Effects of low-temperature catalytic pretreatments on coal structure and reactivity in liquefaction. Technical progress report, January 1994--March 1994
Residues of two subbituminous coals from their liquefaction at 300-425{degrees}C were analyzed using cross-polarization magic-angle-spinning (CPMAS) and dipolar dephasing (DD) solid-state {sup 13}C NMR techniques. The DDMAS and CPMAS NMR analysis of a Montana subbituminous coal (DECS-9) indicate that it has 63-64% aromatic carbons among total carbons; 34-35% of the aromatic carbons are protonated carbons, and 23-24% of the aromatic carbons are oxygen-bound carbons, with the remaining 31-33% bound primarily to other carbon atoms. CPMAS {sup 13}C NMR spectrum of Wyodak subbituminous coal (DECS-8) is similar to that of Montana subbituminous coal (DECS-9). CPMAS {sup 13}C NMR of the residues from DECS-9 coal revealed that catechol-like structures and phenolic structures in the coal are thermally sensitive and diminish gradually with increasing temperature. The carbon aromaticity increased monotonically with increasing reaction temperature, whereas hydrogen aromaticity reached a maximum for residue from a 300{degrees}C run and then declines with further increase in temperature. The increase in carbon aromaticity is mainly driven by temperature, rather than by the adduction of aromatic solvents. DDMAS NMR analysis indicates that the degree of protonation of aromatic carbons decreased from 35% (for THF-extracted but unreacted DECS-9 coal) to 13% (for residue from a non-catalytic run) with increasing reaction temperature up to 375{degrees}C. DDMAS {sup 13}C NMR of the residues from DECS-8 Wyodak coal revealed that the degree of protonation of aromatic carbons (f{sub a}{sup ah}) is lower with the residues from catalytic liquefaction a 350{degrees}C.
- Research Organization:
- Pennsylvania State Univ., University Park, PA (United States). Dept. of Materials Science and Engineering
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC22-91PC91042
- OSTI ID:
- 10176265
- Report Number(s):
- DOE/PC/91042--9; ON: DE94017374
- Country of Publication:
- United States
- Language:
- English
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