Received: 12 May 2023 Revised: 20 July 2023 Accepted: 20 July 2023 DOI: 10.1111/jace.19411 F INAL I ST ART ICLE Perspectives on achievements and challenges of oxygen transport dual-functional membrane reactors Guoxing Chen1 Marc Widenmeyer2 Xiao Yu1 Ning Han3 Xiaoyao Tan4 Gert Homm1 Shaomin Liu4 AnkeWeidenkaff1,2 1Fraunhofer Research Institution for Materials Recycling and Resource Strategies IWKS, Alzenau, Germany 2Department of Materials and Earth Sciences, Technical University Darmstadt, Darmstadt, Germany 3Department of Materials Engineering, KU Leuven, Leuven, Belgium 4State Key Laboratory of Separation Membranes and Membrane Processes, School of Chemical Engineering, Tiangong University, Tianjin, China Correspondence Guoxing Chen, Fraunhofer Research Institution for Materials Recycling and Resource Strategies IWKS, Brentanostraße 2a, 63755 Alzenau, Germany. Email: guoxing.chen@iwks.fraunhofer.de Editor’s Choice The Editor-in-Chief recommends this outstanding article Funding information Federal Ministry of Education and Research, Grant/Award Number: 03SF0618B; PiCK project, Grant/Award Number: 03SFK2S3B Abstract The integration of membrane separation processes with chemical reactions through oxygen transport dual-functional membrane reactors has attracted sig- nificant attention due to the potential for process intensification, which also can create a synergy between the two units. This approach holds promise for promoting green chemistry principles by reducing energy consumption and envi- ronmental pollution. Despite its potential, a comprehensive review of recent advancements exploring the full potential of oxygen transport dual-functional membrane reactors (coupling two distinct reactions) in enhancing membrane performance is currently lacking. To address this gap, this perspective article presents various concepts and principles of oxygen transport dual-functional membrane reactors and provides an overview of recent advances and appli- cations. Additionally, the challenges and opportunities for future research to enhance the efficiency of the process toward industrialization are discussed and highlighted. These include developing novel oxygen transport membrane mate- rials, optimizing membrane engineering, innovating membrane reactor design, and exploring new applications and reaction mechanisms. KEYWORDS membranes, perovskites, thermal decomposition 1 INTRODUCTION Membrane separation technology has received increasing attentionworldwide due to its energy saving feature.Mem- brane reactors can integrate reaction and separation pro- cesses in a single unit, which can significantly enhance the performance (conversion, selectivity, and yield) of these This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes. © 2023 The Authors. Journal of the American Ceramic Society published by Wiley Periodicals LLC on behalf of American Ceramic Society. equilibrium-limited reactions. Such a chemical process intensification technology possesses obvious advantages compared with conventional multistep systems—such as lower energy requirements, reducing system volume, the possibility of heat integration, and safer operation.1,2 Mem- brane reactor technology has been the focus of research for many years, but it is still in a developing stage due 1490 wileyonlinelibrary.com/journal/jace J Am Ceram Soc. 2024;107:1490–1504. https://orcid.org/0000-0002-1570-4639 mailto:guoxing.chen@iwks.fraunhofer.de http://creativecommons.org/licenses/by-nc/4.0/ https://wileyonlinelibrary.com/journal/jace CHEN et al. 1491 to the need for highly stable membrane materials that can withstand the oxidizing or reducing reaction environ- ments at high temperatures. Currently, commercial-scale membrane reactors can be found in biochemical pro- cesses that operate at temperatures lower than 60◦C,where polymeric membranes are suitable for use.3 However, for petrochemical industry processes that occur at tempera- tures higher than 800◦C, inorganic or ceramic membranes are required instead of polymeric ones. Coincidently, dense ion conducting perovskite oxide ceramic mem- branes exhibit high oxygen permeation flux and can be used as membrane reactors for high-temperature oxida- tions. In comparison to pure ion conducting membranes, mixed ionic and electronic conducting (MIEC) ceramics can simplify the design of the membrane reactor without the need for an external circuit. The MIEC oxygen transport membrane (OTM) reactors generally can be classified as oxygen distributor- or oxygen extractor-type based on the different roles they serve. As an oxygen distributor, the membrane allows oxygen in the feed gas of air to permeate through and be distributed uni- formly for participating in oxidation reactions. The most common applications are partial oxidation of methane (POM) to syngas, selective oxidation of ammonia, oxida- tive coupling of methane (OCM) to C2 hydrocarbons, and oxidative dehydrogenation of light alkanes to olefins. In the case of oxygen extractor-type OTM reactor, oxygen can be in situ extracted from a reaction mixture on one mem- brane side to shift the reaction to the desirable product side. These reactions include CO2 decomposition, nitric oxide decomposition, and water splitting (WS). There have been numerous reviews that provide in-depth summaries of the applications of these two types of OTM reactors.1,4–8 In recent years, there has been growing interest in cou- pling two distinct reactions through an OTM reactor to speed up chemical reactions due to advancements in the stability of membrane materials.8–11 The coupling reaction can be accomplished by decomposing oxygen-containing gases (e.g., H2O and CO2) in combination with another oxidative process for improving the oxygen extraction effi- ciency such as POM. In order to accelerate the reaction rate of some specific reactions, it is necessary to load addi- tional catalysts on the membrane surface. The optimal amounts of catalyst loading and catalyst interaction mode with the membrane reactors are essential for maximiz- ing OTM reactor performance. The potential of oxygen transport dual-functional membrane reactors (coupling two distinct reactions) as an effective measure of enhanc- ingmembrane performance has yet to be fully explored in a comprehensive reviewof recent advances. This perspective paper aims to bridge this gap by providing a critical analy- sis of the latest progress in coupling two chemical reactions using an OTM reactor, as well as outlining current limi- tations and future challenges in the practical application of this technology. To this end, we present an overview of recent developments and discuss various aspects that require further investigation, such as the development of novel OTM materials, optimization of membrane engi- neering, and innovation in membrane reactor design, as well as exploring new applications and reaction mechanisms. 