Abstract
Liquefaction of Miike coal (Japanese bituminous coal) and Yallourn coal (Australian brown coal) were studied, and their results of conversion, yield of products and compositional distribution of oil products were compared with those of Taiheiyo and Forestburg coals (Japanese and Canadian sub-bituminous coals) which we have already reported. Experimental runs were carried out in a high pressure 500ml autoclave equipped with magnetic stirrer at 440°C under the initial hydrogen pressure of 85kg/cm2G in the presence of a red mudsulfur catalyst and 2 to 5 parts of tetralin or 2 to 3 parts of washing oil. The total conversion observed for Miike coal gave the highest value of 97wt%, while Yallourn coal gave a conversion of 92wt%, which was higher than that of sub-bituminous coals. (Table 3, Fig. 1) However, Miike coal produced a higher yield of SRC while the sub-bituminous coals yielded a greater amount of oil products (30-32wt%) than Yallourn coal (26wt%) and Miike coal (19wt%).
Changes in the contents of tetralin and naphthalene in the products were plotted against (oil-solvent)/solvent which was chosen as an index for evaluating the yield of oil products from different ranks of coals. (Fig. 2)
Linear relations for Miike and two sub-bituminous coals were observed, but the data of Yallourn coal did not fit the same correlation line. This suggests that a much larger amount of tetralin as a hydrogen donating agent is needed for liquefaction of Yallourn coal.
On the compositional analyses of oil products from different ranks of coals, it was observed that yields of phenol derivatives and methylsubstituted naphthalenes showed the highest value for Yallourn coal, and the above results from each coal were found to be correlated with oxygen and carbon contents in the original coals (Table 4, Figs. 3, 4), however, the concentrations of n-paraffins in the oil products for these four coals had no correlation with the ranks of coals. (Fig. 5)
We performed additional runs for liquefaction of Yallourn coal to investigate the effects of reaction time and solvent recycle mode operation on the composition of oil products. The results showed that hydrogen from tetralin was rapidly consumed in the early stages of reaction and the molecular hydrogen in the gas phase did not contribute to the liquefaction under the reaction conditions used. (Tables 5, 6, Fig. 6) The amount of phenol derivatives increased linearly with increasing recycle number, and it seemed to be accumulated in the recycle solvent. (Fig. 7)
