Ceramic-carbonate Dual-phase Membrane Research Articles

CO2-selective membrane reactor process for water-gas-shift reaction with CO2 capture in a coal-based IGCC power plant

Integrated gasification combined cycle (IGCC) power plants enable pre-combustion carbon capture to reduce CO2 emissions. Membrane water-gas-shift (WGS) reactors can intensify these processes by converting raw syngas to H2 with simultaneous CO2 capture in one unit. This paper reports process design and techno-economic analysis (TEA) for a membrane reactor (MR) process with a CO2 selective ceramic-carbonate dual-phase (CCDP) membrane for WGS reaction with CO2 capture for a IGCC power plant. The target performance includes CO conversion > 95 %, hydrogen purity > 90 %, CO2 purity > 95 %, and carbon capture > 90 %. Using a commercial catalyst and a CCDP membrane, the MR can achieve the performance target at 750 °C and space velocity of 250 h−1. The outcome of the process design and TEA shows that the CCDP MR has an operating cost of $24 M/year, significantly lower than that for the conventional processes (40 M$/year). However, the MR process has a higher capital cost ($1007 M) than the conventional process ($527 M) because of the higher cost of the CCDP MRs. Modeling analysis shows a MR with higher CO2 permeance can deliver the target at a higher space velocity and lower membrane surface area to catalyst volume ratio, leading to a significantly reduced MR capital costs.

Modeling analysis of water-gas-shift reaction on catalyst-packed ceramic-carbonate dual-phase membrane reactor for hydrogen production

Water-gas shift (WGS) reaction for hydrogen production and CO2 removal/capture in a catalyst-packed CO2-permselective membrane reactor is studied experimentally and simulated with a computational model. The reactor utilizes a tubular dense ceramic-carbonate dual-phase membrane with a commercial high-temperature WGS catalyst. Equations governing CO2 permeation through the membrane and WGS reaction kinetics on the catalyst were obtained through independent CO2 permeation experiments and a fixed-bed reaction kinetic study. The simulation results using the validated model are presented to examine the effects of feed gas composition, steam/CO ratio, gas hourly space velocity, temperature, reactor pressure, sweep to feed molar flow rate ratio, and the membrane area to catalyst volume ratio on the performance of the membrane reactor for WGS with CO2 removal. Under optimized conditions, the catalyst-packed membrane reactor for WGS demonstrates significantly enhanced CO conversion and product H2 purity by effectively removing/capturing CO2 from the WGS reaction side.

Water-gas shift reaction in ceramic-carbonate dual-phase membrane reactor at high temperatures and pressures

Water-gas-shift (WGS) reaction is a critical step in integrated gasification combined cycles (IGCC) power plants with CO2 capture. Membrane reactors made with a CO2-permselective ceramic-carbonate dual-phase (CCDP) membrane offers the potential to enhance hydrogen yield with simultaneous CO2 capture for WGS reaction. The present work studies operation of WGS reaction in a tubular membrane reactor made of samarium-doped ceria infiltrated with lithium/sodium molten carbonate mixture. The WGS reaction was performed in the membrane reactor with and without a high-temperature WGS catalyst at 800–850 °C, feed pressure of 7 bar, the space velocity of 150–3000 h−1, and a feed gas mixture of 45.7/13.1/41.3 mol% CO/CO2/N2 with steam to carbon ratio of 4. The results show that the catalyst-free membrane reactor can convert 92% of carbon monoxide into CO2 and H2 and recover 29% CO2 at 850 °C and a space velocity of 150 h−1. However, in the catalyst-free membrane reactor, a significant amount of unwanted carbon deposition is observed. The side reactions can be minimized by reducing the operating pressure and increasing the operating temperature and space velocity, and completely avoided using a high-temperature catalyst at space velocity>500 h−1. The membrane reactor with a WGS catalyst achieves CO conversion of about 85%, above the equilibrium conversion, and 40% CO2 recovery without carbon deposition at high temperature and pressure. The membrane remains in the same structure and gas-tightness after the WGS reaction tests.

