High CO₂ permeation using a new Ce_0.85Gd_0.15O_2-δ-LaNiO₃ composite ceramic-carbonate dual-phase membrane

This work shows the synthesis, characterization and evaluation of dense-ceramic membranes made of Ce_0.85Gd_0.15O_2-δ-LaNiO₃ (CG-LN) composites, where the fluorite-perovskite ratio (CG:LN) was varied as follows: 75:25, 80:20 and 85:15 wt.%. Supports were initially characterized by XRD, SEM and electrical conductivity (using vacuum and oxygen atmospheres), to determine the composition, microstructural and ionic-electronic conductivity properties. Later, supports were infiltrated with an eutectic carbonates mixture, producing the corresponding dense dual-phase membranes, in which CO₂ permeation tests were conducted. Here, CO₂ permeation experiments were performed from 900 to 700°C, in the presence and absence of oxygen (flowed in the sweep membrane side). Results showed that these composites possess high CO₂ permeation properties, where the O₂ addition significantly improves the ionic conduction on the sweep membrane side. Specifically, the GC80-LN20 composition presented the best results due to the following physicochemical characteristics: high electronic and ionic conductivity, appropriate porosity, interconnected porous channels, as well as thermal and chemical stabilities between the composite support and carbonate phases.