Novel fixed‐carrier membranes for CO2 separation

A new membrane material having two kinds of CO₂ carriers was obtained. Composite membranes were prepared with the material and support membranes. The facilitated transport of CO₂ through these membranes was performed with pure CH₄ and CO₂ as well as CH₄/CO₂ mixtures containing 50 vol % CO₂. The results show that the membranes possess better CO₂ permeance than that of other fixed carrier membranes reported in the literature. In the measurements with pure gases, at 26°C, 0.013 atm of CO₂ pressure, the membrane with polysulfone support displays a CO₂ permeance of 7.93 × 10^?4 cm³ /cm² s cmHg and CO₂/CH₄ ideal selectivity of 212.1. In the measurements with mixed gases, at 26°C, 0.016 atm of CO₂ partial pressure, the membrane displays a CO₂ permeance of 1.69 × 10^?4 cm³ /cm² s cmHg and CO₂/CH₄ selectivity of 48.1. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2222–2226, 2002     

Preparation of polyvinylamine/polysulfone composite hollow‐fiber membranes and their CO2/CH4 separation performance

Fixed‐carrier composite hollow‐fiber membranes were prepared with polyvinylamine (PVAm) as the selective layer and a polysulfone ultrafiltration membrane as the substrate. The effects of the PVAm concentration in the coating solution, the number of coatings, and the crosslinking of glutaraldehyde and sulfuric acid on the CO₂ permeation rate and CO₂/CH₄ selectivity of the composite membranes were investigated. As the PVAm concentration and the number of coatings increased, the CO₂/CH₄ selectivity increased, but the CO₂ permeation rate decreased. The membranes crosslinked by glutaraldehyde or sulfuric acid possessed higher CO₂/CH₄ selectivities but lower CO₂ permeation rates. For the pure feed gas, a composite hollow‐fiber membrane coated with a 2 wt % PVAm solution two times and then crosslinked with glutaraldehyde and an acid solution in sequence had a CO₂ permeation rate of 3.99 × 10^?6 cm³ cm^?2 s^?1 cmHg^?1 and an ideal CO₂/CH₄ selectivity of 206 at a feed gas pressure of 96 cmHg and 298 K. The effect of time on the performance of the membranes was also investigated. The performance stability of the membranes was good during 6 days of testing. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1885–1891, 2006     

Gas permeation properties of new type asymmetric membranes

We have developed a new type of asymmetric membranes having a homogeneous hyperthin skin layer, which was used as a polyimide synthesized by 2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and 2,2-bis(4-amino phenyl) hexafluoro-propane (BAAF). The skin layer thicknesses of the 6FDA-BAAF polyimide asymmetric membranes were 40–60 nm, and the porosity was 10^-6% when a defect size was assumed as 5 nm. The permselectivity of 6FDA-BAAF polyimide asymmetric membranes after silicone coating had α of 40 for CO₂/CH₄ and a flux of 1.0 [Nm³/m²-h-atm] (=3.7 × 10⁻⁴ [cm³(STP)/cm² s cmHg]) for CO₂, α of 4.3 for O₂/N₂ and a flux of 2.0 × 10⁻¹ [Nm³/m²/h/atm] (=7.1 × 10⁻⁵ [cm³(STP)/cm²s cmHg]) for O₂. These values were constant for large-scale manufacturing. © 1996 John Wiley & Sons, Inc.     

Gas permeability and selectivity through asymmetric polyimide membranes

Permeability and selectivity of CO₂, O₂, N₂, and CH₄ were determined for the asymmetric membrane of aromatic polyimide derived from 2,2′-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and 3,3′-diaminodiphenylsulfone (m-DDS) at 35°C and at pressure up to 76 cmHg. The average apparent skin layer thickness of all asymmetric membranes measured was 2.6 μm. The selectivities for (O₂/N₂) and (CO₂/CH₄) in the membranes were 11.5 at O₂ permeance of 3.2 × 10⁻⁷ and 153 at CO₂ of 6.3×10⁻⁷ [cm³(STP)/cm² s cmHg], respectively, without the necessity of an additional coating process. The average gas selectivities of the asymmetric memberanes were much larger than those determined for the dense membrances. The effect of the microstructure of polyimide on the gas selectivity is discussed. © 1996 John Wiley & Sons, Inc.     

