Combined steam and carbon dioxide reforming of methane and side reactions: Thermodynamic equilibrium analysis and experimental application

•Selected variables have a significant influence on yields of synthesis gas.•(CO2+H2O)/CH4 affects the temperature which can achieve the maximum conversion.•Coke is formed at low temperatures even with excess oxidizing agent.•The occurrence of RWGS becomes critical in real chemical reactions.•Equili...

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Veröffentlicht in:Applied energy 2016-07, Vol.173, p.80-91
Hauptverfasser: Jang, Won-Jun, Jeong, Dae-Woon, Shim, Jae-Oh, Kim, Hak-Min, Roh, Hyun-Seog, Son, In Hyuk, Lee, Seung Jae
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Sprache:eng
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Zusammenfassung:•Selected variables have a significant influence on yields of synthesis gas.•(CO2+H2O)/CH4 affects the temperature which can achieve the maximum conversion.•Coke is formed at low temperatures even with excess oxidizing agent.•The occurrence of RWGS becomes critical in real chemical reactions.•Equilibrium conversions are maintained for 500h without detectable deactivation. Thermodynamic equilibrium analysis of the combined steam and carbon dioxide reforming of methane (CSCRM) and side reactions was performed using total Gibbs free energy minimization. The effects of (CO2+H2O)/CH4 ratio (0.9–2.9), CO2:H2O ratio (3:1–1:3), and temperature (500–1000°C) on the equilibrium conversions, yields, coke yield, and H2/CO ratio were investigated. A (CO2+H2O)/CH4 ratio greater than 1.2, a CO2:H2O ratio of 1:2.1, and a temperature of at least 850°C are preferable reaction conditions for the synthesis gas preparation in the gas to liquid process. Simulated conditions were applied to the CSCRM reaction and the experimental data were compared with the thermodynamic equilibrium results. The thermodynamic equilibrium results were mostly consistent with the experimental data, but the reverse water gas shift reaction rapidly occurred in the real chemical reaction and under excess oxidizing agent conditions. In addition, a long-term stability test (under simulated conditions) showed that the equilibrium conversion was maintained for 500h and that the coke formation on the used catalyst was not observed.
ISSN:0306-2619
1872-9118
DOI:10.1016/j.apenergy.2016.04.006