Effects of Lanthanides on the Structure and Oxygen Permeability of Ti-doped Dual-phase Membranes

TL;DR

This study investigates how different lanthanide elements affect the structure and oxygen permeability of Ti-doped dual-phase membranes, aiming to improve stability and performance for CO2 separation.

Contribution

It systematically analyzes the impact of various lanthanides on membrane structure and permeability, introducing new dual-phase materials with enhanced stability in CO2 atmospheres.

Findings

Larger lanthanide atomic number reduces unit cell size and oxygen permeability.

Optimal membrane achieved JO2 of 0.60 and 0.54 mL min-1 cm-2 at 1000°C.

Membranes maintained stability for over 100 hours in CO2 environment.

Abstract

The trade-off effect of the oxygen permeability and stability of oxygen transport membranes (OTMs) still exists in working atmospheres containing CO2. Herein, we reported a new series of 60 wt%Ce0.9Ln0.1O2-{\delta}-40wt%Ln0.6Sr0.4Fe0.9Ti0.1O3-{\delta} (CLnO-LnSFTO, Ln = La, Pr, Nd, Sm, Gd, Tb) dual-phase OTMs by selecting different Ln elements based on the reported highly stable Ti-doped CPrO-PrSFTO. The effects of different Ln elements on the structure and oxygen permeability of Ti-doped dual-phase OTMs were systematically studied. Basically, as the atomic number of Ln elements increases, the unit cell parameters of both the fluorite phase and the perovskite phase become smaller. The unit cell volume and spatial symmetry of the perovskite phase are reduced, resulting in a reduction in oxygen permeability. The optimal CLaO-LaSFTO showed JO2 of 0.60 and 0.54 mL min-1 cm-2 with He and CO2 sweeping at 1000 oC, respectively. In addition, all CLnO-LnSFTO OTMs could work for more than 100 hours with no significant performance degradation in a CO2 atmosphere, maintaining excellent stability. This work explores candidate OTM materials for CO2 capture and oxygen separation, as well as provides some ideas for addressing the trade-off effect.