Effects of Nb and Sn co-doping on the structure and properties of SrCoO_3-δ oxygen transport membranes

Abstract

The structure and oxygen permeability of SrCo 0.9-x Nb 0.1 Sn x O 3-δ (x = 0, 0.03, and 0.05) perovskite membranes were systematically investigated by co-doping the B-site of SrCoO 3-δ oxide with Nb and Sn. Combined X-ray and neutron diffraction experiments showed that all materials crystallized in the tetragonal P4/mmm space group and that the crystal structures approached the ideal cubic perovskite structure with increasing Sn concentration. In addition, X-ray photoelectron spectra confirmed that Sn-doping increases the (Co, Nb, Sn)-O bond strengths. The impact of Sn-doping on the oxygen transport of dense SrCo 0.9-x Nb 0.1 Sn x O 3-δ membranes was also investigated, under air/He gradient, as a function of both temperature and membrane thickness. The results showed that the oxygen transport of SrCo 0.9 Nb 0.1 O 3-δ is governed by oxygen ion diffusion, while the oxygen surface exchange reaction is the limiting process for the Sn-doped membranes, SrCo 0.

Toward High Performance Mixed Ionic and Electronic Conducting Perovskite-Based Oxygen Permeable Membranes: An Overview of Strategies and Rationales

“…150 In addition, the large TEC induces a thermal mismatch between materials. 136,151 Therefore, the OPM with excellent oxygen permeability and CO 2 resistance has attracted the wide attention of researchers. 8 A two-phase membrane is a potential membrane with good oxygen permeability and high chemical stability.…”

“…Although BSCF and LSCF have outstanding oxygen permeabilities, their low mechanical strength and poor chemical structural stability largely limit their long-term operation in CO 2 and low oxygen partial pressure atmospheres. − Taking BSCF as an example, when He is used as the sweep gas, the membrane showed high oxygen flux, but when pure CO 2 was used as the sweep gas, a carbonate was generated on the membrane surface; the oxygen permeability cannot be detected due to the protective property of the carbonates . In addition, the large TEC induces a thermal mismatch between materials. , Therefore, the OPM with excellent oxygen permeability and CO 2 resistance has attracted the wide attention of researchers . A two-phase membrane is a potential membrane with good oxygen permeability and high chemical stability.…”