Partial oxidation of methane in hollow‐fiber membrane reactors based on alkaline‐earth metal‐free CO2‐tolerant oxide

The U‐shaped alkaline‐earth metal‐free CO 2 ‐stable oxide hollow‐fiber membranes based on (Pr 0.9 La 0.1 ) 2 (Ni 0.74 Cu 0.21 Ga 0.05 )O 4+δ (PLNCG) are prepared by a phase‐inversion spinning process and applied successfully in the partial oxidation of methane (POM) to syngas. The effects of temperature, CH 4 concentration and flow rate of the feed air on CH 4 conversion, CO selectivity, H 2 /CO ratio, and oxygen permeation flux through the PLNCG hollow‐fiber membrane are investigated in detail. The oxygen permeation flux arrives at approximately 10.5 mL/min cm 2 and the CO selectivity is higher than 99.5% with a CH 4 conversion of 97.0% and a H 2 /CO ratio of 1.8 during 140 h steady operation. The spent hollow‐fiber membrane still maintains a dense microstructure and the Ruddlesden‐Popper K 2 NiF 4 ‐type structure, which indicates that the U‐shaped alkaline‐earth metal‐free CO 2 ‐tolerant PLNCG hollow‐fiber membrane reactor can be steadily operated for POM to syngas with good performance. © 2014 American Institute of Chemical Engineers AIChE J , 60: 3587–3595, 2014