Performance and stability of (ZrO 2 ) 0.89 (Y 2 O 3 ) 0.01 (Sc 2 O 3 ) 0.10 -LaCr 0.85 Cu 0.10 Ni 0.05 O 3-δ oxygen transport membranes under conditions relevant for oxy-fuel combustion

Abstract

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Exploring the Processing of Tubular Chromite- and Zirconia-Based Oxygen Transport Membranes

“…LaCrO 3 is difficult to sinter due to the high volatility of Cr, but it possesses excellent stability over a wide pO 2 range (0.21-10 −22 atm) and can, upon acceptor doping, reach high electronic conductivity [12]. The composition LaCr 0.85 Cu 0.10 Ni 0.05 O 3−δ (LCCN) was recently shown to reach 11.4 S cm −1 at 800 • C and have excellent stability in a wide pO 2 range [13]. A composite membrane of 30 vol % LCCN and 70 vol % 10Sc1YSZ reached an oxygen flux of 1.02 mL cm −2 min −1 at 950 • C in N 2 /air in the shape of a planar thick film [13].…”

“…The composition LaCr 0.85 Cu 0.10 Ni 0.05 O 3−δ (LCCN) was recently shown to reach 11.4 S cm −1 at 800 • C and have excellent stability in a wide pO 2 range [13]. A composite membrane of 30 vol % LCCN and 70 vol % 10Sc1YSZ reached an oxygen flux of 1.02 mL cm −2 min −1 at 950 • C in N 2 /air in the shape of a planar thick film [13].…”

“…Target values are gas permeability of ≥10 −14 m 2 and a strength of ≥50 MPa, based on considerations from references [17,18], respectively. ZrO 2 with 3 mol % Y 2 O 3 (3YSZ) has superior strength and toughness compared to practically all other oxide ceramics while being chemically stable, and it is therefore a commonly used porous support in solid oxide fuel cells and OTM [13,19].…”

“…Pilot-scale stand-alone units for oxygen production using tubular BSCF under compressed air/vacuum have already been made [16,20,21], and there are a few reports on the lab-scale fabrication and testing of other tubular OTM systems [22][23][24]; as it stands, tubular membranes with thermochemical stability allowing direct integration have not yet been made. Techniques to make flat and defect-free planar OTMs, such as stress relief through bending (camber), top loads for controlling this camber, two-step sintering, and enclosed crucibles or sacrificial powder beds [13,25], are not easily transferrable to large-scale processing of tubular systems.…”

“…This membrane composition has demonstrated decent oxygen fluxes in a planar configuration [13], and the support composition has been proven suitable for high gas-permeability [26,27], but it has not yet been established whether sufficient mechanical and chemical integrity can be obtained after the more challenging co-sintering of a tubular system. Indeed, our work shows that while we can make strong and permeable 3YSZ support tubes , the high temperature required for co-sintering of LCCN/10Sc1YSZ on 3YSZ followed by evaporation of chromium makes LCCN unsuitable for large-scale fabrication of tubular OTMs.…”