Hydrogenolysis in coal liquefaction and pyrolysis: the relative importance of solvent radicals and free hydrogen atoms
Conference
·
OSTI ID:6323442
In this paper we wish to further support our contention that a significant part of the structural fragmentation occuring during coal liquefaction is not ''spontaneous'', but results from a previously undocumented fundamental reaction, '' radical-hydrogen-transfer'' (RHT), to aromatic positions bearing aliphatic (or ether) linkages in the coal structures (reaction 1). It is no longer at issue whether alternatives to thermal scission of inherently weak bonds exist under donor solvent coal liquefaction conditions: The observed cleavage of very strong alkyl-aryl bonds in hydroaromatic media, at 400C, in the absence of H2 pressure, on coal liquefaction time scales, (reaction 2) has demonstrated that what are formally defined as hydrogenolyses do take place under conditions where free hydrogen atoms have been thought to be unimportant. The fundamentally intriguing and possibly technologically important question that remains is whether or not this cleavage simply involves the ipso addition of free hydrogen atoms, and if does not, then by what mechanism does it take place. In order to help answer the above question, we wish to present results that (1) demonstrate the relative importance of free hydrogen atoms and solvent ''hydrogen-carrier radicals'' for bond scission in the donor solvent system most likely (of those systems generally studied) to generate ''free'' hydrogen atoms, and (2) suggest the relative importance of the two transfer modes for solvent systems that are much less likely to generate free hydrogen atoms (and not coincidentally are better coal liquefaction solvents). 16 refs., 1 tab.
- Research Organization:
- SRI International, Menlo Park, CA (USA). Chemical Physics Lab.
- DOE Contract Number:
- AC03-79ER10483
- OSTI ID:
- 6323442
- Report Number(s):
- CONF-850942-48; ON: DE86006367
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
01 COAL, LIGNITE, AND PEAT
010405* -- Coal
Lignite
& Peat-- Hydrogenation & Liquefaction
CARBONACEOUS MATERIALS
CHEMICAL BONDS
CHEMICAL REACTIONS
CLEAVAGE
COAL
COAL LIQUEFACTION
COMPARATIVE EVALUATIONS
CRYSTAL STRUCTURE
DECOMPOSITION
ENERGY SOURCES
FOSSIL FUELS
FUELS
HYDROGEN TRANSFER
LIQUEFACTION
MATERIALS
MICROSTRUCTURE
ORGANIC SOLVENTS
PYROLYSIS
RADICALS
SOLVENTS
STRUCTURAL MODELS
TEMPERATURE DEPENDENCE
THERMOCHEMICAL PROCESSES
010405* -- Coal
Lignite
& Peat-- Hydrogenation & Liquefaction
CARBONACEOUS MATERIALS
CHEMICAL BONDS
CHEMICAL REACTIONS
CLEAVAGE
COAL
COAL LIQUEFACTION
COMPARATIVE EVALUATIONS
CRYSTAL STRUCTURE
DECOMPOSITION
ENERGY SOURCES
FOSSIL FUELS
FUELS
HYDROGEN TRANSFER
LIQUEFACTION
MATERIALS
MICROSTRUCTURE
ORGANIC SOLVENTS
PYROLYSIS
RADICALS
SOLVENTS
STRUCTURAL MODELS
TEMPERATURE DEPENDENCE
THERMOCHEMICAL PROCESSES