New high permeable polysulfone/ionic liquid membrane for gas separation

In this study, the effects of 1-Ethyl-3-methylimidazolium tetrafluoroborate ionic liquid on CO₂/CH₄ separation performance of symmetric polysulfone membranes are investigated. Pure polysulfone membrane and ionic liquid-containing membranes are characterized. Field emission scanning electron microscopy (FE-SEM) is used to analyze surface morphology and thickness of the fabricated membranes. Energy dispersive spectroscopy (EDS) and elemental mapping, Fourier transform infrared (FTIR), thermal gravimetric (TGA), X-ray diffraction (XRD) and Tensile strength analyses are also conducted to characterize the prepared membranes. CO₂/CH₄ separation performance of the membranes are measured twice at 0.3 MPa and room temperature (25 °C). Permeability measurements confirm that increasing ionic liquid content in polymer-ionic liquid membranes leads to a growth in CO₂ permeation and CO₂/CH₄ selectivity due to high affinity of the ionic liquid to carbon dioxide. CO₂ permeation significantly increases from 4.3 Barrer (1 Barrer=10^-10 cm³(STP)·cm·cm^-2·s^-1·cmHg^-1, 1cmHg=1.333kPa) for the pure polymer membrane to 601.9 Barrer for the 30 wt% ionic liquid membrane. Also, selectivity of this membrane is improved from 8.2 to 25.8. mixed gas tests are implemented to investigate gases interaction. The results showed, the disruptive effect of CH₄ molecules for CO₂ permeation lead to selectivity decrement compare to pure gas test. The fabricated membranes with high ionic liquid content in this study are promising materials for industrial CO₂/CH₄ separation membranes.     

Preparation of vinyl amine‐co‐vinyl alcohol/polysulfone composite membranes and their carbon dioxide facilitated transport properties

A vinyl amine–vinyl alcohol copolymer (VAm–VOH) was synthesized through free‐radical polymerization, basic hydrolysis in methanol, acidic hydrolysis in water, and an anion‐exchange process. In the copolymer, the primary amino groups on the VAm segment acted as the carrier for CO₂‐facilitated transport, and the vinyl alcohol segment was used to reduce the crystallinity and increase the gas permeance. VAm–VOH/polysulfone (PS) composite membranes for CO₂ separation were prepared with the VAm–VOH copolymer as a selective layer and PS ultrafiltration membrane as a support. The membrane gas permselectivity was investigated with CO₂, N₂, and CH₄ pure gases and their binary mixtures. The results show that the CO₂ transport obeyed the facilitated transport mechanism, whereas N₂ and CH₄ followed the solution–diffusion mechanism. The increase in the VAm fraction in the copolymer resulted in a carrier content increase, a crystallinity increase, and intermolecular hydrogen‐bond formation. Because of these factors, the CO₂ permeance and CO₂/N₂ selectivity had maxima with the VAm fraction. At an optimum applied pressure of 0.14 MPa and at an optimum VAm fraction of 54.8%, the highest CO₂ permeance of 189.4 GPU [1 GPU = 1 × 10^?6 cm³(STP) cm^?2 s^?1 cmHg^?1] and a CO₂/N₂ selectivity of 58.9 were obtained for the CO₂/N₂ mixture. The heat treatment was used to improve the CO₂/N₂ selectivity. At an applied pressure of 0.8–0.92 MPa, the membrane heat‐treated under 100°C possessed a CO₂ permeance of 82 GPU and a CO₂/N₂ selectivity of 60.4, whereas the non‐heat‐treated membrane exhibited a CO₂ permeance of 111 GPU and a CO₂/N₂ selectivity of 45. After heat treatment, the CO₂/N₂ selectivity increased obviously, whereas the CO₂ permeance decreased. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 40043.     

