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A triple-layer composite membrane with porous-dense-porous structure was proposed to develop a high performance membrane reactor. The triple-layer composite membrane consists of a porous Sr 0.7 Ba 0.3 Fe 0.9 Mo 0.1 O 3− δ (SBFM) layer, a dense 0.5 wt% Nb 2 O 5 -doped SrCo 0.8 Fe 0.2 O 3− δ (SCFNb) layer and a porous La 0.8 Sr 0.2 MnO 3− δ –yttria stabilized zirconia (LSM/YSZ) layer. The porous layers can effectively reduce the corrosion of the reactive atmosphere to the membrane, while the dense layer permeated oxygen effectively. Compared with single layer dense SCFNb membrane reactor, the triple-layer composite membrane reactor can be operated for more than 500 h. At the temperature of 900 °C, the CO 2 conversion can reach 20.58% with the CH 4 conversion, CO selectivity and O 2 flux being about 84%, 97% and 2.13 mL (STP) cm −2 min −1 , respectively. The porous-dense-porous structure can successfully combine the high oxygen permeation and stability of the membrane reactor. [ABSTRACT FROM AUTHOR]

Abstract: A new kind of La0.85Ce0.1Ga0.3Fe0.65Al0.05O3−δ (LCGFA) mixed conducting oxide was prepared by solid-state reaction method. The crystal structure, chemical stability, thermal expansion behavior, mechanical strength and oxygen permeability of this oxide were investigated. LCGFA powder was multiphase and mainly composed of perovskite phase and CeO2 phase. After annealing in 20vol.% CO2 +He for 100h or in 5vol.% H2 +He for 25h at 900°C, LCGFA powders still maintained full perovskite structure. LCGFA oxide showed very low chemical expansion and the average thermal expansion coefficients were 10.29(8), 10.68(8) and 10.73(6)×10−6 °C−1 in the temperature ranges of 200–1000°C in air, nitrogen and carbon dioxide atmospheres, respectively. The three-point bending strength of the LCGFA sample reached 110±5MPa. At 950°C, the oxygen flux of the supported LCGFA membrane with 200μm membrane layer was 6.54(5)×10−7 molcm−2 s−1. The degradation of the membrane performances on either temperature cycling or during prolonged isothermal tests was found almost negligible. [Copyright &y& Elsevier]

Membrane reactors offer a promising approach to converting CO 2 into chemicals, fuels, and value-added products. However, challenges remain in its high energy input and deactivation of the catalyst. Here, we report a breakthrough strategy that uses dielectric barrier discharge (DBD) plasma to enhance the CO 2 splitting in a perovskite-based La 0.6 Sr 0.4 Co 0.5 Fe 0.5 O 3-δ (LSCF) membrane reactor where a traditional catalyst is not required however instead relies on the highly reactive species generated by the CO 2 plasma. The CO 2 conversion, physical and chemical evolution of membranes at different temperatures, CO 2 plasma power, and purging gas were systematically investigated. The maximum CO 2 conversion was achieved at 800 °C and 25 W while reaching 10.6%, 20.0%, and 28.0% via helium, complete oxidation of methane, and partial oxidation of methane purging on the permeate side, respectively. The experimental results obtained under low plasma power consumption suggest that the plasma-assisted membrane reactor strategy has the potential to be energy-efficient and sustainable, particularly when combined with renewable energy sources. [Display omitted] • A plasma-membrane system has been developed for effective CO 2 splitting. • Reactive species from CO 2 plasma improve the membrane surface reactions. • Optimal 28% CO 2 conversion was achieved at 800 °C and 25W plasma power. [ABSTRACT FROM AUTHOR]

CO 2 -tolerant membranes are crucial for oxyfuel combustion systems utilizing oxygen permeable membranes. A newly constructed dual-layer 7-channel hollow fiber membrane consisting of SrFe 0.8 Nb 0.2 O 3-δ (SFN) porous outer layer and SrCo 0.9 Nb 0.1 O 3-δ (SCN) hollow fiber inner layer has been successfully fabricated by co-spinning and one-step thermal process (OSTP) approach in this work. The outer layer can have different porous structures depending on the graphite content of the spinning solution. In the OSTP approach, the in-situ reactive sintering of the membrane materials results in the two layers being well adhered and mechanically robust. At 900 °C under 80% CO 2 -containing in sweeping gas, the oxygen flux of SFN/SCN dual-layer hollow fiber membrane with the porous layer of 91.8 μm was 1.98 mL min−1 cm−2, about 7.1 times as much as the SCN hollow fiber membrane (0.28 mL min−1 cm−2) in the same situations. The porous SFN outer layer was demonstrated to prevent membrane performance degradation effectively. Furthermore, the SFN/SCN dual-layer membrane operated in a 20% CO 2 -containing atmosphere for at least 200 h, maintaining an oxygen flux of 3.20 mL min−1 cm−2 without degradation. As a result of these findings, the SFN/SCN dual-layer 7-channel hollow fiber membrane has significant application potential in CO 2 capture for oxyfuel combustion. [Display omitted] •A dual-layer 7-channel hollow fiber membrane was prepared by one step process. •The membranes exhibit excellent oxygen permeation performance under CO 2 exposure. •Both layers are made of different materials and serve different purposes. •The porous layer provides corrosion protection and enhances mechanical strength. [ABSTRACT FROM AUTHOR]

