Liquefaction behavior of separated coal macerals

In a joint program, groups at Amoco Oil and Argonne National Laboratory have elucidated the behavior of very pure coal macerals under liquefaction conditions. Macerals are microscopic distinct components of the organic matter in coals that differ in their chemical and physical properties. A new method, continuous flow density gradient centrifugation, was used to separate an Argonne Premium Coal Sample into its three main maceral groups, vitrinite, which is derived from wood, liptinites, which are derived from a number of plant sources rich in hydrogen arid, finally, inertinites, which are in part fossil charcoal. In the liquefaction studies, each pure maceral was heated with a hydrogen-rich solvent and the products were analyzed. The liquefaction yields decreased in the order: liptinite > vitrinite > inertinite. The liptinite provided the most oil, a material that is similar to crude oil, but also contains higher molecular weight products with large amounts of oxygen, sulfur, and nitrogen. The work showed that the macerals do not react synergistically during liquefaction. Further, the least reactive inertinites, which constitute 15% of this coal, are not converted into desirable products. Therefore, inertinite removal prior to liquefaction can potentially improve process efficiency. This study furthered our understanding of liquefactionmore » behavior of individual macerals, determined differences in product characteristics, and determined that interactions among the different maceral groups during liquefaction do not occur.« less