Ultra-high oxygen permeable BaBiCoNb hollow fiber membranes and their stability under pure CH4 atmosphere

Consistent interpretation of isotope and chemical oxygen exchange relaxation kinetics in SrFe0.85Mo0.15O3-δ ferrite

This paper is devoted to the study of phase composition and kinetic and thermodynamic characteristics of Mo-doped strontium ferrite SrFe0.85Mo0.15O3-δ (SFM15) under oxygen-conducting membrane working conditions. Single-phase SFM15 with a cubic Pm3̄m structure was synthesized using a ceramic method. It was shown that the molybdenum introduction stabilizes the perovskite cubic structure over a wide range of oxygen pressures and temperatures, preventing the bulk phase transition at high temperatures. Oxygen exchange constants, diffusion coefficients and activation energy of oxygen exchange were obtained using oxygen relaxation and isotopic exchange techniques, and the obtained values are consistent with known literature data. It was shown that the surface reaction rates obtained using chemical and tracer relaxation methods are quantitatively comparable with each other, despite significantly different experimental conditions. This result not only confirms the reliability of the data obtained by independent methods, but also allows one to expand the area of physical conditions for studying the kinetics of oxygen transfer where another method has technical or methodological limitations.

A mini-review on recent developments in SAPO-34 zeolite membranes and membrane reactors

Schematic diagram of a SAPO-34 membrane for various gas separation.

Zeolite membrane reactors: from preparation to application in heterogeneous catalytic reactions

Coupling chemical reaction with membrane separation or known as membrane reactor (MR) has been demonstrated by numerous studies and showed that this strategy has successfully addressed the goal of process intensification.

Catalytic mixed conducting ceramic membrane reactors for methane conversion

Schematic of catalytic mixed conducting ceramic membrane reactors for various reactions: (a) O₂ permeable ceramic membrane reactor; (b) H₂ permeable ceramic membrane reactor; (c) CO₂ permeable ceramic membrane reactor.

Highly Efficient NO Decomposition via Dual-Functional Catalytic Perovskite Hollow Fiber Membrane Reactor Coupled with Partial Oxidation of Methane at Medium-Low Temperature

A novel dual-functional catalytic perovskite hollow fiber membrane reactor was fabricated by integrating BaBi_0.05Co_0.8Nb_0.15O_3-δ (BBCN) perovskite hollow fiber membrane with Ni-phyllosilicate hollow sphere catalysts for simultaneous NO decomposition and partial oxidation of methane (POM) reaction. With this novel catalytic membrane reactor, NO could be completely converted to N₂ at a medium-low temperature (675 °C) owing to instantaneous oxygen removal from the NO decomposition reaction system. Coupled POM reaction on the other side of BBCN hollow fiber membrane not only increased the driving force for oxygen permeation but also produced valuable products (syngas). This novel membrane reactor showed high NO removal capacity at comparatively low temperatures (675-700 °C), which is 100-200 °C lower than those of other membrane reactors reported in literature. In addition, even with the presence of a 2-5% oxygen concentration in NO stream, NO could still be completely decomposed to N₂ via this catalytic BBCN membrane reactor. Evidently, the application of this novel catalytic membrane reactor could overcome the inhibition of oxygen present atmosphere for NO decomposition and achieve a remarkably high efficiency for NO removal.

Highly Permeable Benzotriptycene-Based Polymer of Intrinsic Microporosity

A novel polymer of intrinsic microporosity (PIM) was prepared from a diaminobenzotriptycene monomer using a polymerization reaction based on Tröger's base formation. The polymer (PIM-BTrip-TB) demonstrated an apparent Brunauer, Emmet, and Teller (BET) surface area of 870 m² g^-1, good solubility in chloroform, excellent molecular mass, high inherent viscosity and provided robust thin films for gas permeability measurements. The polymer is highly permeable (e.g., PH₂ = 9980; PO₂ = 3290 Barrer) with moderate selectivity (e.g., PH₂/PN₂ = 11.0; PO₂/PN₂ = 3.6) so that its data lie over the 2008 Robeson upper bounds for the H₂/N₂, O₂/N₂, and H₂/CH₄ gas pairs and on the upper bound for CO₂/CH₄. On aging, the polymer demonstrates a drop in permeability, which is typical for ultrapermeable polymers, but with a significant increase in gas selectivities (e.g., PO₂ = 1170 Barrer; PO₂/PN₂ = 5.4).

The effect of microstructure and surface decoration with K2NiF4-type oxide upon the oxygen permeability of perovskite-type La0.7Sr0.3FeO3−δ hollow fiber membranes

Dense La_0.7Sr_0.3FeO_3−δ (LSF) hollow fiber membranes with two kinds of microstructures (LSF-a and LSF-b) were prepared by the phase inversion/sintering method, and the outside surfaces were modified with K₂NiF₄-type oxide in discontinuous method.