Polydimethylsiloxane (PDMS), as a representative membrane material with superior permeability, attracts great attention in gas separation, pervaporation and nanofiltration. However, the fabrication of defect-free ultrathin PDMS membrane remains great challenge mainly due to the difficulty in controlling the processability and substrate pore penetration of casting solution. In this work, for the first time, we employed PDMS monomer terminated with acryloyloxy groups (AC-PDMS) to implement fabrication of thin-film composite (TFC) membrane. The ultraviolet (UV) reactivity between acryloyloxy groups induced fast curing of AC-PDMS casting solution, thereby realizing formation of ultrathin selective layer (∼260 nm) and inhibition of substrate pore penetration. By optimizing the UV wavelength, irradiation time and polymer concentration, the resulting AC-PDMS TFC membrane achieved attractive CO 2 permeance of 9635 GPU, with CO 2 /N 2 selectivity of 11.5. Furthermore, chain crosslinking and packing behavior, fabrication of TFC membrane and transport property of AC-PDMS were compared with conventional hydroxyl-terminated PDMS (OH-PDMS). Together with the potential in scalable fabrication, the strategy based on UV crosslinking acryloyloxy-terminated monomers provides a new avenue to produce ultrathin PDMS membranes toward practical application in molecular separation. [Display omitted] • PDMS TFC membrane was fabricated by UV crosslinking acryloyloxy-terminated monomers. • UV crosslinked monomers inhibited pore penetration of PDMS casting solution. • PDMS TFC membrane exhibited outstanding separation performance of CO 2 /N 2. [ABSTRACT FROM AUTHOR]

Molten salt-ceramic dual-phase membranes have great prospects in the selective separation of nitrogen oxides. A gas-tight KNO 3 –Ba 0.5 Sr 0·5 Co 0·8 Fe 0·2 O 3-δ (KNO 3 -BSCF) four-channel hollow fiber membrane was developed in this study. A wide operating temperature window of 350–500 °C with high nitrogen oxides permeance was achieved. The maximum nitrogen oxides permeance reached 9.2 × 10−9 mol m−2 s−1 Pa−1 under the condition of 1% NO 2 , 1% CO 2 and 20% O 2 at 500 °C. The presence of nitrogen oxides was able to suppress the reaction of BSCF oxide with CO 2 to form carbonates. Insights on the transport mechanism of nitrogen oxides transport were provided and the existence of nitrite route for nitrogen oxides transport was firstly demonstrated by experiments. An 1800 h long-term nitrogen oxides permeation was running on the KNO 3 -BSCF hollow fiber membrane while the permeance increased by a factor of ~40 (5.2 × 10−10 mol m−2 s−1 Pa−1 to 2.2 × 10−8 mol m−2 s−1 Pa−1 at 450 °C) due to the partial decomposition of nitrate into nitrite. This nitrite route was also verified in KNO 3 /KNO 2 -BSCF hollow fiber membrane constructed by preloading 30 wt% nitrite in molten salt. [Display omitted] • Molten nitrate dual-phase four-channel hollow fiber membrane was constructed for high efficient NO x separation. • Molten salts were mainly constrained in the finger-like layers and an 1800 h long-term stability evaluation was achieved. • The existence of nitrite route for nitrogen oxides transport in the dual-phase membrane was firstly proved by experiments. [ABSTRACT FROM AUTHOR]

Fabricating dual-phase hollow-fiber membranes via a one-step thermal processing (OSTP) approach is challenging, because of complex sintering kinetics and the subsequent impacts on membrane morphology, phase stability, and permeation properties. In this study, we have demonstrated that Ce 0.8 Sm 0.2 O 2-δ -SrCo 0.9 Nb 0.1 O 3-δ (SDC-SCN) four-channel hollow fiber membrane can be manufactured via a single high-temperature sintering process, by using metal oxides and carbonates directly as membrane materials (sources of metal ions). It has been found that use of a low ramping rate reduces grain sizes, increases grain and forming cobalt oxide nanoparticles, a key step to promoting surface exchange process followed by enhancing oxygen permeation. While the grain boundary interface region can be limited to approximately 20–30 nm. At 1173 K oxygen permeation of the SDC-SCN four-channel hollow fiber membrane was measured at approximately 1.2 mL cm−2·min−1 using helium as the sweep gas. Meanwhile, the dual-phase membrane shows a good tolerance to carbon dioxide, with the oxygen permeation flux fully recovered after long-term exposure to carbon dioxide (more than 100 h). This will enable further application of the OSTP approach for preparing dual-phase multi-channel hollow fiber membranes for applications of oxyfuel combustion, catalytic membrane reactors and carbon dioxide capture. Image 1 • Dual-phase hollow fiber fabricated via the one-step thermal processing (OSTP) is proposed. • Ramping rate is demonstrated to be closely linked to the membrane performance. • Ion exchange at the two-phase grain boundaries can be limited to the nanometer-scale. • The dual-phase hollow fiber fabricated via the OSTP shows an excellent CO 2 tolerance. [ABSTRACT FROM AUTHOR]