Tuning the gas separation performance of fluorinated and sulfonated PEEK membranes by incorporation of zeolite 4A

Mixed matrix membranes (MMMs) containing fluorinated‐sulfonated poly(ether ether ketone) (F‐SPEEK) and zeolite 4A filler, were prepared by solution casting. F‐SPEEK with a fixed degree of sulfonation (40%) was used for membrane synthesis. The SEM pictures showed good interfacial adhesion between filler particles and polymer, which was also confirmed by the increase in glass transition temperature of MMMs with increase in filler particles. Pure and mixed gas permeation experiments were carried out to investigate the potential of this membrane material. The results revealed that addition of zeolite 4A fillers enhanced both permeability and selectivity owing to the intrinsic nature of polymer and modified membrane morphology due to filler. The highest permeability obtained for CO₂ at 30% filler loading was 49.2 Barrer, while highest selectivities obtained for CO₂/CH₄ and CO₂/N₂ were 55 and 58 compared to 47 and 51 for the unfilled polymer, respectively. Intrinsic CO₂ solubility of F‐SPEEK was observed to be decreased from 10.7 to 1.9 (10^?2) cm³ (STP)/cm³ cmHg with the addition of Zeolite 4A. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45952.     

Synthesis of dual-functionalized mixed matrix membrane with amino-GO-Bent/PVDF for efficient separation of CO2/CH4 and CO2/N2

Mixed matrix membranes (MMMs), which combine the characteristics of inorganic nanofillers and organic matrices, have received wide attention because of their good permeability and selective performance for separating CO₂ from industrial waste gases. In this work, the amino-GO-loaded bentonite (amino GO-Bent) was prepared by loading  NH₂ on the GO surface with a large number of functional sites. Firstly, by introducing  NH₂ on the surface of GO and then interacting with bentonite (Bent) organically modified by silane coupling agents through amide bonding. Mixed matrix membranes (MMMs) with an area of 623.7 cm² and homogeneous texture were prepared using amino-GO-Bent as inorganic filler to improve the membrane selectivity for CO₂/N₂ and CO₂/CH₄ separation. The results show that the introduction of amino GO-Bent in MMMs can greatly improve the CO₂ permeability and obtain high CO₂ permeation performance: 2.67945 × 10⁻⁷ cm³ (STP)·cm/s/cm²/cmHg, and the selectivity of CO₂/N₂ and CO₂/CH₄ can reach 307.28 and 325.97, respectively. The two selective values were 14 and 18 times higher than those of pure PVDF membranes, and the performance of MMMs far exceeded the Robeson upper limit in 2008, respectively.     

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 CO₂‐stable oxide hollow‐fiber membranes based on (Pr_0.9La_0.1)₂(Ni_0.74Cu_0.21Ga_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, CH₄ concentration and flow rate of the feed air on CH₄ conversion, CO selectivity, H₂/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 cm² and the CO selectivity is higher than 99.5% with a CH₄ conversion of 97.0% and a H₂/CO ratio of 1.8 during 140 h steady operation. The spent hollow‐fiber membrane still maintains a dense microstructure and the Ruddlesden‐Popper K₂NiF₄‐type structure, which indicates that the U‐shaped alkaline‐earth metal‐free CO₂‐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     

Gas permeation and separation properties of sulfonated polyimide membranes

Permeability and selectivity of pure gas H₂, CO₂, O₂, N₂ and CH₄ as well as a mixture of CO₂/N₂ for sulfonated homopolyimides prepared from 1,4,5,8-naphthalene tetracarboxylic dianhydride (NTDA) and 2,2-bis[4-(4-aminophenoxy)phenyl] hexafluoro propane disulfonic acid (BAPHFDS) were measured and compared to those of the non-sulfonated homopolyimide having the same polymer backbone. The polyimide in a proton form (NTDA-BAPHFDS(H)) displayed higher selectivity of H₂ over CH₄ without loss of H₂ permeability. Strong intermolecular interaction induced by sulfonic acid groups decreased diffusivity of the larger molecules. The CO₂/N₂ (19/81) mixed gas permeation was investigated as a function of humidity. With increasing relative humidity from 0% RH to 90% RH, the CO₂ permeability for NTDA-BAPHFDS(H) polyimide increased by more than one order of magnitude, and the selectivity of CO₂/N₂ also increased twice or more. On the other hand, the gas permeability for the non-sulfonated polyimide slightly decreased with increasing humidity. NTDA-BAPHFDS(H) polyimide displayed a CO₂ permeability of 290×10⁻¹⁰ cm³ (STP) cm/(cm² s cmHg) and a separation factor of CO₂/N₂ of 51 at 96% RH, 50 °C and total pressure of 1 atm.     