Tape-casting and freeze-drying gadolinia-doped ceria composite membranes for carbon dioxide permeation

Porous ceria: 20 mol% gadolinia (20GDC) ceramic membranes were prepared by tape casting (TC) and freeze-drying (FD) techniques, obtaining ceramic matrices with randomly dispersed round pores and with an aligned pore structure, respectively. Samples were sintered at 1450 °C, followed by infiltration of molten eutectic sodium-lithium carbonates (NLC). The pore morphology of 20GDC-TC and 20GDC-FD composite membranes was evaluated by analysis of scanning electron microscopy images. The electrical resistivity was determined by electrochemical impedance spectroscopy in the 1 Hz - 10 MHz frequency range from 300 °C to 700 °C, covering the solid-to-molten NLC temperature range, showing that the aligned pore structure improved the conductivity of the ceramic matrix in addition to facilitating molten carbonate infiltration, improving the total (bulk + interfaces) electrical conductivity of the composite membrane. Permeation experiments showed high CO 2 permeation rates reached 5.35 × 10 −7 mol m −2 s −1 Pa −1 at 800 °C. The infiltration of molten sodium-lithium carbonate in gadolinium-doped ceria prepared by the freeze-drying technique is proposed as an optimized procedure for producing membranes for carbon dioxide separation. - Ceramic-carbonate dual-phase membranes were successfully prepared by tape casting and freeze-drying techniques. - Ceramic matrices were produced with aligned porosity for optimizing carbon dioxide permeation. - Electrochemical impedance spectroscopy measurements indicated improved carbonate and oxygen ion conductivity in the membranes with porous matrices obtained by freeze drying. - CO 2 permeance for the membrane produced by freeze-drying reached 5.35 × 10 −7 mol m −2 s −1 Pa −1 at 800 °C

High-pressure CO2 permeation properties and stability of ceramic-carbonate dual-phase membranes

CO 2 permeation properties and stability of ceramic-carbonate dual-phase membranes at high pressures/temperatures are critical to their CO 2 separation and membrane reactor applications, but such data are not available in the literature. This work aims to study the effect of high transmembrane pressure on CO 2 permeation flux and the stability of molten carbonate in the dual-phase samarium-doped ceria (SDC) and molten-carbonate (MC) membranes. Dead-end porous SDC tubular supports were made by a cold isostatic press (CIP)/sintering method with a low porosity (below 7%), and gas-tight SDC-MC membranes were prepared by direct infiltration of molten lithium and sodium carbonate mixture into SDC pores, with a MC volume fraction less than 7%. CO 2 permeation/separation tests were performed on the SDC-MC membranes using feed gas of equal molar CO 2 /N 2 mixture at feed pressures up to 15 atm and sweep gas of helium at 1 atm. CO 2 permeation flux for the SDC-MC membranes depends logarithmically on feed/permeate CO 2 pressure ratio in 660–810 o C. The temperature dependence of CO 2 permeation shows activation energy of 30 kJ/mol. Due to the small MC volume fraction and hence low effective carbonate conductivity, CO 2 permeation of the SDC-MC membranes is dominated by the carbonate ionic conduction in the MC phase. The SDC-MC membranes remain in the same structure, morphology, and gas-tightness after CO 2 separation tests at high feed pressures and temperatures, showing high stability of SDC-MC membranes for high-temperature, high-pressure separation and chemical reaction applications. • Strong ceramic-carbonate dual-phase membranes can be made by the cold isostatic press method. • High-pressure CO 2 permeation flux depends logarithmically on feed/permeate CO 2 partial pressure ratio controlled by carbonate ionic conduction. • Samarium-doped ceria-molten carbonates membranes are stable at high pressures/high temperatures.

High-temperature CO2 perm-selectivity of yttrium-doped SDC ceramic–carbonate dual-phase membranes

New Y-doped SDC ceramic–carbonate dual-phase membranes were prepared, characterized and evaluated, presenting high CO2 perm-selective properties.

Mixed-conducting ceramic-carbonate dual-phase membranes: Gas permeation and counter-permeation

CO2 and O2 permeable ceramic-carbonate dual-phase membranes can be used in membrane reactors for applications such as selective oxidation of hydrocarbons. Two ceramic-carbonate dual-phase membranes consisting of mixed electronic-ionic conducting perovskite-type ceramics of Pr0.6Sr0.4Co0.2Fe0.8 and SrFe0.9Ta0.1O3-δ are studied for CO2 and O2 permeation and counter-permeation. The geometric factors for the carbonate phase and ceramic phase, obtained from the data of helium permeation and electrical conductivity, are used to calculate the effective carbonate and oxygen ionic conductivity in the carbonate and ceramic phase. Without counter-permeation, O2 permeation through the dual-phase membrane is controlled by oxygen ionic conduction in the ceramic phase and CO2 permeation is determined by the total conductance including effective carbonate and oxygen ionic conductivities in both phases. When the dual-phase membrane is exposed to CO2 on one side and O2 on the other side, counter-permeation of CO2 and O2 occurs in the opposite directions across the membrane. With CO2 counter-permeation, the oxygen ionic flux is higher than that without counter-permeation due to an increase in the driving force for oxygen transport. CO2 permeation consumes oxygen ions transporting through the membrane, resulting in a lower O2 permeation flux compared with the O2-only permeation case. However, O2 counter-permeation has negligible effect on CO2 permeation flux for the dual-phase membranes.

