Pathways in coal thermolysis: a theoretical and experimental study with model compounds
Fundamental aspects of coal thermolysis were investigated, including how the chemical structures of aromatics, hydroaromatics, and alcohols affect their reactivities as hydrogen donors and acceptors in coal processing. The susceptibilities of substructural entities in coals to fragmentation via a number of thermal pericyclic and free radical mechanisms were probed, as were the factors governing relative reactivities within series of such coal model compounds. The theoretical part of the work applied perturbation molecular orbital (PMO) and frontier orbital theories, in conjunction with ..pi..- and pseudo-..pi.. MO's, to the study of model compound reactivity. This enabled prediction of reactivity patterns of H-donors, H-acceptors and coal-like structures as functions of their ..pi..- and sigma-bond configurations, including heteroatomic effects. Experimentally, the liquid phase reactions of the coal model compound PhOCH/sub 2/Ph (Benzyl phenyl ether, BPE) were detailed for the first time in each of four hydronaphthalene H-donor solvents in the temperature range 220/sup 0/ to 300/sup 0/C. The thermolysis of BPE exhibited a pronounced dependence on solvent structure, both with respect to product selectivities and reaction kinetics. BPE thermolysis pathways were delineated as involving (a) rearrangement, leading to isomerization, (b) hydrogenations, leading ultimately to PhOH and PhCH/sub 3/ products, and (c) addition reactions, engendering heavy products. Pathways (b) and (c) are competitive and, in each, self-reactions of BPE-derivatives vie against reactions between these and the donor solvent. Of the detailed free radical and pericyclic reaction mechanisms postulated, the latter rationalized many more facets of the BPE results than the former. The theoretical and experimental results were appraised against previous coal thermolysis literature.
- Research Organization:
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
- DOE Contract Number:
- AM01-76EI02295
- OSTI ID:
- 7024365
- Report Number(s):
- MIT-EL-82-007; ON: DE83002481
- Resource Relation:
- Other Information: Thesis. Submitted by I.A. Ekpenyong. Portions of document are illegible
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
COAL
PYROLYSIS
ADDUCTS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COMPARATIVE EVALUATIONS
ETHERS
HYDROGENATION
ISOMERIZATION
ORGANIC SOLVENTS
RADICALS
STRUCTURAL MODELS
CARBONACEOUS MATERIALS
DECOMPOSITION
ENERGY SOURCES
FOSSIL FUELS
FUELS
KINETICS
MATERIALS
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
REACTION KINETICS
SOLVENTS
THERMOCHEMICAL PROCESSES
010406* - Coal & Coal Products- Pyrolysis & Cracking- (-1987)