Thermodynamic analysis of Ceria for partial oxidation of methane and syngas production

Abstract:Chemical looping syngas production is a two-step redox cycle, with oxygen carriers (metal oxides) circulating between two interconnected reactors. In this paper, the performance of pure CeO2/Ce2O3 redox pair was... [ view full abstract ]

Abstract:

Chemical looping syngas production is a two-step redox cycle, with oxygen carriers (metal oxides) circulating between two interconnected reactors. In this paper, the performance of pure CeO₂/Ce₂O₃ redox pair was investigated for syngas production via methane reduction. A comprehensive thermodynamic analysis for methane reduction and water and CO₂ splitting was performed through Gibbs free energy minimization in ASPEN Plus. The reduction reactor was studied by varying the CH₄/CeO₂ molar ratio between 0.4 and 4 along with the temperature from 500 to 1000^oC. In the oxidation reactor, steam and carbon dioxide mixture oxidized the reduced metal back to CeO₂, while producing simultaneous streams of CO and H₂ respectively. Within the oxidation reactor, the flow and composition of the mixture gas was varied, together with reactor temperature between 500 to 1000^oC. The results indicate that the optimal reduction condition is achieved between 900 to 950^oC with CH₄/CeO₂ ratio of 0.7-0.8, while, for the oxidation reactor, it can vary between 600 to 900 ^oC based on the requirement of the final product output (H₂/CO). The system efficiency was around 62% corresponding to an isothermal system at 900^oC, and complete redox reaction of the metal oxide.

Keywords: Oxygen Carriers, Chemical looping, Syngas, Thermodynamic Analysis