Analysis of the Average Poly-Cyclic Aromatic Unit in a Meta-Anthracite Coal Using Conventional X-ray Powder Diffraction and Intensity Separation Methods

Abstract

X-ray characterizations of coals and coal products have occurred for many years. Hirsch and Cartz measured the diffraction from several coals over the reciprocal space region from s = 0.12 {angstrom}{sup -1} to 7.5 {angstrom}{sup -1} where s = (4{pi}/{lambda}) sin{Theta}. In these studies, a 9 cm powder camera was used to study the high angle region, and a transmission type focusing camera equipped with a LiF monochromator was used for the low angle measurements. They reported that the height of the graphene peak measured for each coal is proportional to the % carbon in the coals. Hirsch also suggested that the ontyberem anthracite has a lamellar diameter of ca. 16 {angstrom} corresponding to an aromatic lamellae of ca. C{sub 87}. For coals with lower carbon content, Hirsch proposed much smaller lamellae; C{sub 19} for a coal with 80% carbon, and C{sub 24} for a coal with 89% carbon. The subject coal for this study is a meta-anthracite which was derived from the Portsmouth, RI mine. The Narragansett Basin contains anthracite and meta-anthracite coals of Pennsylvanian Age. The Basin was a techtonically active non-marine coal-forming basin which has been impacted by several tectonic events. Because of the importance placed bymore » coal scientists no correctly characterizing the nature of the micro-level structural cluster(s) in coals and because of improvements in both x-ray experimentation capabilities and computing power, we have measured the x-ray diffraction and scattering produced from irradiation of this meta-anthracite coal which contains about 94% aromatic carbon. The goal of our study is to determine the intra-planar, and where possible, inter-planar structural details of coals. To accomplish this goal we have utilized the methods normally used for the molecular analysis of non-crystalline condensed phases such as liquids, solutions, and amorphous solids. Reported herein are the results obtained from the high angle x-ray analysis of this coal.« less