Hydrogen production with carbon dioxide capture by dual-phase ceramic-carbonate membrane reactor via steam reforming of methane

The existing process for hydrogen production from methane through steam-reforming requires multiple reactors and separators and is thus costly and energy-intensive. This paper reports a new concept of CO2-permselective membrane reactor for promoting hydrogen production via steam reforming of methane (SRM) with CO2 capture. The membrane reactor is made of a ceramic-carbonate dual-phase membrane with a two-layered asymmetric wall structure. Bismuth-yttrium-samarium oxide (Bi1.5Y0.3Sm0.2O3-δ, BYS) was added to the support layer to make it non-wettable by molten carbonate, leaving the samarium-doped ceria (Sm0.2Ce0.8O2-δ, SDC) layer to form a thin (~150 μm) CO2-permselective SDC/molten-carbonate dual-phase layer after molten carbonate infiltration. The output product composition from the membrane reactor confirms that in situ CO2 removal effectively promotes water-gas shift conversion in SRM and thus enhances hydrogen yield. At 900 °C with feed pressure at 1 atm, the membrane reactor achieves 90% hydrogen yield with 84% CO2 recovery, which poses significant improvement when compared with conventional fixed-bed reactor under similar conditions. Analysis of CO2 permeation activation energy suggests that surface reaction rate might have an effect on CO2 permeation flux for the thin SDC/molten-carbonate membranes. Under atmospheric conditions the CO2 permeation with reactive feed for SRM is lower than with non-reactive feed due to lower driving force under reactive conditions in the feed.

High CO2 permeability of ceramic-carbonate dual-phase hollow fiber membrane at medium-high temperature

CO2 separation through ceramic-carbonate dual-phase membrane from various industrial carbon sources has become a promising way to solve the high-temperature CO2 emission. In this study, we synthesize Ce0.8Sm0.2O2-δ(SDC)-carbonate dual-phase hollow fiber membranes using phase inversion method to separate CO2 under different feed conditions at high temperature. The SDC-carbonate hollow fiber membranes show not only high CO2 permeation flux but also stable permeation behavior during the test process. The maximum CO2 permeation flux reaches up to 4.78, 5.46 and 1.79 ml min−1·cm−2 under the feed condition of 50%CO2–50%N2, 5%H2-47.5%CO2-47.5%N2 and 5%O2–20%CO2–75%N2, respectively, at 700 °C. These results are the highest CO2 permeation flux of the ceramic-carbonate membrane under the similar operation conditions in recent years. The excellent CO2 fluxes can be attributed to a unique and superior structure and a thinner thickness of the hollow fiber membrane. In addition, the membrane shows a stable time with 85 h during the long-term test process in a 50%CO2–50%N2 feed stream.

Coupling CO2 separation with catalytic reverse water-gas shift reaction via ceramic-carbonate dual-phase membrane reactor

Coupling of CO2 separation and CO2 utilization in membrane reactor is an ideal way to solve CO2 emission problem. In this study, we report an effective catalytic reverse water-gas shift (RWGS) process to produce CO with simultaneous CO2 capture from CO2-containing gas mixture using a ceramic-carbonate dual-phase membrane in a single reactor. The dual-phase membrane is comprised of a ceramic phase of oxygen-ion conductor and molten carbonate phase. The catalytic bed contains a LaNiO3 (LNO) or La0.9Ce0.1NiO3-δ (LCNO) catalyst. The RWGS reaction process can be catalytically activated by a single membrane without additional catalyst. CO2 permeation flux of the separation process and CO2 conversion of the RWGS reaction display significant increase after packing with catalysts in the membrane reactor. The results show that the reactor with LCNO catalyst generally precedes the LNO counterpart in CO2 conversion rate and the CO production yield. The membrane reactor yields a CO2 flux of 4.25 ml min−1 cm−2, which is around 4 times higher than that of the single membrane separation with pure He sweep gas. A CO2 conversion of 56.8% and a CO production rate of 2.41 ml min−1 cm−2 can be obtained at 750 °C using the membrane reactor with LCNO catalyst. Long-term stability test shows no obvious sign of degradation within 70 h. Overall, this work presents the technical exploration of a combined CO2 capture and conversion membrane-reactor for RWGS reaction process.