2 RECENT ACHIEVEMENTS AND FUTURE CHALLENGES Combining two distinct reactions through the implemen- tation of an OTM reactor presents an efficient approach to enhance the speed and efficiency of chemical processes. By employing an OTM, oxygen ions can be transported from one reaction site to another, enabling simultaneous reactions and minimizing the reliance on external oxy- gen supply. The underlying principle involves utilizing the OTM to transfer oxygen ions generated in an oxygen- producing reaction to a separate reaction site where they react with a fuel gas, leading to the production of the desired chemical product. This configuration allows the two reactions to take place on opposite sides of the OTM reactor. An important advantage of coupling these dis- tinct reactions through an OTM reactor is the considerable increase in yield and selectivity of the desired product. Hollow fiber membranes, known for their high oxy- gen permeability, have been extensively investigated and implemented in oxygen transport dual-functional mem- brane reactors.2 The coupling of reactions can be achieved by the dissociation of oxygen-containing gases (e.g., H2O, CO2, and NOx) in combination with other oxidative pro- cesses like the POMas shown inFigure 1. The development of suitable OTM materials tailored to specific applications necessitates varying specifications. This section provides an overview of recent advancements and offers insights into several aspects that require further investigation in this field. 2.1 Water splitting coupling with oxidative process WS for hydrogen production has been an active area of research for many years. Although photocatalysis using solar energy has been extensively investigated, the low efficiency of these semiconductor catalysts has limited their practical applications.1,2 Alternative methods, such as electrolysis or direct thermal water decomposition, have been explored.1,2 However, conventional reactors face challenges due to the low equilibrium constant for H2 1492 CHEN et al. F IGURE 1 Schematic diagram of oxygen transport dual-functional membrane reactor for coupling dissociation of oxygen-containing gases (e.g., H2O, CO2, and NOx) with an oxidative process (e.g., partial oxidation of methane [POM] and oxidative coupling of methane [OCM]). production from water dissociation. The use of mem- brane reactors can significantly improve H2 generation by shifting the equilibrium through the removal of one of the products, namely, oxygen. Caro et al. tested their BaCoxFeyZr1−x−yO3−δ hollow fibermembrane forWS cou- pling with POM.12 The observed H2 production rate at 950◦C was 0.7 mL cm−2 min−1. It is worth noting that the use of an inert sweep gas (helium) would result in a very low H2 production rate of less than 0.025 mL cm−2 min−1 unless highly reducing gases such as CO, H2, CH4, or C2H6 are added to rapidly consume the oxygen in the perme- ate side.13 In solely the viewpoint of H2 production, CO or H2 is a better reductant than others as its reaction with oxygen is more exothermic and spontaneous, thus, can efficiently lower the oxygen partial pressure in the per- meate side. Some researchers are using waste H2 to get pure H2 by condensing unreacted steam.1,2,7,14 Many other researchers are more interested in coupling with an oxida- tive process reaction to get more useful products from the membrane reactors.1,7 The H2 production rate is strongly associatedwith the oxygen consumption rate in the perme- ate side for fast oxygen extraction in the water dissociation side. For a better performance, Jiang et al. modified the BaCoxFeyZr1−x−yO3−δ (BCFZ) membrane surface by coating a catalytically active BaCoxFeyZr0.9−x−yPd0.1O3−δ (BCFZ-Pd) porous layer for POM.15 This modification increased the membrane’s oxygen extraction capability 3.5 times relative to the original BCFZ membrane, lead- ing to an increase in H2 production rate from 0.7 to 2.1mL cm−2 min−1 at 950◦C. Another approach to improve H2 production is to increase the reaction kinetics of POM, for example, by packing a catalyst. Jiang et al. reportedWS in a BCFZ hollow fiber membrane (thickness 0.17 mm) packed with Ni-based catalysts surrounding the hollow fiber for POM reaction.13 At 950◦C, the H2 forming rate was further improved to 3.1 mL cm−2 min−1 with a CH4 conversion of 70% and CO selectivity of 60%. These results are very inspiring, but the most challenging issue is the poor membrane stability of Co/Fe-containing perovskite oxides as the cobalt or iron components are easily reduced to metal phase. The cobalt or iron leaching out from the perovskite lattice would definitely have a negative influ- ence on the oxygen transport but may provide a catalytic effect on WS, details of which have not been reported. To overcome the poor stability issue of Co-containing perovskite oxides, Fang et al. investigated WS coupled with POM using a more robust dual-phase MIEC disk- shaped membrane composed of Ce0.85Sm0.15O1.925 (SDC) and Sm0.6Sr0.4Al0.34Fe0.7O3−δ (SSAF)with a sandwich-like symmetrical structured catalyst on eachmembrane side to promote both reactions (WS and POM).16 As anticipated, the H2 production rate could reach 11.7 mL min−1 cm−2 due to the improved catalytic efficiency for both reactions. More importantly, themembrane reactor couldmaintain a stable performance over 100-h-operation, which indicates a good chemical stability under conditions suitable for WS and POM. Coupling water decomposition in combination with other oxidative processes has also been studied. A novel coupling reaction process for H2 production is reported by Zhu et al., where WS is combined with ethanol oxida- tive steam reforming in a tubular SrCo0.4Fe0.5Zr0.1O3−δ (SCFZ) membrane reactor.17 At 750◦C, hydrogen produc- tion rates of 6.8 and 1.8 mL min−1 cm−2 were achieved for ethanol oxidative steam reforming and water decom- position on the two sides of the OTM, respectively. Cao et al. reported their results of WS coupling with OCM in a novel