Thermodynamic Study on the Feasibility of a New Combined Chemical Looping Process for Syngas Production

Abstract

Methane Chemical Looping mixed dry reforming – CLMDR (dry reforming and partial oxidation) is an integrate process that utilizes CO₂ directly, in presence of carrier materials, for the production of syngas with tuneable H₂/CO molar ratio. Herein Cerium oxide was selected as reference source of oxygen and its use in the CLMDR process was evaluated by means of thermodynamic tools of Aspen Plus process simulator. Crucial features such as reforming and regeneration operative temperature, oxygen to methane molar ratio and CO₂ addition were investigated in order to identify the most suitable and effective conditions for process. Simulation results of the proposed metal oxide were compared on the basis of methane conversion and syngas purity. Relevantly, cerium-based oxide was found to be selective in syngas production even when CO₂ was added to the reforming reactor.
After the required thermodynamic validation, a fixed bed reactor on lab scale was specifically designed and fabricated, and cerium oxide oxygen carrier characterized by Thermogravimetric analysis.
Thermodynamic results and experimental tests proved the solid/gas chemical reaction takes place with appreciable conversions, and they also demonstrated the stability of the oxygen carrier redox properties during several cycles, thus confirming the feasibility of this new process.