A novel study of sulfur-resistance for CO2 separation through asymmetric ceramic-carbonate dual-phase membrane at high temperature

Sulfur compounds present in high-temperature gases from various industrial sources have a negative influence on the permeability of different kinds of membranes. In this study, we present a general and efficient strategy to design and prepare two asymmetric membranes for CO2 separation that are resistant to H2S. The asymmetric membranes, mainly composed of one adsorbed layer for H2S consumption and one dense ceramic-carbonate layer for CO2 separation, show not only high CO2 permeation flux but also remarkably stable permeation behavior under an H2S-containing atmosphere. The sulfur-resistant stability times of the asymmetric membranes are approximately 10–12 times higher than the single ceramic-carbonate dual-phase membrane. The adsorbed layer of the asymmetric membranes can react with H2S to form Ce-O-S phases, gradually causing deactivation of the adsorbed layer. However, the adsorbed layer can be regenerated in the oxygen-containing gas stream above 850 °C, which can effectively remove the sulfur content from the adsorbed layer, making recycle of the membrane possible. Sulfur accumulated in the adsorbed layer of the membrane as a Ce2O2S phase, can be oxidized into SO2 under air stream and elemental sulfur (S) under a 2.5% O2/He gas stream. These asymmetric membranes thus possess high permeation stability in the H2S-containing atmosphere with good regenerability and also have potential in collection and removal of sulfur impurities from gas streams.

CO2 permeation through asymmetric thin tubular ceramic-carbonate dual-phase membranes

Ceramic-carbonate dual-phase dense membrane is a promising high temperature CO2 separation membrane with remarkable CO2 permeance and theoretically infinite CO2 selectivity. This paper reports synthesis and CO2 permeation properties of asymmetric tubular dual-phase membranes with a thin samarium doped ceria (Ce0.8Sm0.2O1.9, SDC)-carbonate separation layer and a thick porous SDC-Bi1.5Y0.3Sm0.2O3-δ (BYS) support. The asymmetric tubular thin (0.12 mm) dual-phase membrane has much higher CO2 permeance and lower activation energy for permeation than the thick (1.0–1.5 mm) membranes. At 900 °C with 50%CO2/N2 feed at 1 atm, the CO2 permeation flux and permeance for the thin membrane reach 1.53 × 10−2 mol m−2 s−1 (or 2.05 mL(STP) cm−2 min−1) and 3.16 × 10−7 mol m−2 s−1 Pa−1, respectively, with activation energy for permeation of 62.5 kJ/mol. These dual-phase membranes exhibit slightly higher CO2 permeance with essentially same activation energy for permeation, and stable operation, for CO2 permeation with simulated syngas (with the composition of 49.5%CO, 36%CO2, 4.5%N2, 10%H2) feed. The CO2 permeation fluxes of the tubular asymmetric membranes can be well described by the power-function flux equation. The analysis of CO2 permeation data with the model shows that the CO2 separation performance of the tubular asymmetric membranes can be further improved by optimizing the microstructure of ceramic porous supports. This work demonstrates that asymmetric SDC-carbonate dual-phase membrane has high potential for practical application in high temperature CO2 separation.

Poisoning Effect of H2S on CO2 Permeation of Samarium-Doped-Ceria/Carbonate Dual-Phase Membrane

CO2-permselective ceramic–carbonate dual-phase membranes offer potential for uses in separators or membrane reactors for conversion of coal derived syngas to hydrogen with CO2 capture. Coal derived syngas contains H2S, but the effect of H2S on permeation properties of these dual-phase membranes was unclear. This study examines the stability of Ce0.8Sm0.2O1.9 (SDC)–Li2CO3/Na2CO3 membrane in H2S-containing gas. CO2 permeation flux of the SDC–carbonate membrane is stable in a H2/N2/CO2 mixture gas, but it decreases after the introduction of H2S. The extent of the CO2 permeation flux reduction increases with H2S concentration in the feed gas and run time. Exposure to H2S results in appearance of a tree-branch-like structure near the feed side of the SDC–carbonate membrane, and formation of Ce2O2S on the SDC phase. Such an exposure has negligible effect on the carbonate phase. The formation of Ce2O2S lowers the oxygen ionic conductivity of the SDC phase, reducing the CO2 permeance for the dual-phase membrane.