asymmetric Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF)mem- brane consisting of a dense top layer (70 μm in thickness) and thick porous support layer (830 μm in thickness) with 34% open porosity.18 Methane oxidative coupling was tested in the dense membrane side with an Mn–Na2WO4 catalyst deposition, and steam was fed to the porous BSCF side. At 950◦C, anH2 production rate of 3.3mL cm−2 min−1 with 26% of CH4 conversion and 6.5% C2 selectivity was achieved. There is no doubt that the porous BSCF layer added a catalytic effect to the WS reaction; however, the stability of BSCF membrane is an issue. Jiang et al. stud- iedWS coupling with oxidative dehydrogenation of ethane CHEN et al. 1493 (ODE) in a BCFZ hollow fiber membrane to produce hydrogen and ethylene.19 An H2 production rate of around 1.0 mL cm−2 min−1 was achieved in the core side of BCFZ hollow fiber with C2H4 yield around 53% in the shell side at 800◦C without extra catalyst addition. Li et al. made a breakthrough for coproduced ammo- nia synthesis gas and liquid-fuel synthesis gas in the membrane reactor (Ba0.98Ce0.05Fe0.95O3−δ) with Ru-based catalyst (1 wt% Ru/Ce0.85Sm0.15O2−δ), integrating nine conventional steps into one unit.20 The energy consump- tion for producing two types of synthesis gases can be reduced by 63% via this innovated membrane reactor. It is worthy to note that commercializing these interesting membrane concepts requires robust membranes to with- stand the reacting conditions. Creating novel membrane materials with long-term chemical and thermal stabili- ties and developing a highly efficient catalyst are highly needed. 2.2 Thermal decomposition of carbon dioxide by coupling with an oxidative process CO2 thermal decomposition is highly endothermic, occur- ring only at high temperature and limited by the thermo- dynamic equilibrium. Similar to water decomposition, this reaction can be coupled with an oxidative process to boost the CO2 conversion using MIEC membrane reactors. In this process, CO2 can be fed to one side of the membrane, and the produced O2 is extracted to other membrane side to provide oxygen source for oxidative processes. Fan et al. investigated the CO2 decomposition cou- pled with POM in SrCo0.5FeOx disk membrane (thickness: 1 mm) reactor without loading extra catalyst,21 and CO2 conversion of 10% was achieved at 940◦C. Later, more promising results were reported by Jin’s group at 900◦C using an SrCo0.4Fe0.5Zr0.1O3−δ disk membrane (thickness: 1.5 mm) reactor packed with Ni/Al2O3 catalyst for POM.22 The CO2 conversion, CH4 conversion, CO selectivity, and H2/CO ratio are 11.1%, 84.5%, 93%, and 1.8, respectively. The low CO2 conversion was caused not only by the limited thermodynamic equilibrium but also the kinetic barrier. Realizing this bottleneck, Jin et al. further improved the process by incorporating the catalysts for both reactions in the similar SrCo0.4Fe0.5Zr0.1O3−δ membrane reactor packedwith a perovskite oxide supported noblemetal cata- lyst (Pt/SrCo0.4Fe0.5Zr0.1O3−δ) for CO2 decomposition and Ni/Al2O3 for POM.23 At 900◦C, the achieved CO2 con- version and selectivity were 15.8% and 100%, respectively. However, it was surprising to see that the improved kinet- ics on CO2 conversion did not enhance the POM reactions in the other membrane side. Zhang et al. applied a dense Al2O3-doped SrCo0.4Fe0.5Zr0.1O3−δ tubular membrane (with Ni/Al2O3 catalyst) for coupling the POM reaction with CO2 decomposition.24 The CO2 conversion reached approx- imately 12.4% at 900◦C, whereas the CO selectivity and CH4 conversion were 93% and 86%, respectively. It is also worth noting that the CO2 conversion in the tubular membrane is higher than that of using disk-shape mem- brane at the same reaction temperature, which is mainly resulting from the increasing the oxygen permeation rate by reducing membrane thickness. Recently, Liang et al. demonstrated the simultaneous decomposition of water and carbon dioxide coupled with POM reaction in a dual- phase Ce0.9Pr0.1O2−δ–Pr0.6Sr0.4FeO3−δ disk membrane reactor (thickness: 0.6 mm).25 At 930◦C, synthesis gas pro- duction rates achieved on the H2O/CO2 feed and methane sweep sides are 1.3 and 3.9 mL cm−2 min−1, respectively. In contrast to typical thermochemical decomposition, effective CO2 and WS were accomplished at lower tem- peratures, which was attributed to the in situ rapid removal of the produced oxygen through the dual-phase membranes. Their work proposes a novel perspective and an alternate approach to transform water and CO2 into synthesis gas by combining solar energy, OTM reactor, and catalytic thermolysis. To improve the CO2 conversion, coupling of CO2 decomposition with POM has also been demonstrated in a porous–dense–porous triple-layered composite membrane reactor.26 It is interesting that this designed membrane reactor can be operating for over 500 h without any decrease of reaction performance. This design is an excellent candidate for combining the membrane reactor stability with high oxygen separation capability for potential industrial applications. 2.3 Decomposition of NOx by coupling with an oxidative process By coupling with an oxidative reaction, thermal degrada- tion of environment-polluting nitrogen oxides (NOx, i.e., NO, NO2, and N2O) to N2 and O2 can also be accom- plished in oxygen permeable dual-functional membrane reactors as shown in Figure 1. In contrast to the traditional direct catalytic decomposition procedure,27 the negative restriction of the produced oxygen on NOx conversion can be prevented by in situ removal of the surface oxygen employing the dual-functional membrane reactor. Caro’s group had demonstrated this new concept employing a BaCoxFeyZr1−x−yO3−δ hollow fiber membrane coupled with POM for the first time and their results revealed that NO orN2O conversion can reach almost 100% at 875◦C.28,29 The rapid consumption of permeated surface oxygen through using CH4 results in a larger gradient of oxygen 1494 CHEN et al. partial pressure, allowing NOx decomposition to continue. On the other side of the membrane, 90% selectivity of CO and 90% of methane conversion were obtained simultane- ously. In their later work, coupling of N2O decomposition with CO2 reforming of CH4 has been successfully demon- strated in a cobalt-free perovskite BaFe0.9Zr0.05Al0.05O3−δ (BFZ-Al) membrane reactor.30 Due to efficient in situ removal of the surface oxygen across the BFZ-Al mem- brane, almost 100% N2O