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

Abstract

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 41d (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.

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

“…Shao et al [139] reached a stable and relatively high oxygen flux of 8.6 × 10 −6 mol cm −2 s −1 using a BSCF planar membrane. Contrary to many other studies [219] that reported that the BSCF material interacts with the CO 2 , the authors could keep a long-term (500 h) experiment without any noticeable change in the POM performance.…”

Perovskite materials in energy storage and conversion

“…During the past two decades, mixed oxygen ion‐ and electronic‐conducting membranes have received considerable attention as novel ways to separate oxygen from air at substantially reduced energy consumption . The permeation of oxygen through a mixed conducting membrane is based on the simultaneous diffusion of oxygen ions and electrons through the membrane bulk using the drive force of an oxygen potential difference across the two surfaces of the membrane .…”

Oxygen transport kinetics of MIEC membranes coated with different catalysts

“…Mixed ionic‐electronic conducting (MIEC) oxides are a kind of multi‐functional materials. It can be applied as high active cathodes for solid oxide fuel cells (SOFCs), as membranes for oxygen separation with infinite selectivity, as catalytic membrane reactors for selective oxidation or reduction reactions, integrated with oxy‐fuel process for CO 2 capture . Among these applications, MIEC materials as oxygen separation membranes producing high purity oxygen at elevated temperature is promising to be commercialized in the near future due to its low costs and high efficiency compared with pressure swing adsorption and cryogenic distillation technologies .…”