The effects of oxygen on the yields of the thermal decomposition products of catechol under pyrolysis and fuel-rich oxidation conditions

• Published in: Fuel (Guildford) Vol. 86; no. 16; pp. 2581 - 2595
• Main Authors: Thomas, Shiju, Ledesma, Elmer B., Wornat, Mary J.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.11.2007; Elsevier
• Subjects: Applied sciences; Catechol pyrolysis; Combustion of solid fuels; Combustion. Flame; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Oxygen; Theoretical studies. Data and constants. Metering; Thermal decomposition products; Catechol pyrolysis; Oxygen; Thermal decomposition products; Methane; Pyrolysis; Thermal decomposition; Combustion; Pyrocatechol; Solid fuel; Polycyclic aromatic compound; Gas chromatography; Phenol; Laminar flow; Styrene; Oxygen effect; Oxidation
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2007.02.003

In order to investigate the effects of oxygen on the distribution of thermal decomposition products from complex solid fuels, pyrolysis and fuel-rich oxidation experiments have been performed in an isothermal laminar-flow reactor, using the model fuel catechol ( ortho-dihydroxybenzene), a phenol-type compound representative of structural entities in coal, wood, and biomass. The gas-phase catechol pyrolysis experiments are conducted at a residence time of 0.3 s, over a temperature range of 500–1000 °C, and at oxygen ratios ranging from 0 (pure pyrolysis) to 0.92 (near stoichiometric oxidation). The pyrolysis products are analyzed by nondispersive infrared analysis and by gas chromatography with flame-ionization and mass spectrometric detection. In addition to an abundance of polycyclic aromatic hydrocarbons, catechol pyrolysis and fuel-rich oxidation produce a range of C 1–C 5 light hydrocarbons as well as single-ring aromatics. Quantification of the products reveals that the major products are CO, acetylene, 1,3-butadiene, phenol, benzene, vinylacetylene, ethylene, methane, cyclopentadiene, styrene, and phenylacetylene; minor products are ethane, propyne, propadiene, propylene and toluene. Under oxidative conditions, CO 2 is also produced. At temperatures <850 °C, increases in oxygen concentration bring about increases in catechol conversion and yields of C 1–C 5 and single-ring aromatic products—in accordance with increased rates of pyrolytic reactions, due to the enhanced free-radical pool. At temperatures >850 °C, catechol conversion is complete, and increases in oxygen bring about drastic decreases in the yields of virtually all hydrocarbon products, as oxidative destruction reactions dominate. Reactions responsible for the formation of the C 1–C 5 and single-ring aromatic products from catechol, under pyrolytic and oxidative conditions, are discussed.