conversion was obtained with 94% selectivity of CO and 97% of methane conversion at 900◦C on the other side of the membrane. It is also worth noting that even after 100 h of operation, no noticeable decrease in selectivity and activity was discovered, illus- trating the outstanding performance of their developed BFZ-Al membrane reactor. Recently, a novel dual-functional catalytic membrane reactor was developed for simultaneous POM and NO decomposition, where a BaBi0.05Co0.8Nb0.15O3−δ (BBCN) hollow fiber membrane integrated with Ni-phyllosilicate hollow sphere catalysts was employed.31 In comparison to previous reported studies,28,29 the operating tempera- ture required for attaining 100% NO conversion with this dual-functional catalytic membrane reactor was dramat- ically reduced to 675◦C. This excellent performance is primarily attributed to the very high catalytic activity of the employed catalysts and high oxygen permeability of the developed BBCNhollow fibermembrane. Significantly reducing the operating temperature is critical for lower- ing capital costs and energy consumption to improve the dual-functional membrane reactor’s energy efficiency. Similar to CO2 and water decomposition as discussed above, it should be also possible to couple NOx decomposi- tion with other oxidative processes like ethanol oxidative steam reforming and OCM to simultaneously maximize the reaction efficiency in both sides of the oxygen trans- port dual-functional membrane reactors, which has not reported in the literature. 3 OPPORTUNITIES AND FUTURE RESEARCH DIRECTIONS Despite the considerable advancements in the field of dual- functional membrane reactors as summarized in Table 1, there remain several hurdles that must be overcome before ceramic OTM reactors can be utilized in industrial applications for pollution control and chemical upgrad- ing. To expedite the commercialization of dense ceramic membrane reactors, forthcoming research endeavors con- cerning new material development, economic feasibility, long-term stability, and fundamental understanding could concentrate on the following four aspects. 3.1 Oxygen transport membrane material development The development of suitable membrane materials is of utmost importance for the successful implementation of dual-functional membrane reactors, which are inherently complex due to their integration of multiple processes and different materials, such as membranes and cata- lysts, into a single unit. Given that the membrane material serves as the core of these reactors, it is essential to prioritize the development of such materials to ensure optimal performance and stability. The development of oxygen permeable membrane materials for various appli- cations requires different specifications. Specifically, CO2- resistant alkaline earth-metal-free membranes, such as dual-phase or K2NiF4-type (Ruddlesden–Popper phase) membranes, are recommended if a CO2-rich feed or sweep gas was involved.2,35–40 Coating the membrane surfaces with a CO2-resistant layer is an effective approach to enhance CO2 resistance of the membranes with high oxygen permeation fluxes such as Sr- or Ba-containing single-phase perovskite-type OTMs.2,35,41 An ideal protec- tive layer material requires good ionic conductivity, high chemical and mechanical stability in CO2 atmosphere at high temperature, and good compatibility with the pro- tected membrane. However, there is a trade-off between the stability (chemical resistance) and the oxygen per- meability. Complete substitution of alkaline-earth cations Sr or Ba by rare-earth cations and reduction of cobalt content in single-phase perovskite-type membranes can effectively improve CO2 resistance2,35,42,43 but generally reduce the oxygen permeation flux. Table 2 shows the per- formance comparison of various OTMs recently reported in literature, which can be potential new materials for dual-functional membrane reactors. When the membrane reactor was used in reducing atmospheres, such as POM for syngas production, the membrane materials need to be stable in the presence of H2, CO, and CH4. Cobalt-rich perovskite membranes are unsuitable for this application due to their instability in reducing atmospheres, making cobalt-less or cobalt- free perovskite membranes or dual-phase membranes more favorable. Additionally, increasing the oxygen per- meation flux through the membrane is crucial, especially at low temperatures (T < 600◦C), to satisfy important catalytic reactions that operate at lower temperatures. The development of submicron membranes with modi- fied surface chemistry and/or microstructures can signifi- cantly improve oxygen permeation flux by altering surface exchange kinetics.1,2,7,35,44 The dual-functional membranes require high stability as the membranes are exposed to two different reaction CHEN et al. 1495 T A B L E 1 Su m m ar y of pe rf or m an ce an d pr oc es sp ar am et er so fc ou pl in g of tw o ch em ic al re ac tio ns th ro ug h an ox yg en tr an sp or tm em br an e (O TM )r ea ct or . R ea ct io n M em br an e co m po si ti on R ea ct or co nf ig ur at io n T (◦ C ) C at al ys t Pe rf or m an ce St ab ili ty (h ) R ef er en ce W S co up lin g w ith PO M La 0. 8C a 0 .2 Fe 0. 94 O 3− δ– A g H ol lo w fib er (w al l th ic kn es s: 0. 25 m m ) 95 0 N i/ La N iO 3/ γ- A l 2 O 3 (P O M re ac tio n si de ) r H 2 = 7. 9 m L cm − 2 m in − 1 ; X( C H 4) = 58 % ; S( CO )= 89 % 20 32 W S co up lin g w ith D RM Ba M g 0 .1 Zr 0. 05 Ti 0. 85 O 3− δ D is k (th ic kn es s: 0. 7 m m ) 99 0 N i-b as ed ca ta ly st (S üd -C he m ie A G ) (D RM re ac tio n si de ) r H 2 = 0. 8 m L cm − 2 m in − 1 ; X( C H 4) = 25 % ; S( CO )= 98 % 10 0 33 D ec om po si tio n of H 2O an d CO 2 co up lin g w ith PO M C e 0 .9 Pr 0. 1O 2− δ– Pr 0. 6S r 0 .4 Fe O 3− δ D is k (th ic kn es s: 0. 6 m m ) 93 0 N i/ A l 2 O 3 (P O M re ac tio n si de ) r H 2 = 0. 6 m L cm − 2 m in − 1 ; S( CO )= 98 % 10 0 25 D ec om po si tio n of CO 2 co up lin g w ith PO M La 0. 8C a 0 .2 Fe O 3− δ– C e 0 .9 G d 0 .1 O 2− δ D is k (th ic kn es s: 0. 11 m m ) 90 0 N iO –C e 0 .9 G d 0 .1 O 2− δ– La 0. 3S r 0 .7 Ti O 3− δ (P O M re ac tio n si de ); La 0. 8C a 0 .2 Fe O 3− δ– C e 0 .9 G d 0 .1 O 2− δ (C O 2 de co m po si tio n re ac tio n si de ) X( CO 2) = 40 % ; X( C H 4) = 80 % ; S( CO )= 10 0% 10 0 34 D ec om po si tio n of CO 2 co up lin g w ith PO M A l 2O 3- do pe d Sr C o 0 .4 Fe 0. 5Z r 0 .1 O 3− δ Tu be (th ic kn es s: 0. 