Influence of Oxygen Carrier on the Autothermicity of a Chemical-Looping Reforming Process for Hydrogen Production

LÓPEZ VAN DER HORST, JULIANA; VOLPE GIANGIORDANO, MARIA FLORENCIA; SUAREZ, FELIPE; PEREZ, FEDERICO M.; GATTI, MARTÍN N.; SANTORI, GERARDO F.; POMPEO, FRANCISCO

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MDPI

Año: 2025 vol. 6

The chemical-looping reforming (CLR) of methane for hydrogen productionemploys a solid oxygen carrier (OC) and combines endothermic and exothermic stages,allowing for potential autothermal operation. This study conducted a thermodynamicanalysis using Gibbs free energy minimization and energy balances to assess the behaviorof WO3, MnWO4, and NiWO4 as OCs in the CLR process. The effects of CH4:OC ratiosand reactor temperatures on equilibrium composition and the energy performance wereexamined. The results demonstrated that elevated reduction temperatures promote OCconversion and the formation of more reduced solid products. Molar ratios above stoichiometricprevent carbon formation, whereas stoichiometric ratios result in higher H2yield, achieving 98% at 1000 ◦C. However, these conditions do not support autothermaloperation, which requires CH4:OC molar ratios above stoichiometric. Additionally, loweroxidation temperatures are preferred regardless of the OC, due to the lower heat needed topreheat the air, which has a greater effect on the net heat. For the reduction temperature,its effect depends on the type of OC analyzed. The maximum H2 yield obtained underautothermal operation was 88% for the three OCs, at 875 ◦C for MnWO4 and 775 ◦C forboth WO3 and NiWO4.