Mechanisms and Kinetics of Methane Thermal Conversion in a Syngas

• Published in: Industrial & engineering chemistry research 2009-07, Vol.48 (14), p.6564-6572
• Main Authors: Dufour, Anthony, Valin, Sylvie, Castelli, Pierre, Thiery, Sébastien, Boissonnet, Guillaume, Zoulalian, André, Glaude, Pierre-Alexandre
• Format: Article
• Language: English
• Subjects: Applied sciences; Chemical and Process Engineering; Chemical engineering; Chemical Physics; Engineering Sciences; Exact sciences and technology; Kinetics, Catalysis, and Reaction Engineering; Physics
• ISSN: 0888-5885; 1520-5045
• DOI: 10.1021/ie900343b

In order to optimize H2 and CO production from biomass gasification, the thermal decomposition of methane in a reconstituted syngas was investigated in a tubular reactor at 130 kPa, for a gas residence time of 2 s and as a function of temperature (1000−1400 °C), CH4 (7, 14%), H2 (16, 32%), and H2O (15, 25, 30%) initial mole fractions. H2 showed an inhibiting effect on CH4 conversion whereas H2O had few effects. Three detailed elementary mechanisms were used to predict the methane conversion rate and to identify the key reaction pathways. Flow rate analyses showed that carbon oxidation occurs mainly by addition of OH radicals on C2 compounds. OH radicals are mainly produced by CO2 (CO2 + H = CO + OH). The inhibiting role of H2 on CH4 conversion is explained by a competition between the OH radicals consumption channels (H2 + OH = H2O + H). The competition between thermal conversion of methane and reforming of unsaturated C2 explains the soot formation.