Oxidation kinetics of eucalyptus chars produced at low and high heating rates

M. Guerrero*, M.P. Ruiz, A. Millera, M.U. Alzueta, R. Bilbao

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

12 Citations (Scopus)

Abstract

An experimental and kinetic study of the oxidation of eucalyptus chars obtained by pyrolysis at 900 °C with low and high heating rates (LHR and HHR, respectively) has been performed. Oxidation experiments were carried out in a quartz reactor with an inlet oxygen concentration ranging from 100 to 1000 ppmv in a nitrogen flow, a temperature of 900 °C, and a flow rate of 1000 mL min−1 (STP). In order to analyze the temperature influence on the process and to obtain the process activation energy, char oxidation tests were also performed in the 650–900 °C temperature range, for a given oxygen concentration of 500 ppmv. Kinetic parameters were derived from the oxidation reaction data, which fitted properly the macroscopic model of type I in regime II. The reaction orders with respect to the oxygen concentration were found to be 0.58 and 0.66 for LHR and HHR chars, respectively. In both cases, it was observed a “break” in the Arrhenius plot. At low temperatures (650–800 °C), the activation energy was similar for the oxidation of both chars, in the 35–45 kJ mol−1 range. However, in the high temperature range (800–900 °C), the activation energy was 100 kJ mol−1 for the LHR char oxidation and 60 kJ mol−1 for the HHR char oxidation. The differences between the oxidative reactivities of the LHR and HHR chars are further discussed in terms of the chemical and physical char properties.
Original languageEnglish
Pages (from-to)2084-2090
JournalEnergy and Fuels
Volume22
Issue number3
DOIs
Publication statusPublished - 1 May 2008
Externally publishedYes

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