Oxygen conducting perovskite capillary membranes

Challenge: Separation of oxygen from air

The separation of oxygen from air is of economic and environmental importance for many large-scale processes. In recent years, mixed-conducting perovskites have increasingly come into focus as membrane materials for the selective separation of oxygen from gas mixtures.

New perovskite membrane combines excellent material properties with effective specific membrane surface area

In order to combine the special material properties of perovskites with an effective specific membrane surface, we have developed oxygen conducting perovskite capillary membranes at Fraunhofer IGB. Compared to conventional geometries (disks, tubes, multi-channel elements), these membranes have the highest packing density (separation area per volume) and extremely low material consumption.

A wet-spinning process followed by sintering enables perovskite capillaries with outer diameters of 750 µm to 3 mm and wall thicknesses of 80 to 300 µm to be produced on a pilot scale. For example, gas-tight capillaries made of the perovskite material BaCoxFeyZrzO3-δ show oxygen permeation of up to 10 ml min-1 cm-2 and excellent selectivity (separation factor O2/N2 > 10,000) at temperatures of 950°C [1].

Successful application tests

Together with partners from research and industry, Fraunhofer IGB has tested these membranes for various applications [2, 3]. The capillaries can be used, for example, to produce oxygen-enriched air or even extremely pure oxygen and for the partial oxidation of methane (POM). The splitting of water coupled with the POM using these membranes facilitates the simultaneous production of pure hydrogen and syngas.


Typical geometry of a perovskite hollow fiber membrane
© Fraunhofer IGB
Typical geometry of a perovskite hollow fiber membrane. Outer diameter: 900 μm, inner diameter: 600 μm, length: 30 cm.
12 fiber floating head module
© Fraunhofer IGB
12 fiber floating head module
Recovery of oxygen-enriched air using perovskite hollow fiber membranes.
© Fraunhofer IGB
Recovery of oxygen-enriched air using perovskite hollow fiber membranes

Applications

  • Generation of oxygen enriched air
  • Generation of extremely pure oxygen
  • Partial oxidation of methane (POM)
  • Simultaneous production of pure hydrogen and synthesis gas during electrolytic water splitting when coupled with POM

Publications

  1. Schiestel, T., Kilgus, M., Peter, S., Caspary, K. J., Wang, H., & Caro, J. (2005). Hollow fibre perovskite membranes for oxygen separation. Journal of Membrane Science, 258(1), 1-4. doi:https://doi.org/10.1016/j.memsci.2005.03.035.
  2. Jiang, H., Cao, Z., Schirrmeister, S., Schiestel, T., & Caro, J. (2010). A Coupling Strategy to Produce Hydrogen and Ethylene in a Membrane Reactor. Angewandte Chemie International Edition, 49(33), 5656-5660. doi:https://doi.org/10.1002/anie.201000664.
  3. Jiang, H., Wang, H., Liang, F., Werth, S., Schiestel, T., & Caro, J. (2009). Direct Decomposition of Nitrous Oxide to Nitrogen by In Situ Oxygen Removal with a Perovskite Membrane. Angewandte Chemie International Edition, 48(16), 2983-2986. doi:https://doi.org/10.1002/anie.200804582.

Reference projects

PiCK – Plasma-induced CO2 conversion

The Kopernikus satellite project PiCK is developing a novel process employing implementing regenerative electrical energy to utilize climate-damaging CO₂ as a carbon source. A combination of plasma and membrane processes  will be used to break down CO₂ into O₂ and CO₂ which serves as the starting product for the synthesis of platform chemicals and chemical energy stores such as methanol. Within the framework of the project, gas-tight ceramic capillaries were produced at IGB for the first time. These capillaries are both CO₂-stable and suitable for the separation of oxygen from a plasma.

Project duration: February 2017 – February 2020