Carbon dioxide separation and dry reforming of methane for synthesis of syngas by a dual‐phase membrane reactor

High‐temperature CO₂ selective membranes offer potential for use to separate flue gas and produce a warm, pure CO₂ stream as a chemical feedstock. The coupling of separation of CO₂ by a ceramic–carbonate dual‐phase membrane with dry reforming of CH₄ to produce syngas is reported. CO₂ permeation and the dry reforming reaction performance of the membrane reactor were experimentally studied with a CO₂–N₂ mixture as the feed and CH₄ as the sweep gas passing through either an empty permeation chamber or one that was packed with a solid catalyst. CO₂ permeation flux through the membrane matches the rate of dry reforming of methane using a 10% Ni/γ‐alumina catalyst at temperatures above 750°C. At 850°C under the reaction conditions, the membrane reactor gives a CO₂ permeation flux of 0.17 mL min^?1 cm^?2, hydrogen production rate of 0.3 mL min^?1 cm^?2 with a H₂ to CO formation ratio of about 1, and conversion of CO₂ and CH₄, respectively, of 88.5 and 8.1%. © 2013 American Institute of Chemical Engineers AIChE J, 59: 2207–2218, 2013     

Fabrication of 6FDA‐durene polyimide asymmetric hollow fibers for gas separation

We have developed defect‐free asymmetric hexafluoro propane diandydride (6FDA) durene polyimide (6FDA‐durene) hollow fibers with a selectivity of 4.2 for O₂/N₂ and a permeance of 33.1 ×10^?6 cm³ (STP)/cm²‐s‐cmHg for O_2. These fibers were spun from a high viscosity in situ imidization dope consisting of 14.7% 6FDA‐durene in a NMP solvent and the inherent viscosities (IV) of this 6FDA‐durene polymer was 0.84 dL/g. Low IV dopes cannot produce defect‐free hollow fibers, indicating a 6FDA‐durene spinning dope with a viscosity in the region of chain entanglement seems to be essential to yield hollow fibers with minimum defects. The effects of spinning parameters such as shear rates within a spinneret and bore fluids as well as air gap on gas separation performance were investigated. Experimental data demonstrate that hollow fibers spun with NMP/H₂O as the bore liquid have higher permeances and selectivities than those spun with glycerol as the bore liquid because the former has a relatively looser inner skin structure than the latter. In addition, the selectivity of hollow fibers spun with NMP/H₂O as the bore liquid changes moderately with shear rate, while the selectivity of hollow fibers spun with glycerol are less sensitive to the change of shear rate. These distinct behaviors are mainly attributed to the different morphologies generated by different bore fluids. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2166–2173, 2001     

Preparation and characterization of microporous polyethylene hollow fiber membranes

Microporous polyethylene (PE) hollow fiber membrane with a porosity of 43% and N₂ permeation of 4.96 cm³ (STP)/cm² s cmHg was prepared by melt‐spinning and cold‐stretching method. It was found that PE with a density higher than 0.96 g/cm³ should be used for the preparation of microporous PE hollow fiber membranes. By increasing the spin–draw ratio, both the porosity and the N₂ permeation of the hollow fiber membranes increased. Annealing the nascent hollow fiber at 115°C for 2 h was suitable for attaining membranes with good performance. By straining the hollow fiber to higher extensions, the amount and size of the micropores in the hollow fiber wall increased, and the N₂ permeation of the membranes increased accordingly. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 203–210, 2002; DOI 10.1002/app.10305     

Hybrid FSC membrane for CO2 removal from natural gas: Experimental,process simulation,and economic feasibility analysis

