A novel dual phase membrane 40 wt% Nd_0.6Sr_0.4CoO_3-:δ-60 wt% Ce_0.9Nd_0.1O_2-δ: esign, synthesis and properties

Oxygen permeation, stability and chemical bonding characteristics of 40 wt% Nd_0.6Sr_0.4CoO_3-δ-60 wt% Ce_0.9Nd_0.1O_2-δ (40NSCO-60CNO) dual-phase composite membrane reactors were investigated. The 40NSCO-60CNO oxygen permeable membrane was prepared via an in situ one-pot one-step EDTA-citric acid method. The crystal structure of the 40NSCO-60CNO dual phase material was characterized by X-ray diffraction (XRD) and in situ XRD. The microstructure was investigated using transmission electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM) combined with energy-dispersive X-ray spectroscopy (EDXS) and electron energy-loss spectroscopy (EELS). The results show that the 40NSCO-60CNO composite represents a micro-scale mixture of only the two pure phases NSCO and CNO. The oxygen permeation fluxes through the 40NSCO-60CNO dual phase membrane were measured at elevated temperatures (900-1000 °C) with one side of it exposed to synthetic air and the other side to a flowing He gas stream. A stable oxygen permeation rate of 0.90 mL cm^-2 min^-1 was obtained with a 0.4 mm thick membrane under an air/He oxygen partial pressure gradient at 1000 °C. The 40NSCO-60CNO dual phase membrane with a thickness of 0.6 mm showed a stable oxygen flux of 0.55 mL cm^-2 min^-1 at 950 °C for 100 h under pure CO₂ sweeping.