Kinetics of the thermal decomposition and isomerization of pyrazine (1,4 diazine)
- Univ. of Sydney (Australia). Dept. of Physical and Theoretical Chemistry
The isomerization and decomposition of pyrazine have been studied over the temperature range 1,200--1,480 K. The major products of decomposition were found to be acetylene and HCN, with cyanoacetylene and acrylonitrile also being significant products, although lower yields of these products were observed. The decomposition has been successfully modeled using a free radical mechanisms, with the major chain carriers being CN radicals and H atoms. The initiation reaction was found to be C{single_bond}H bond fission, to yield H atoms and pyrazyl radicals. Kinetic modeling allowed the rate of initiation to be determined, yielding a first-order rate constant given by the expression k = 10{sup 15.7} exp({minus}96.5 kcal/mol/RT) s{sup {minus}1}. The importance of CN radicals as chain carriers appears to be a significant difference in the decomposition of the dizziness compared with pyridine or 2-picoline. Accompanying the decomposition of pyrazine was the isomerization of pyrazine to pyrimidine. By kinetic modeling, the isomerization of pyrazine to pyrimidine was found to occur via a fulvenelike intermediate. The rate and mechanism of the isomerization are analogous to the isomerization of fulvene to benzene described by Melius and Miller. The thermal reactions of these species are being studied because of their relevance to the mechanism of formation of NO{sub x} through the oxidation of fuel-bound nitrogen (FBN) in coal during the combustion of coal and heavy fuels.
- OSTI ID:
- 93237
- Report Number(s):
- CONF-940711--
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
02 PETROLEUM
ACTIVATION ENERGY
CHEMICAL REACTION KINETICS
CHEMICAL REACTION YIELD
COAL
COMBUSTION KINETICS
EXPERIMENTAL DATA
ISOMERIZATION
MATHEMATICAL MODELS
NITROGEN OXIDES
PYRAZINES
PYRIMIDINES
PYROLYSIS
PYROLYSIS PRODUCTS
RESIDUAL FUELS
SYNTHESIS
TEMPERATURE DEPENDENCE