45 m m ) 90 0 N i/ A l 2 O 3 (P O M re ac tio n si de ) X( CO 2) = 12 .4 % ; X( C H 4) = 86 % ; S( CO )= 93 % ; H 2/ CO = 1.8 – 24 D ec om po si tio n of N xO co up lin g w ith PO M Ba Fe 0. 9Z r 0 .0 5A l 0. 05 O 3− δ D is k (th ic kn es s: 1m m ) 90 0 – X( C H 4) = 97 % ; X( N 2O )= 10 0% ; S( CO )= 94 % 10 0 30 D ec om po si tio n of N O co up lin g w ith PO M Ba Bi 0. 05 C o 0 .8 N b 0 .15 O 3− δ H ol lo w fib er (w al l th ic kn es s: 0. 2 m m ) 75 0 N i-p hy llo si lic at e ho llo w sp he re (P O M re ac tio n si de ) X( C H 4) = 95 % ; X( N O )= 10 0% ; S( CO )= 94 % – 31 D ec om po si tio n of N 2O co up lin g w ith O D E Ba C o x Fe yZ r 1− x− yO 3− δ H ol lo w fib er (w al l th ic kn es s: 0. 17 m m ) 85 0 N i/ A l 2 O 3 (O D E re ac tio n si de ) X( C 2H 6) = 85 % ; S( C 2H 4) = 86 % ; X( N 2O )= 10 0% – 12 N ot e: Th e st ab ili ty (h )v al ue re pr es en ts th e m ax im um du ra tio n of th e m ea su re m en ts co nd uc te d in th e re sp ec tiv e st ud ie sc ite d w ith ou tb re ak do w n; T: te m pe ra tu re (◦ C ). A bb re vi at io ns :D RM ,d ry re fo rm in g of m et ha ne ;O D E, ox id at iv e de hy dr og en at io n of et ha ne ;P O M ,p ar tia lo xi da tio n of m et ha ne ;S ,s el ec tiv ity ;W S, w at er sp lit tin g; X, co nv er si on . 1496 CHEN et al. T A B L E 2 A n ov er vi ew of th e ox yg en pe rm ea tio n flu x da ta fr om se ve ra lp ot en tia lo xy ge n tr an sp or tm em br an es (O TM s) re ce nt ly re po rt ed in lit er at ur e. M em br an e co m po si ti on C on fi gu ra ti on s d (m m ) J( O 2) a (m L cm − 2 m in − 1 ) J( O 2) b (m L cm − 2 m in − 1 ) T (◦ C ) J( O 2) b st ab ili ty (h ) R ef er en ce 30 w t% La 0. 15 Sr 0. 85 Fe O 3− δ– 70 w t% La 0. 15 C e 0 .8 C u 0 .0 5O 2− δ D is k 0. 6 0. 45 0. 27 90 0 10 0 45 60 w t% C e 0 .9 N d 0 .1 O 2− δ– 40 w t% N d 0 .6 Sr 0. 4C oO 3− δ D is k 0. 6 0. 65 0. 55 95 0 15 0 46 40 w t% C e 0 .9 Pr 0. 1O 2− δ– 60 w t% N d0 0. 5S r 0 .5 Fe 0. 9C u 0 .1 O 3− δ D is k 0. 6 0. 97 0. 32 12 23 70 47 60 w t% C e 0 .8 Sm 0. 2O 2− δ– 40 w t% Sm 0. 3S r 0 .7 C u 0 .2 Fe 0. 8O 3− δ D is k 0. 6 0. 84 0. 7 95 0 40 0 48 25 w t% Sm 0. 2C e 0 .8 O 1.9 25 –7 5 w t% Sr C o 0 .4 Fe 0. 55 Zr 0. 05 O 3− δ (S D C –S C FZ ) D is k 0. 6 1.2 6 – 95 0 72 49 75 w t% C e 0 .8 5S m 0. 15 O 1.9 25 –2 5 w t% Sm 0. 6S r 0 .4 A l 0. 3F e 0 .7 O 3− δ H ol lo w fib er ∼ 0. 32 1.0 3 0. 91 5 95 0 56 50 La 2N i 0. 95 M o 0 .0 5O 4+ δ H ol lo w fib er – 2. 88 2. 75 95 0 18 5 51 La 0. 6S r 0 .4 C o 0 .2 Fe 0. 8O 3− δ Si x- ch an ne l ho llo w fib er 0. 05 2 1.8 7 – 95 0 – 52 La 0. 6S r 0 .4 C o 0 .2 Fe 0. 8O 3− δ– (L a 0 .5 Sr 0. 5) 2C oO 4+ δ H ol lo w fib er – 3. 2 2. 6 90 0 10 0 53 La 2N i 0. 95 M o 0 .0 5O 4+ δ H ol lo w fib er – 2. 88 2. 75 95 0 18 5 51 Ba 0. 5S r 0 .5 C o 0 .8 Fe 0. 2O 3− δ 19 -c ha nn el ho llo w fib er – 8. 85 – 90 0 – 54 N ot e: d is th e m em br an e th ic kn es s( m m ). a O xy ge n pe rm ea tio n flu x un de ra ir/ H e or ai r/ A rg ra di en t. b O xy ge n pe rm ea tio n flu x un de ra ir/ CO 2 gr ad ie nt .T he st ab ili ty (h )v al ue re pr es en ts th e m ax im um du ra tio n of th e m ea su re m en ts co nd uc te d in th e re sp ec tiv e st ud ie sc ite d w ith ou tb re ak do w n. T: te m pe ra tu re (◦ C ). CHEN et al. 1497 conditions, in most cases, to withstand the erosion of reducing gases (i.e., hydrogen or methane) and acidic gases (i.e., CO2) at high temperatures. The mixed ionic- electronic conducting membranes with such high chem- ical resistance in single phase are rarely reported; thus, dual-phase membranes may have their niche for such applications. The oxygen ionic conducting phase and electronic phase can be individually chosen from these robust components like a fluorite-type conductor (yttria- stabilized zirconia, Sm-doped ceria (SDC), or Gd-doped ceria). In particular, a novel design consisting of a robust ion conductor with an external metal coating as the short circuit was put forward to enhance the CO2 and H2 resistance.55,56 These new designs may have potentials for dual-functional membrane reactors, despite that no literature has been reported. 3.2 Engineering of the membrane Enhancing the performance of membrane reactors through engineering of the membranes can be achieved by various strategies. One of the effective strategies is to modify the membrane configurations by preparing an asymmetric or hollow fiber membrane, which reduces the membrane thickness and decreases oxygen ion diffusion resistance.2,35,57 Membrane reactors generally require to load an extra catalyst. Thus, catalyst development for membrane reactors is crucial to enhance performance. However, limited research has been conducted in this area. Most catalysts are supported by alumina, silica, or zeolites with limited oxygen ionic conductivities, which can react with membrane materials at high temperatures, thereby reducing the membrane’s oxygen permeability.2 To address this issue, in situ precipitating of nanoparti- cle catalysts in membrane materials is a more suitable approach formembrane reactors, as it can provide catalytic activities for reactions and weaken the negative effects of the reaction between the membrane and the catalyst. Recently, Jin et al.58 demonstrated an “in situ growth” strategy to design homologous perovskite catalysts applied within a perovskite membrane reactor for the POM as shown in Figure 2. FeNi (FeNi3) bimetallic nanoparticles exsolved from Sr0.9(Fe0.81Ta0.09Ni0.1)O3−δ (STFN) parent oxide to form the FeNi/STFN exsolution-based catalyst, which was used to construct a catalytic membrane reac- tor based on a Ba0.5Co0.5Fe0.22Nb0.08O3−δ hollow fiber membrane (four-channel). The performance of the cat- alytic membrane reactor was dramatically improved with FeNi/SFTN0.9 over the fresh STFN catalyst, demonstrat- ing the advantages of using an exsolution-based perovskite catalyst and effectively suppressing its excessive exsolu- tion/dissolution. The CH4 conversion, CO selectivity, H2 selectivity, and H2/CO ratio were 98%, 97%, 98%, and 2.2, respectively. This study provides valuable insights into the development of customized catalysts for dual-functional membrane reactors. In addition to the development of efficient catalysts, understanding the influence of different catalyst loading methods on membrane reactor performance is crucial for efficiently integrating the catalyst within the reactor. To this end, the working principles for four types of catalyst contactmodes (I–IV), as