Synthesis and characterization of gadolinium doped ceria-carbonate dual-phase membranes for carbon dioxide separation

Increased atmospheric CO2 concentration has caused severe environmental issues such as global warming and ocean acidification. In this work, Gd0.1Ce0.9O1.95-Li2CO3-Na2CO3 (GDC-LNC) ceramic-carbonate dual-phase membranes for electrochemical separation of CO2 were fabricated by a novel phase-inversion combined with carbonate solidification method. The Li/Na elements were left in the GDC ceramic due to the carbonation solution mixed with water as curing agent to solidify supports, which may modify the wettability of GDC with LNC. The maximum CO2 flux reached as much as 0.301 mL min−1cm−2 and the GDC-LNC dual-phase membranes exhibit stable CO2 permeation, suggesting a promising prospect towards future carbon storage and separation applications.

CO2-Tolerant SrFe0.8Nb0.2O3−δ–Carbonate Dual-Phase Multichannel Hollow Fiber Membrane for CO2 Capture

Ceramic–carbonate dual-phase membranes have attracted a lot of attention because of the emission of CO2 and environmental problems. In this study, a dense SrFe0.8Nb0.2O3−δ–carbonate dual-phase multichannel hollow fiber membrane has been successfully prepared via a phase inversion–sintering technique and impregnation. The morphology, crystal structure, phase stability, breaking load, and CO2 permeation flux of the as-prepared membranes were systematically investigated. The membrane not only had a higher CO2 permeation flux but also was of good thermomechanical stability in thermal recycles. Meanwhile, the membrane can be operated stably at 973 K over 200 h without any degradation of CO2 permeation flux. Our work demonstrates that the ceramic–carbonate dual-phase mixed-conducting multichannel hollow fiber membrane is a promising candidate for postcombustion CO2 capture.

Electrochemical Capture of CO2 from Natural Gas Using a High-Temperature Ceramic-Carbonate Membrane

This study reports the first investigation of using a ceramic-carbonate dual-phase membrane to electrochemically separate CO2 from a simulated natural gas. The CO2 permeation flux density was systematically studied as a function of temperature, CO2 partial pressure and time. As expected, the flux density was observed to increase with temperature and CO2 partial pressure. Long-term stability test showed that flux density experienced an initial performance-improving “break-in” period followed by a slow decay. Post-test microstructural analysis suggested that a gradual loss of carbonate during the test could be the cause of the flux-time behavior observed.

Ceramic–carbonate dual-phase membrane with improved chemical stability for carbon dioxide separation at high temperature

This study examines membrane synthesis, structural stability, permeation properties, and long-term permeation stability of a new dense dual-phase membrane of composition La0.85Ce0.1Ga0.3Fe0.65Al0.05O3 − δ (LCGFA)–carbonate for high temperature CO2 separation. Porous ceramic supports made by sintering pressed powder at a temperature below its densification temperature resulted in a desired support with an open porosity ranging between 40 and 50%. The dual-phase membranes was prepared by direct infiltration of the ceramic supports in molten carbonate at 600 °C, resulting in a four order of magnitude decrease in permeance when compared to the support. LCGFA–carbonate membranes are stable when exposed to gases ranging from gas mixtures containing N2 and various concentrations of CO2 to simulated syngas, and exhibit a stable long term CO2 permeation flux of 0.025 mL·min− 1·cm− 2 for more than 275 h at 900 °C. The CO2 permeation results show exponential dependence to increasing system temperature as well as a linear dependence to logarithmic change in CO2 partial pressure gradients across the membrane in the CO2 pressure range studied.