The novel fixed‐site‐carrier (FSC) membranes were prepared by coating carbon nanotubes reinforced polyvinylamine/polyvinyl alcohol selective layer on top of ultrafiltration polysulfone support. Small pilot‐scale modules with membrane area of 110–330 cm² were tested with high pressure permeation rig. The prepared hybrid FSC membranes show high CO₂ permeance of 0.084–0.218 m³ (STP)/(m² h bar) with CO₂/CH₄ selectivity of 17.9–34.7 at different feed pressures up to 40 bar for a 10% CO₂ feed gas. Operating parameters of feed pressure, flow rate, and CO₂ concentration were found to significantly influence membrane performance. HYSYS simulation integrated with ChemBrane and cost estimation was conducted to evaluate techno‐economic feasibility of a membrane process for natural gas (NG) sweetening. Simulation results indicated that the developed FSC membranes could be a promising candidate for CO₂ removal from low CO₂ concentration (10%) NGs with a low NG sweetening cost of 5.73E?3 $/Nm³ sweet NG produced. © 2014 American Institute of Chemical Engineers AIChE J 60: 4174–4184, 2014     

Gas permeation properties of poly(2,5‐benzimidazole) derivative membranes

In this article, three novel polymers based on poly(2,5‐benzimidazole) (ABPBI) were synthesized by introducing propyl, isobutyl or n‐butyl groups to its side chain through an alkyl substitution reaction. FTIR and ¹³C NMR were applied to confirm the formation of corresponding chemical groups. Their physical properties including crystallinity, thermal stability, mechanical strength, and micro‐morphology were also characterized. Their solubility in common solvents were also tested to see if the modification will bring any improvement. Gas permeation properties of three derivative membranes prepared by a casting and solvent‐evaporation method were tested with pure gases including H₂, N₂, O_2, CH₄, and CO₂. It has been revealed that gas with a smaller molecular size owned a larger permeability. This means gas permeation in all prepared membranes should be diffusivity selective. Among all three modified ABPBI membranes, isobutyl substitution modified ABPBI (IBABPBI) showed the best selectivity of H₂ over other gases such as N₂ (～185) and CO₂ (～6.3) with a comparable permeability (～9.33 barrer) when tested at 35°C and 3.0 atm. Testing temperature increase facilitated gas permeation for all three membranes obviously; while in term of gas selectivity temperature increase showed diverse alteration because it brought variable impact on gas solubility of different gases. Even so, IBABPBI membrane still owned acceptable selectivity of H₂ over N₂ (～118) and CO₂ (～6.3) with an almost doubled permeability (～17.5 barrer) when tested at 75°C and 3.0 atm. Additional tests showed that running at high pressure did not bring any obvious deterioration to gas separation performance of IBABPBI membrane. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40440.     

Preparation and characterization of sulfonated block‐graft copolyimide/sulfonated polybenzimidazole blend membranes for fuel cell application

Polymer electrolyte blend membranes composed of sulfonated block‐graft polyimide (S‐bg‐PI) and sulfonated polybenzimidazole (sPBI) were prepared and characterized. The proton conductivity and oxygen permeability coefficient of the novel blend membrane S‐bg‐PI/sPBI (7 wt%) were 0.38 S cm^?1 at 90 °C and 98% relative humidity and 7.2 × 10^?13 cm³(STP) cm (cm² s cmHg)^?1 at 35 °C and 76 cmHg, respectively, while those of Nafion^® were 0.15 S cm^?1 and 1.1 × 10^?10 cm³(STP) cm (cm² s cmHg)^?1 under the same conditions. The apparent (proton/oxygen transport) selectivity calculated from the proton conductivity and the oxygen permeability coefficient in the S‐bg‐PI/sPBI (7 wt%) membrane was 300 times larger than that determined in the Nafion membrane. Besides, the excellent gas barrier properties based on an acid ? base interaction in the blend membranes are expected to suppress the generation of hydrogen peroxide and reactive oxygen species, which will degrade fuel cells during operation. The excellent proton conductivity and gas barrier properties of the novel membranes promise their application for future fuel cell membranes. © 2015 Society of Chemical Industry     

Polysulfone membranes containing ethylene glycol monomers: synthesis,characterization, and CO<Subscript>2</Subscript>/CH<Subscript>4</Subscript> separation

