石炭の予熱による共炭化被修飾性の変化

抄録

Cocarbonization properties of some coals with petroleum derived pitches (A240 or HA240) were examined after their preheat treatment at 200-400°C to reveal the reactivities of coals in the precarbonization and its influences on their cocarbonization susceptibilities against the additive. When two paticular coals of Zontag Vlei and Metla of the similar rank, the susceptibility of the former coal being much higher than that of the latter without any pretreatment were compared, the latter coal lost its susceptibility at much lower temperature than the former, although both coals did completely at 410°C where the respective chars were produced.
The pretreatment such as de-mineralization and o-alkylation, which had been found effective to improve the cocarbonization susceptibility of the latter coal, increased markedly the stability of its cocarbonization susceptibility against the preheat treatment.
Some other coals exhibited their respective precarbonization, reactivity to deteriorate the susceptibility, the extent of deterioration appearing to correspond to the cocarbonization behavior approximately but not exactly according to their ranking.
An Australian brown coal exhibited interesting behaviors to exhibit better cocarbonization susceptibility in a very limited temperature range of the preheat treatment, where the homogeneity of isotropic appearance of the coke was very much improved, indicating that the coal was dissolved or solvolyzed better in the additives after the preheat treatment.
Some analytical studies on the preheat treated coals, evolved gases and weight decrease during the preheat treatment suggest that the reactivities of oxygen functionality are related to the above behaviors. Its higher condensation reactivity tends to lead to the deterioration of cocarbonization susceptibility, however the adequate removal of oxygen functionalities in the brown coal by the preheat treatment improves its cocarbonization susceptibility probably due to the decarboxylation.