A novel dual-layer ceramic hollow fibre membrane reactor for methane conversion

A highly compact multifunctional ceramic hollow fibre membrane reactor with a unique dual-layer structure (DL-HFMR) has been developed in this study for methane conversion using a single-step co-extrusion and co-sintering technique. The developed DL-HFMR consists of a thin outer oxygen separation layer (approximately 75 μm) supported on an inner Ni-based catalytic substrate (171 μm). The former is comprised of 40 vol.% La_0.8Sr_0.2MnO_3-δ (LSM) and 60 vol.% yttria-stabilized zirconia (YSZ), while the latter consists of 30 vol.% NiO and 70 vol.% YSZ. The inner support layer possesses a highly porous structure and is catalytic active, after an easy post-reduction of NiO to Ni, to the reactions for methane conversions, such as partial oxidation of methane (POM) to syngas. Benefiting from this membrane reactor design as well as the single-step fabrication technique, a surface area/volume ratio of approximately 2770 m²/m³ can be achieved with a great adhesion between the separation and catalytic support layers. CO selectivity over 90% with a H₂/CO ratio of about 2 can be obtained at 950 °C. Although methane conversion is greatly affected by coke formation during the reaction, the catalytic activity of the inner layer is easily recovered by periodically switching between methane and the sweep gas at high temperatures, because the coke formed during the reaction can be removed by the permeated oxygen.