illustrated in Figure 2, can provide a simple guideline for designingmembrane reactors for dif- ferent oxidative reactions. For theOCMreaction,mode-III, where the catalysts possess ion conducting properties and are intimately contactedwith themembrane, is considered the best situation. In this mode, the triple-phase-boundary (TPB) area is significantly expanded to the whole exposed particle surface. The entire membrane surface may act as a catalyst, allowing the utilization of ionized oxygen only without gas-phase oxygen if the reaction and permeation rates are well-controlled and matched. However, for some oxidations, such as those that do not benefit from catalysts of mode-III, a better design is mode-IV, which combines modes-II and -III by integrating normal catalyst andmem- brane material particles together to promote the reaction by expanding the TPB area. Inmode-I,mainly gaseous oxy- gen reaches the catalyst surface to participate in reactions, but for POM, the oxygen partial pressure at the membrane interface facing the catalyst can protect the membrane in a strongly reducing atmosphere. To achieve better per- formance, the design must take into account the specific reaction mechanism requiring either controlled gaseous oxygen or lattice oxygen. Understanding the fundamentals of catalyst contact mode and their combination will aid in improving membrane reactor performance. A more com- prehensive discussion of catalyst contact mode and their combination can be found in Refs. [2, 59]. Incorporating catalysts in membrane reactors while ensuring their retention on the membrane surface is a critical concern as loosely attached catalysts are prone to detachment under high-temperature fluid flow or by aggregation driven by a reduction in surface free energy. Recently, Han and Liu et al.60 demonstrated the devel- opment of a wrinkled outer surface morphology for La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) hollow fiber membrane, as depicted in Figure 2c, which represents a novel strategy for catalytic carrier design. The Ag-coated wrinkled LSCF membrane exhibited an O2 flux of 1.27 mL cm−2 min−1 at 900◦C, which was two times higher than that of the conventional membrane with Ag-coating under the same conditions. This study presents a valuable approach toward membrane engineering for anchoring catalysts in membrane reactors. Ideally, the honeycomb structure’s microchannels should be located on the outer surface, 1498 CHEN et al. F IGURE 2 (a) Schematic diagrams of a new catalytic membrane reactor with exsolution-based catalysts designed by a “in situ growth” strategy. (b) Reaction pathways and oxygen permeation for oxidative reactions by oxygen transport membranes (OTMs) with various catalyst contact modes. (c) A schematic representation of the different cross-sectional microstructures of hollow fiber membranes. (d) Scanning electron microscope [SEM] images of the SFN/SCN dual-layered hollow fiber: (i) cross section; (ii) zoomed-in area marked on (i); (iii) outer porous surface; (iv) inner dense surface. Source: (a) Reprinted with permission from Ref. [58]. Copyright 2020 Elsevier; (b) reprinted with permission from Ref. [2]. Copyright 2022 John Wiley and Sons; (c) reprinted with permission from Ref. [60]. Copyright 2021 Elsevier; (d) reprinted with permission from Ref. [65]. Copyright 2023 Elsevier. as illustrated in Figure 2c. However, creating externally open pores is challenging without the inclusion of an extra acid etching step.61 In this regard, engineering a membrane that offers highmechanical strength and excel- lent oxygen permeability is crucial for practical industrial applications, which is highly needed to be explored in future. The enhancement of mechanical strength in hol- low fibers can be achieved by increasing their cross- sectional area through a multichannel configuration.62–65 This design can provide a larger permeation area and higher membrane-packing density within a given volume. Notably, multichannel hollow fibers utilizing perovskite oxides were first developed by Jin’s group for efficient pro- duction of pure oxygen.62 These multichannel fibers have demonstrated significant improvements in both mechan- ical strength and oxygen permeation flux compared to a single-channel hollow fiber membrane.63,66 Similar results have been reported in Li’s group via investigating three-, four-, seven-channel, and bio-inspired six-channel La0.6Sr0.4Co0.2Fe0.8O3−δ hollow fibers.52,67 Additionally, a recent advancement in the field includes the develop- ment of SrFe0.8Nb0.2O3−δ (SFN)/SrCo0.9Nb0.1O3−δ (SCN) dual-layered seven-channel hollow fiber membranes, fab- ricated through a co-spinning process and one-step ther- mal processing (see Figure 2d).65 These dual-layered seven-channel hollow fiber membranes exhibit superior mechanical strength and high oxygen permeability, with the porous SFN outer layer effectively preventing perfor- mance degradation under a CO2-containing sweep gas in comparison to SCN membranes. Moreover, the SFN/SCN dual-layeredmembranes exhibit a stable operation for over 200 h in the 20% CO2–80% He sweep gas, maintaining the high oxygen permeation flux.65 The advantageous prop- erties of multichannel hollow fiber membranes, includ- ing enhanced mechanical strength, permeation flux, and CHEN et al. 1499 F IGURE 3 (a) Plasma assisted hollow fiber membrane system for CO2 decomposition and gas separation. (b) A novel dielectric barrier discharge plasma (DBD)-membrane design for efficient oxygen permeation. (c) A schematic representation of the solar-driven thermochemical CO2 splitting across a CeO2 membrane reactor. (d) The configurations of CO2/O2 cotransport membrane reactor for oxidative coupling of methane (OCM). Source: (a) Reprinted with permission from Ref. [68]. Copyright 2020 Elsevier; (b) reprinted with permission from Ref. [74]. Copyright 2022 Elsevier; (c) reprinted with permission from Ref. [75]. Copyright 2017 Elsevier; (d) reprinted with permission from Ref. [78]. Copyright 2022 Elsevier. packing density, establish them as reliable and economi- cally viable options. Consequently, these membranes rep- resent a significant advancement and a promising future direction in membrane technology, holding potential for scalability and broader applications. 