The dual role of oxygen functions in coal pretreatment and liquefaction: Crosslinking and cleavage reactions. Fifth quarterly report, April 1, 1992--June 30, 1992
Preparation of ion-exchanged (including barium, calcium and potassium) demineralized Zap and Wyodak has been completed. Both vacuum dried and moist samples were prepared, using procedures described previously. The modified samples were subjected to functional group analysis as KBr pellets with FT-IR, and programmed pyrolysis analysis with TG-FTIR. Liquefaction experiments of these samples were also performed and products were analyzed. The data show that both the pyrolytic tar and liquefaction yields decrease with the extent of ion-exchange, i.e., in the order of (demineralized) > (ion-exchanged at pH 8) > (ion-exchanged at pH 12.5). For the pyrolysis of vacuum dried samples, the tar yield was higher for the potassium-exchanged coals than the calcium and barium-exchanged samples, suggesting that bivalent cations tighten the coal structure by cross-linking coal fragments and make it more difficult for tar molecules to escape. The liquefaction results show that the potassium-exchanged samples have higher liquefaction yields (especially asphaltenes) than for the barium- and calcium-exchanged samples. This can probably be attributed to the same reason for the high pyrolytic tar yield, i.e., that bivalent cations can serve as a cross-linking agents to tighten the coal structure. Remoisturization of vacuum dried Zap and Wyodak was done in the attempt to understand if moisture uptake for low rank coals is a reversible process and to see if moisture influences the role of the cations. Preliminary results show that the moisture content can reach that of the raw samples by remoisturization for Zap, but not for Wyodak. Furthermore, the chemical structure of the coal samples seems to have been changed by remoisturization, since different C0{sub 2} evolution behaviors were observed.
- Research Organization:
- Advanced Fuel Research, Inc., East Hartford, CT (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC22-91PC91026
- OSTI ID:
- 10104114
- Report Number(s):
- DOE/PC/91026-T5; ON: DE93004931
- Resource Relation:
- Other Information: PBD: [1992]
- Country of Publication:
- United States
- Language:
- English
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