Reactivity and Characterization of Coal Macerals (Exinite, Vitrinite, and Inertinite)

摘要

Two bituminous coals have been separated into their three main maceral groups: exinite, vitrinite, and inertinite, using a modified float-sink technique which uses analytical density gradient centrifugation (DGC) to determine the appropriate density ranges. In this study the maceral concentrates were pyrolyzed in a vacuum and the resulting products collected and then characterized by gas chromatography mass spectrometry and by GC microwave plasma emission spectroscopy. The vacuum technique was chosen over the typical on-line pyrolysis-GCMS method for two reasons. First, experiments in this laboratory have shown that with the vacuum technique, secondary reactions such as aromatization of alicyclics is less likely to occur. Second, better quantitative data can be obtained with a batch type reaction scheme. In addition to characterization of thermal products, the chemical reactivity of these concentrates has been studied. Reactive hydrogens such as benzylic types have been determined from the reaction of the macerals with pyridine and iodine to form pyridinium iodides. It has been shown that the number of pyridinium iodides per 100 carbon atoms in the original coal decreases with increasing rank. Further studies have shown that these derivatized coals are activated toward oxidative solubilization using a reagent, alkaline silver oxide, which normally is quite ineffective in dissolving raw coals. In the results from the thermal and chemical reactions, similarities and differences have been noted which will be discussed later. Also, it should be emphasized that in this study we are examining maceral concentrates from the three main groups which are derived from the same coal. These coals were chosen to be representative of bituminous coals and not to be sapropelic coals where the chemistry may be more unusual due to the typically large exinite content. 1 figure, 1 table. (ERA citation 08:025341)