Effects of support pore structure on carbon dioxide permeation of ceramic-carbonate dual-phase membranes

Dual-phase membranes consisting of an ionic or mixed conducting ceramic phase and a molten carbonate phase are permeable only to carbon dioxide at high temperatures. This paper studies the effects of the pore structure of ceramic supports on carbon dioxide permeation properties of dual-phase membranes consisting of La0.6Sr0.4Co0.8Fe0.2O3−δ (LSCF) and eutectic Li2CO3–Na2CO3–K2CO3 carbonate phase. Porous LSCF supports with different pore structures were prepared by pressing LSCF powders followed by sintering at various temperatures. The porosity to tortuosity and solid fraction to tortuosity ratios for the porous LSCF supports were characterized by helium permeation and electrical conductivity measurements. The direct infiltration method allows complete filling of the ceramic support pores by the carbonate. CO2 permeance of the dual-phase membranes increases, and after reaching a maximum, decreases with increasing support sintering temperature or support porosity (carbonate fraction). A total conductance in terms of the effective carbonate and ionic conductivities (intrinsic conductivity modified by the carbonate or solid fraction to tortuosity ratio) is introduced and used to explain experimental results. The results show that the CO2 permeance of the dual-phase membrane is controlled not only by the intrinsic carbonate and oxygen ionic conductivities of the carbonate and ceramic phases, but also the carbonate or solid fraction to tortuosity ratio. Adjusting pore and solid microstructure of ceramic support is critical to maximize CO2 permeance of the dual-phase membranes.

Synthesis and characterization of thin ceramic-carbonate dual-phase membranes for carbon dioxide separation

Ceramic-carbonate dual-phase membranes are perm-selective to carbon dioxide at high temperatures. This paper reports a strategy to prepare thin ceramic-carbonate dual-phase membranes with improved carbon dioxide permeance. Two-layer asymmetric supports consisting of a large pore base support and a thin small pore ionic conducting ceramic top-layer were prepared for the thin dual-phase membranes. A dense thin ceramic-carbonate dual-phase membrane was successfully prepared on the asymmetric support containing carbonate non-wettable base with adequate mechanical bonding between the top-layer and base. The thin dual-phase membrane was constructed with a thin, small pore yttria-stabilized zirconia (YSZ) layer on a large pore Bi1.5Y0.3Sm0.2O3-δ (BYS) support. Li/Na/K molten carbonate mixture was infiltrated into the top YSZ layer via a direct infiltration method. Carbonate non-wettable BYS support stopped the penetration of carbonate and maintained its porous structure. By this way, a thin, dense ceramic-carbonate dual-phase membrane was prepared on a porous support after infiltration. High temperature CO2 permeation test was carried out for the membrane. CO2 permeance through the thin dual-phase membrane increased with temperature (500–650°C). At 650°C, maximum CO2 flux was 3.9×10−3molm−2s−1. The CO2 permeation activation energy is 106kJmol−1. The thin YSZ-carbonate dual-phase membrane offers much higher CO2 permeance than the reported thick dual-phase membranes. Reduction of the thickness hence lessening resistance and strengthening ionic transport should be the major reason.

Modeling and analysis of ceramic–carbonate dual-phase membrane reactor for carbon dioxide reforming with methane

A new high temperature tube–shell membrane reactor (MR) design for separation and utilization of CO 2 from the flue gas and for simultaneous production of syngas through carbon dioxide reforming of methane (CRM) is reported. The MR is based on a dual-phase CO 2 permeation membrane consisting of mixed-conducting oxide and molten carbonate phases. High temperature CO 2-containing flue gas and CH 4 are respectively fed into the shell and tube sides of the reactor packed with a reforming catalyst. Under performance conditions, CO 2 permeates selectively through the membrane from the shell side to the tube side and reacts with CH 4 to produce syngas. Additionally, the heat from the flue gas can transfer directly through the membrane to provide energy for the endothermic CRM reaction. An isothermal steady-state model was developed to simulate and analyze CRM in the MR in this work. The effect of the design and operational parameters, such as inlet CH 4 flow rate, shell side CO 2 partial pressure and the flue gas composition, i.e., containing O 2 or not, as well as the membrane thickness on the reactor performance with respect to the CH 4 conversion and the CO 2 permeation flux were investigated and discussed. The results show that the MR has a high efficiency in separating and utilizing CO 2 from the flue gas. For a CH 4 space velocity of 3265.31 h −1, with a membrane thickness of 0.075 mm and the shell side CO 2 partial pressure of 1 atm, a CH 4 conversion of 48.06% and an average CO 2 permeation flux of 1.52 mL(STP) cm −2 min −1 through the membrane tube at 800 °C are obtained. Further improvement of the MR performance can be achieved by involving O 2 in the permeation process.