Fabrication and performance of a tubular ceria based oxygen transport membrane on a low cost MgO support

Abstract

a b s t r a c tA 30 lm thin-film tubular CGO (Ce 0.9 Gd 0.1 O 1.95Àd ) membrane with catalytic layers on both sides has been prepared by dip-coating on a low cost, porous magnesium oxide (MgO) support. The MgO support was fabricated through a thermoplastic extrusion process. Support, thin membrane and catalytic layers were sintered in individual steps at temperatures between 1250 and 1300°C to achieve a controlled removal of binder and organic additives and to obtain the desired, defect free microstructure. The prepared asymmetric tubular CGO membrane has been tested at elevated temperatures (up to 900°C) using atmospheric air and N 2 , H 2 for the feed and sweep side respectively. The oxygen permeation was 4 N ml min À1 cm À2 at 850°C using H 2 on one side and air on the other side.

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

“…Since the temperature required to densify the LCCN/10Sc1YSZ membrane was higher than expected (>1400 °C), and the membrane supports are quite dense and more than strong enough at 1400 °C, higher amounts of pore formers than 61.5 and 64.3 vol % could be considered to retain high gas permeability too after sintering at >>1400 °C. The strength of our 3YSZ tubes ( Table 2) is similar to previously reported planar 3YSZ porous supports (~150 MPa at 45% porosity and ~100 MPa at 55% porosity) [19], twice as strong as porous MgO tubes (82 MPa at 42% porosity) [33], and more than four times as strong as porous BSCF tubes (20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36) MPa at 41% porosity) [6]. The gas permeability of the 3YSZ tubes is at the same time improved by an order of magnitude compared to those of MgO (4.7 × 10 −16 m 2 ) at similar porosity (42%) [33].…”

“…Tubular membranes have advantages compared to planar, such as easier sealing and higher tolerance for thermal gradients [15]. 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.…”

Mixed Ionic-Electronic Conducting Membranes (MIEC) for Their Application in Membrane Reactors: A Review

“…In fact, the oxygen permeation rate in MIEC membranes is controlled by two different mechanisms, such as ionic transport within the membrane and surface membrane exchange. When the permeation process is controlled by bulk diffusion, the oxygen permeate flux will increase when decreasing the thickness of the membrane [25,26]. Membranes with a thickness in the order of 400 to 500 μm is, however, sufficiently small, because the surface exchange rate becomes limiting for smaller membrane thicknesses, as shown in Figure 1 [27].…”

“…An oxygen selective layer supported onto a porous substrate is the simplest example of an asymmetric membrane structure. Additional layers with specific functions can be added, like a surface activation layer and/or a catalytic layer, to improve and extend the performance of the membranes, which also increases the complexity of the membrane structure (see Figure 2) [26,30]. While several articles have been published on self-supported MIEC oxygen transport membranes, only a limited number of articles were published on the production and testing of asymmetric membranes.…”

MgO as a non-pyrolyzable pore former in porous membrane supports

“…Porous ceramic supports are key components in asymmetric, inorganic membranes. 1,2 Oxygen transport membranes for example, only reach sufficiently high performance when used as thin, dense membranes supported on thicker, gas-permeable macroporous supports. 3,4 Their fabrication should be suitable for large volumes, also in non-planar shapes such as tubes.…”