The effects of electrochemical hydrogenation on coal structure: chemical and macromolecular changes

A set of five coals have been electrochemically hydrogenated and changes to the chemical structure were monitored by elemental analysis and NMR. It wa s thought that the elemental analysis gave spurious results due to possible hydrogen trapping. The NMR clearly showed a decrease in aromatic material and the creation of aliphatics. Changes to the macromolecular structure fol lowing hydrogenation were monitored by measuring changes in: the amount of pyridine soluble material; the amount of volatile material; decrease in gla ss transition temperatures; and in solvent swelling. The increase in the am ount of aliphatic material correlated well with the change in the amount of soluble material and decrease in glass transition temperature. A less perf ect correlation was noted between the amount of aliphatic material and the amount of volatile material and no correlation was noted between increase i n aliphatics and solvent swelling. (C) 2000 Elsevier Science Ltd. All right s reserved.