A review of thermolysis studies of model compounds relevant to processing of coal

Technical Report · Sun Nov 01 00:00:00 EST 1987

OSTI ID:5910380

Poutsma, M L

The bond breaking, bond making, rearrangement, and hydrogen transfer reactions that occur in coal at approx.350 to 1000/sup 0/C largely involve transient free radicals as reactive intermediates. However, the structural complexity and heterogeneity of coal has hampered development of detailed reaction mechanisms at the molecular level. Studies of the thermolysis and hydrogenolysis of model compounds, chosen to represent individual structural units in coal, provide very useful input toward that goal. These are selectively and critically reviewed in this report. Emphasis is placed on recent quantitative studies of product composition and kinetic behavior that have been carried out at low extents of conversion. The classes of organic structures covered are alkanes; aromatic hydrocarbons; alkylaromatics; ..cap alpha..,..omega..-diphenylalkanes, Ph(CH/sub 2/)/sub n/Ph (n = 0 to 4), and their analogs with a CH/sub 2/ group replaced by O, S, or NH; hydroaromatics; phenols, alkylphenols, and aryl ethers; and carbonyl compounds. Thermal behavior of pure model compounds is reviewed along with its perturbation by added hydroaromatics or molecular hydrogen. Structure-reactivity patterns within each class are illustrated whenever possible. Coverage is divided arbitrarily into a ''low-temperature regime,'' approx.300 to 450/sup 0/C and a ''high-temperature regime,'' approx.600 to 900/sup 0/C dominated by gas-phase studies. Extensive use is made of the methodology of thermochemical kinetics. Several discrepancies between literature data or suggested mechanisms and predictions based on currently accepted thermochemistry of free radicals and kinetic expressions for prototypical elementary free radical reactions are pointed out. Inversely, certain mechanistic hypotheses offered herein require experimental evaluation. 303 refs., 19 tabs.

• Research Organization: Oak Ridge National Lab., TN (USA)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 5910380
• Report Number(s): ORNL/TM-10637; ON: DE88003690
• Resource Relation: Other Information: Portions of this document are illegible in microfiche products. Original copy available until stock is exhausted
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
CHEMICAL BONDS
CLEAVAGE
COAL
PYROLYSIS
STRUCTURAL MODELS
CHEMICAL REACTIONS
REVIEWS
ALKANES
AROMATICS
BENZENE
BIBENZYL
CARBONYLS
CHEMICAL REACTION KINETICS
COAL TAR
CONTROLLED ATMOSPHERES
CRESOLS
ETHANE
ETHERS
HEXANE
HYDROGEN TRANSFER
HYDROGENATION
MOLECULAR STRUCTURE
NAPHTHOLS
PHENOL
RADICALS
REACTION INTERMEDIATES
TETRALIN
THERMAL CRACKING
THERMOCHEMICAL PROCESSES
THERMODYNAMICS
VOLATILE MATTER
ATMOSPHERES
CARBONACEOUS MATERIALS
CRACKING
CRYSTAL STRUCTURE
DECOMPOSITION
DOCUMENT TYPES
ENERGY SOURCES
FOSSIL FUELS
FUELS
HYDROCARBONS
HYDROXY COMPOUNDS
KINETICS
MATERIALS
MATTER
MICROSTRUCTURE
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
OTHER ORGANIC COMPOUNDS
PHENOLS
REACTION KINETICS
TAR
010409* - Coal
Lignite
& Peat- Pyrolysis & Carbonization- (1987-)