Molecular accessibility in oxidized and dried coals. Quarterly report

Technical Report · Thu Sep 01 04:00:00 EDT 1994

OSTI ID:10107629

Kispert, L D

The objective of this research project is to determine the molecular and structural changes that occur in swelled coal as a result of oxidation and moisture loss both in the presence and absence of light using the newly developed EPR spin probe method. The proposed study will make it possible to deduce the molecular accessibility distribution in swelled, oxidized APCS coal for each rank as a function of (1) size (up to 6 nm) and shape, (2) the relative acidic/basic reactive site distributions, and (3) the role of hydrogen bonding as a function of swelling solvents. The advantage of the EPR method is that it permits molecules of selected shape, size and chemical reactivity to be used as probes of molecular accessible regions of swelled coal. From such data an optimum catalyst can be designed to convert oxidized coal into a more convenient form and methods can be devised to lessen the detrimental weathering processes. The observed data for the APCS coals studied to date can be explained in terms of four different processes: one, disruption of weak hydrogen bonds which protect or isolate the interconnected micropore system; two, disruption of weak hydrogen bonds which protect individual micropores; three, the competition of pyridine for the active sites capable of establishing hydrogen bonds or the poisoning of active sites; four, disruption of stronger hydrogen bonds within the macromolecular structure which cause an opening of the structure. The contributions of each of these factors to the spin probe retention with increasing concentrations of pyridine varying up to 5% pyridine are examined. At concentrations above 5% pyridine, the first factor becomes less significant, and variations in the others require greater changes in pyridine concentration.

• Research Organization: Alabama Univ., University, AL (United States). Dept. of Chemistry
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: FG22-93PC93202
• OSTI ID: 10107629
• Report Number(s): DOE/PC/93202--4; ON: DE95005200; BR: AA1525050
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
010600
BITUMINOUS COAL
DRYING
ELECTRON SPIN RESONANCE
EXPERIMENTAL DATA
LIGNITE
MORPHOLOGICAL CHANGES
OXIDATION
PORE STRUCTURE
PROGRESS REPORT
PROPERTIES AND COMPOSITION
SURFACE PROPERTIES
SWELLING