Product yields and kinetics from the vapor phase cracking of wood pyrolysis tars

Abstract

The homogeneous vapor phase cracking of newly formed wood pyrolysis tar was studied at low molar concentrations as a function of temperature (773–1,073 K), at residence times of 0.9–2.2 s. Tar conversions ranged from about 5 to 88%. The tars were generated by low heating rate (0.2 K/s) pyrolysis of ∼2 cm deep beds of sweet gum hardwood, and then rapidly conveyed to an adjacent reactor for controlled thermal treatment. Quantitative yields and kinetics were obtained for tar cracking and resulting products formation. The major tar conversion product was carbon monoxide, which accounted for over two‐thirds of the tar lost at high severities. Corresponding ethylene and methane yields were each about 10% of the converted tar. Coke formation was negligible and weight‐average tar molecular weight declined with increasing tar conversion. A first‐order distributed activation energy model more closely correlated tar conversion kinetics over a wider range of reaction conditions than did a single‐reaction model.

Pyrolysis behavior and kinetic study of phenol as tar model compound in micro fluidized bed reactor

“…2 that the formation of gas components (CH 4 and CO 2 ) is easier than that of H 2 and CO during pyrolysis of phenol. Besides, the activation energies for individual gas components, 30.87e145.2 kJ/mol, are lower than, but within the range of activation energies for thermal decomposition of tar from real biomass [41,42] or tar model compounds [11,43] reported in the literature. In this study the activation energies of four gas components all varied greatly rather than remain stable at different conversion fractions.…”

Energy and Exergy Analysis of High Temperature Agent Gasification of Biomass

“…β 1 , β 2 , β 3 , and β 4 are the stoichiometric coefficients of CO, CO 2 , H 2 and CH 4 , respectively. They were estimated using experimental data taken from the literature [24].…”

Modelling Underground Coal Gasification—A Review

“…The stoichiometric coefficients and kinetic parameters can be found from the work of Boroson and Howard [104].…”