for preparation of representative analytical samples. The authors observe that most IBC sample program coals contain elemental sulfur due to oxidation of pyrite. There is less elemental sulfur in IBC-101 than in other Herrin coals. This coal was washed in a preparation plant to reduce pyrite concentration. Since elemental sulfur slowly reacts to produce organosulfur compounds in coal during storage or handling, this suggests that early removal of pyrite can reduce formation of these hard to remove compounds.