Pyrolysis of coal maceral concentrates under pf-combustion conditions (II): changes in heteroatom partitioning as a function of rank

Differences between maceral types with respect to heteroatom partitioning during pyrolysis under conditions representative of pf-combustion have been investigated. Pyrolysis experiments have been carried out in a wire-mesh reactor; maceral concentrates and whole coals have been heated at 5000 degrees C s(-1) to 1500 degrees C, in atmospheric pressure He. The proportion of N-retention in chars was found to increase from about 10 to 60% in the 75-95% elemental-Ci range, irrespective of maceral composition. However, char-N retention by inertinites was slightly less than that for vitrinites; retention by liptinites was clearly less than that for vitrinites. The general trend for sulfur retention was similar: for vitrinite and inertinite concentrates, sulfur retention increased from about 30 to 60% over the 72-95% elemental-C content interval. Once again, retention in liptinites was considerably lower-between 5 and l5%-for the three samples used in the study. Ash contents of the present set of samples suggest that it would not be realistic to discuss the present set of sulfur retention data in terms of organic sulfur alone. The work outlined above lead to several tentative conclusions, pinpointing areas where new structural work is required. (C) 1998 Elsevier Science Ltd. All rights reserved.