Copolymers based on glassy and rubbery units have been developed to take advantage of both domains to enhance solubility and diffusivity. In this study, a series of gas separation membranes from polysulfone (PSF) containing ethylene glycol were synthesized via nucleophilic substitution polycondensation. The structures of copolymers were characterized by nuclear magnetic resonance spectra, Fourier transform infrared spectra, and thermal gravity analysis. The permeability and selectivity of the membranes were studied at different temperatures of 25–55 °C and pressures of 0.5–1.5 atm using single gases CO₂ and CH₄. Gas permeation measurements showed that copolymers with different contents of poly(ethylene glycol) exhibited different separation performances. For example, the membrane from PSF-PEG2000-20 containing 20 wt% poly(ethylene glycol) showed better performance in terms of ideal selectivity over the other seven copolymer membranes. The highest ideal CO₂/CH₄ selectivity was 43.0 with CO₂ permeability of 6.4 Barrer at 1.5 atm and 25 °C.     

PVAm/PAN复合膜的制备及其对CO2/CH4的分离性能

New polymeric membrane materials——polyvinyl amine (PVAm) with different primary amine contents were synthesized.By covering polyacrylonitrile(PAN) ultrafiltration membranes with PVAm, the PVAm/PAN composite membranes for CO₂/CH₄ separation were prepared. The composite membranes containing more primary amino groups have higher selectivity for CO₂/CH₄.The cross-linking of acid or glutaradehyde could improve the gas permselectivity of the composite membranes. With decreasing CO₂ content in the feed gas, the CO₂/CH₄ separation factor increased.When the feed gas was 25%(vol) CO₂ and 75%(vol) CH₄, the CO₂ permeation rate was 4.1×10^-9cm³(STP) &#8226;cm^-2&#8226;Pa^-1&#8226;s^-1, and the CO₂/CH₄ separation factor was 180.     

Optimization of CO2–CH4 separation performance of integrally skinned asymmetric membranes prepared from poly(2,6‐dimethyl‐1,4‐phenylene oxide) by factorial design

Integrally skinned asymmetric flat sheet membranes were prepared from poly(2,6‐dimethyl 1,4‐phenylene oxide)(PPO) for CO₂–CH₄ separation. Various experiments were carried out to identify PPO membranes, which have good mechanical strength and gas separation abilities. Membrane strength and selectivity depend on the interplay of the rate of precipitation and the rate of crystallization of the PPO. The effects of major variables involved in the membrane formation and performance, including the concentration of the polymer, solvent, and additive, the casting thickness, the evaporation time before gelation, and the temperature of the polymer solution, were investigated. Factorial design experiments were carried out to identify the factor effects. The membrane performance was modelled and optimized to approach preset values for high CO₂ permeance and a high CO₂ : CH₄ permeance ratio. Membranes were prepared based on the optimum conditions identified by the model. Essentially, defect‐free membranes were prepared at these conditions, which resulted in a pure gas permeance of 9.2 × 10⁻⁹ mol/m² s Pa for CO₂ and a permeance ratio of 19.2 for CO₂ : CH₄. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1601–1610, 1999     

A novel porous‐dense dual‐layer composite membrane reactor with long‐term stability

A porous‐dense dual‐layer composite membrane reactor was proposed. The dual‐layer composite membrane composed of dense 0.5 wt % Nb₂O₅‐doped SrCo_0.8Fe_0.2O_3‐δ (SCFNb) layer and porous Ba_0.3Sr_0.7Fe_0.9Mo_0.1O_3‐δ (BSFM) layer was prepared. The stability of SCFNb membrane reactor was improved significantly by the porous‐dense dual‐layer design philosophy. The porous BSFM surface‐coating layer can effectively reduce the corrosion of the reducing atmosphere to the membrane, whereas the dense SCFNb layer permeated oxygen effectively. Compared with single‐layer dense SCFNb membrane reactor, no degradation of performance was observed in the dual‐layer membrane reactor under partial oxidation of methane during continuously operating for 1500 h at 850°C. At 900°C, oxygen flux of 18.6 mL (STP: Standard Temperature and Pressure) cm^?2 min^?1, hydrogen production of 53.67 mL (STP) cm^?2 min^?1, CH₄ conversion of 99.34% and CO selectivity of about 94% were achieved. © 2013 American Institute of Chemical Engineers AIChE J, 59: 4355–4363, 2013