Cellulose and red pine were thermally decomposed in water at 200°C in order to clarify the origin and formation of coal. The gaseous and water-soluble products were analyzed by GC and 1H-NMR, while the structural consideration of the water-insoluble solid products was performed by elemental analyses, CP/MAS 13C-NMR and functional group analyses. Morwell brown coal and Morwell coalified log were also analyzed by the same methods.
Cellulose was gradually converted at 200°C into water, carbon dioxide, water-solubles and water-insoluble brownish materials. The product distribution did not change after 20hours. The 13C-NMR spectra of the brownish residues after 20hours were similar to that of Morwell brown coal, which indicated that polycyclic aromatic structures should be formed from cellulose during the hydrous pyrolysis at 200°C. The 13C-NMR spectra of the hydrous pyrolysis residues (50hr and 100hr) of red pine were similar to that of Morwell coalified log.
The partial model structures of the hydrous pyrolysis residues (50hr), Morwell brown coal, and Morwell coalified log were obtained from the analytical data as shown in Fig. 8. The results showed that the hydrous pyrolysis at 200°C could transform cellulose and wood to brown coal-like materials in only twenty hours.
