The role of ionic-electronic ratio in dual-phase catalytic layers for oxygen transport permeation membranes

• DOI: 10.1016/j.memsci.2023.121578
• Publication Date: 2023-03-10T20:47:36Z
• Authors: Marwan Laqdiem; Julio Garcia-Fayos; Laura Almar; Maria Balaguer; Jose M. Serra
• Keywords: Concentration polarization; Oxygen transport; Limiting current

Peer reviewed<br/>Financial support by the Spanish Ministry of Science and Innovation (RTI2018-102161 and CEX2021-001230-S grants funded by MCIN/AEI/10.13039/501100011033), and the Universitat Politècnica de València (UPV) is gratefully acknowledged. The authors would like to thank Dr. J. L. Jordà for the help with XRD. Also, we acknowledge the support of the Servicio de Microscopía Electrónica of the UPV. We thank M. Fabuel for helping with the material and sample elaboration<br/>Oxygen transport membrane (OTM) is an appealing technology for contributing to the decarbonization of the industry via oxy-combustion processes. Dual-phase composite materials are promising membrane candidates for this kind of processes due to their stability under CO atmospheres. Even so, the oxygen permeation through this kind of membranes is still limiting for practical application. A key well-studied membrane performance parameter is the ratio between composite crystalline phases since the percolative channels for each phase determine the final oxygen permeation flux. Here, we investigate the influence of the phase ratio on the surface-exchange reactions in catalytically-activated composite membranes composed of NiFeO (NFO) and CeTbO (CTO). Electrical impedance spectroscopy (EIS) and oxygen permeation studies revealed a decrease in polarization resistance and an increase in oxygen flux as the ionic-phase proportion in the catalytic layers increases. At 850 °C, the 20NFO80CTO catalytic layer on a 650 μm-thick 50NFO50CTO membrane reaches an oxygen flux of 0.2 mL min·cm. That permeation was improved by a factor of 2.5 regarding the opposite phase ratio (80NFO20CTO) and 1.3 regarding a balanced phase ratio (50NFO50CTO) in the catalytic layer. The 20NFO80CTO electrodes showed the lowest resistances compared to the electrodes with higher NFO content, confirming that the O surface exchange is controlled by ionic-phase mechanisms rather than electronic phase ones.<br/>