Dual-layer BaCe0.8Y0.2O3-δ-Ce0.8Y0.2O2-δ/BaCe0.8Y0.2O3-δ-Ni hollow fiber membranes for H2 separation

Abstract

Ceramic ion-conducting membrane technology is one of the promising options for hydrogen separation to replace the conventional expensive cryogenic distillation methods. In order to achieve high H2 permeation flux, designing multi-phase membranes possessing high mixed protonic and electronic conductivities in asymmetric structure with a thin dense separating layer is an important strategy for future novel membrane development. Multi-phase dual-layer BaCe0.8Y0.2O3-δ (BCY)-Ce0.8Y0.2O2-δ (YDC)/BCY-Ni hollow fiber membrane with excellent hydrogen permeability was developed by a single-step co-extrusion technique in this work. The thickness of the dense layer of the membrane can be controlled by the powder content of BCY-YDC in the spinning suspension. When the content of BCY-YDC was lowered from 65 to 45 wt%, the thickness of the dense layer was decreased from 33.5 to 14.5 μm. The thin dual-phase BCY-YDC dense layer determines the H2 permeation and the porous BCY-Ni support layer provides the mechanical strength and catalytic effect for surface exchange reactions. Compared to the BCY-YDC single-layer membrane, the H2 flux of such dual-layer asymmetric membrane with dense layer of 17.0 μm was improved significantly by a factor of 2 reaching 0.566 mL cm−2 min−1 at 900 °C under the hydrogen partial pressure difference of 50 kPa. A long term permeation test for 240 h confirmed the high operational stability of the prepared dual layered hollow fiber membrane. The good membrane performance is directly sourced from the excellent integration of the dual layers prepared in one step and thin thickness of the densified separating layer with catalytic porous support.