3.3 Innovation in the OTM reactors Recently, there have been proposals for innovation concepts on the OTM reactor, which could serve as a promising strategy for future research to enhance the per- formance of dual-functional membrane reactors. Among the emerging technologies for CO2 conversion, plasma- based approaches have gained considerable interest due to their flexibility and efficiency.68–70 Chen et al.71 first pro- posed a plasma-assisted La0.6Ca0.4Co0.5Fe0.5O3−δ (LCCF) hollow fiber membrane concept that simultaneously improved gas separation and CO2 conversion as depicted in Figure 3a. The oxygen permeation flux was significantly enhanced by almost a factor of 3 in aCO2 plasma compared to the same LCCF hollow fiber membrane studied under conventional conditions. This improvementwas attributed to the unique atmosphere in the CO2 plasma, which com- prises excited species, electrons, radicals, photons, molecules, and ions. The constant high oxygen perme- ation flux was maintained during long-term operation, which is of particular importance for commercial applica- tion. Furthermore, the rapid switching between operation and stand-by demonstrated the additional strength of the developed system to cope with potential unstable energy supply when using renewable energies. Buck et al.72,73 have conducted further improvements based on this concept, and Zheng et al.74 confirmed the benefit of the unique atmosphere provided by plasma to enhance oxygen permeability. They proposed a novel dielectric barrier discharge plasma–membrane design for efficient oxygen permeation at low temperatures (Figure 3b). At 600◦C with a plasma power of 15 W, the oxygen permeation flux of the La0.6 Sr0.4Co0.2Fe0.8O3−δ membrane (disk) increased remarkably by almost 30 times. These newly developed plasma-membrane reactor designs hold partic- ular promise for improving the performance of membrane reactors, especially for important catalytic reactions that operate at lower temperatures, such as OCM. In recent years, there has been significant progress in solar capture and storage technologies, and integrat- ing solar-driven processes into membrane reactors offers a promising approach to convert solar energy into dif- ferent forms of energy.2,75,76 Tou et al.75 conducted an experimental study on the continuous CO2 splitting under steady-state isothermal/isobaric conditions in a CeO2 1500 CHEN et al. membrane reactor driven by concentrated radiation for the first time (see Figure 3c). A similar concept has also been investigated by Abanades et al.,76 focusing on the design and development of a new membrane solar reac- tor for continuous CO2 splitting. Tou et al. also tested the feasibility of splitting both H2O and CO2 in a tubular CeO2 membrane reactor heated by simulated concentrated solar radiation into separate streams of oxygen and syn- gas, respectively.77 This simple solar membrane reactor technology demonstrates its potential for co-splitting CO2 and H2O to fuels under high flux conditions. However, heat and mass transfer were impractically slow, restricting the reaction rates. Moreover, these solar-driven processes have not yet been investigated or demonstrated as dual- functional membrane reactors, representing a promising research direction to enhance overall efficiency. A recent study by Huang et al.78 has proposed an intriguing CO2/O2 cotransport membrane reactor for the OCM conversion, as depicted in Figure 3d. Their results demonstrate that the co-captured CO2/O2 mixture con- verts methane into C2H6 in the presence of a catalyst (2% Mn–5% Na2WO4/SiO2). Then C2H6 was thermally cracked into H2 and C2H4. The presence of CO2 leads to a reduc- tion in the local partial pressure of O2, resulting in a higher C2 selectivity by reducing the propensity of C2-products reoxidation. These innovative concepts may provide a new avenue for designing suitable CO2/O2 cotransport membrane materials for dual-functional membrane reactors. However, it should be noted that all the abovementioned innovative concepts are still in the early stages of devel- opment, and significant advancements are necessary in the future to improve the efficiency and economics of the process before industrial implementation can be realized. 3.4 Reaction mechanisms in the dual-functional membrane reactors Comprehending the relationship between the reconstruc- tion of membranes and catalysts and their activation or deactivation in membrane reactors is crucial to achieve the rational design of high-performancematerials that can withstand harsh operating conditions for a long-term oper- ation. Significant progress has been made by the scientific community to improve the understanding of the oxygen transport mechanism.35,57,79 Spectroscopic techniques have been employed to investigate the degradation pro- cesses that occur duringmembrane exposure to CO2,35 but these investigations have not been conducted during the actual application process. In situ characterization analysis has not been carried out formembrane reactors that couple two reactions as well so far. Advanced scientific research methods, such as in situ Fourier-transform infrared spectroscopy being particularly useful for monitoring the creation of the intermediates,80,81 are highly recom- mended to investigate the reaction mechanism during the actual reaction processes in dual-functional membrane reactors. The morphological change can be evaluated using in situ transmission electron microscopy, whereas in situ X-ray powder diffraction can provide information on the crystalline structure for a long-term operation. Computational simulations andmodeling have emerged as indispensable tools for advancing the field of membrane reactors. The progress in developing oxygen permeation models has led to the introduction of more sophisti- cated models that incorporate bulk diffusion and surface exchange reactions, resulting in more accurate predictions of oxygen permeation fluxes. Existing models for oxy- gen permeation flux include the Wagner, Bouwmeester, Xu–Thomson, Li, Tan and Li, Ghadimi, Kim, Zhu, Van Hassel, and Dimitrakopoulos and Ghoniem models, each based on specific transport mechanisms and underly- ing assumptions.2,82 The application prospects of these oxygen permeation models extend beyond their use in membrane reactors, encompassing other reaction-based applications and more extensive modeling studies, such as computational fluid dynamics (CFD).2,83 For instance, Feng et al. developed a 3D CFD model to investigate the behavior of perovskite hollow fiber membrane modules (La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF)) for oxygen separation.84 Similarly, Sommer et al. explored CFD and continuously stirred tank reactor (CSTR) models to enhance the yield of partial oxidation products in mixed ionic electronic mem- brane reactors utilizing an LSCF disk membrane reactor for OCM.85 Their studies shed light on the selectivity of carbon products for different reactor configurations and compared the results of theCFDmodelwith a less complex two-chamberCSTRmodel. Themodeling tools can be used to identify optimal operating conditions and the results demonstrated the importance of gas phase chemistry and flow configuration. It is crucial to note that incorporat- ing oxygen permeation models into reactive membrane technology necessitates additional considerations, such as the impact of pressure drop from combustion and its effects on the driving force of oxygen partial pressure or membrane permeability. Furthermore, the catalytic nature of MIECs should be taken into account to enhance the product yield in future studies.85 The continuous develop- ment of computational simulations and modeling is vital for supporting the rapid progress in experimental-based membrane materials and technology, particularly in sim- ulating the complex behavior of oxygen permeation in dual-functional membrane reactors.2,82,86 Nevertheless, there remains a gap in understanding both the stability control of chemical reactions and their CHEN et al. 1501 influence on membrane performance. CFD can be a promising approach to investigate local heat transfer behavior, which directly influences the chemical reactions within amembrane reactor. Investigating these fundamen- tal issues will undoubtedly provide valuable insights into the development of next-generation membrane materials and catalysts. 4 CONCLUSIONS The utilization of oxygen transport dual-functional mem- brane reactors for coupling various reactions provides numerous opportunities for energy conversion and stor- age. Despite recent advancements, the successful applica- tion of these oxygen transport dual-functional membrane reactors on a large industrial scale requires overcoming research and technological challenges. The integration of these membrane materials into engineering concepts and devices has been discussed, and innovative concepts offer significant potentials to improve energy efficiency and identify new possibilities for future commercial appli- cations. The development of more robust membranes capable of withstanding the respective reacting condi- tions on each side of the membrane reactor is crucial. Thus, interdisciplinary approaches must be used to attain the optimal balance between performance and stability for high-performance membrane reactors that promote energy-efficient and sustainable chemistry. As such, more joint efforts from multidisciplinary teams are needed to tackle these challenges. ACKNOWLEDGMENTS M.W. and A.W. kindly thank the Federal Ministry of Education and Research for financial support during the NexPlas (grant number: 03SF0618B) and PiCK project (grant number: 03SFK2S3B). G.C., G.H., and A.W. kindly thank the Hydrogen performance center in Hesse for financial support during the Green materials for Green H2 project. Open access funding enabled and organized by Projekt DEAL. CONFL ICT OF INTEREST STATEMENT All the authors declare no conflicts of interest. ORCID GuoxingChen https://orcid.org/0000-0002-1570-4639 REFERENCES 1. Zhu X, Yang W. Microstructural and interfacial designs of oxygen-permeable membranes for oxygen separation and reaction–separation coupling. Adv Mater. 2019;31(50):1902547. https://doi.org/10.1002/ADMA.201902547 2. Chen G, Feldhoff A, Weidenkaff A, Li C, Liu S, Zhu X, et al. Roadmap for sustainable mixed ionic-electronic conducting membranes. Adv Funct Mater. 2022;32(6):2105702. https://doi. org/10.1002/ADFM.202105702 3. Basile A, editor. Handbook of membrane reactors. Sawston: Woodhead Publishing; 2013. https://www.sciencedirect.com/ book/9780857094155/handbook-of-membrane-reactors#book- description 4. Kwon Y-I, Nam GD, Lee G, Choi S, Joo JH. Recent progress and challenges inmixed ionic–electronic conductingmembranes for oxygen separation. Adv Energy Sustain Res. 2022;3(11):2200086. https://doi.org/10.1002/AESR.202200086 5. Kiebach R, Pirou S, Martinez Aguilera L, Haugen AB, Kaiser A, Hendriksen PV, et al. A review on dual-phase oxygen transport membranes: from fundamentals to commercial deployment. J Mater Chem A. 2022;10(5):2152–95. https://doi.org/10.1039/ D1TA07898D 6. Sunarso J, Hashim SS, ZhuNa, ZhouW. Perovskite oxides appli- cations in high temperature oxygen separation, solid oxide fuel cell and membrane reactor: a review. Prog Energy Combust Sci. 2017;61:57–77. https://doi.org/10.1016/J.PECS.2017.03.003 7. Wei Y, Yang W, Caro J, Wang H. Dense ceramic oxygen per- meable membranes and catalytic membrane reactors. Chem Eng J. 2013;220:185–203. https://doi.org/10.1016/J.CEJ.2013. 01.048 8. Deibert W, Ivanova ME, Baumann S, Guillon O, Meulenberg WA. Ion-conducting ceramic membrane reactors for high- temperature applications. J Membr Sci. 2017;543:79–97. https:// doi.org/10.1016/j.memsci.2017.08.016 9. Arratibel Plazaola A, Cruellas Labella A, Liu Y, Badiola Porras N, Pacheco Tanaka D, Sint Annaland M, et al. Mixed ionic- electronic conducting membranes (MIEC) for their applica- tion in membrane reactors: a review. Processes. 2019;7(3):128. https://doi.org/10.3390/PR7030128 10. Garcia-Fayos J, Serra JM, Luiten-Olieman MWJ, Meulenberg WA.Gas separation ceramicmembranes. In: Advanced ceramics for energy conversion and storage. Amsterdam: Elsevier; 2020. p. 321–85. https://doi.org/10.1016/B978-0-08-102726-4.00008-9 11. Wu X-Yu, Ghoniem AF. Mixed ionic-electronic conducting (MIEC) membranes for thermochemical reduction of CO2: a review. Prog Energy Combust Sci. 2019;74:1–30. https://doi.org/ 10.1016/J.PECS.2019.04.003 12. Jiang H,Wang H, Liang F, Werth S, Schirrmeister S, Schiestel T, et al. Improved water dissociation and nitrous oxide decomposi- tion by in situ oxygen removal in perovskite catalytic membrane reactor. Catal Today. 2010;156(3–4):187–90. https://doi.org/10. 1016/j.cattod.2010.02.027 13. Jiang H, Wang H, Werth S, Schiestel T, Caro J. Simultaneous production of hydrogen and synthesis gas by combining water splitting with partial oxidation of methane in a hollow-fiber membrane reactor. Angew Chem Int Ed. 2008;47(48):9341–4. https://doi.org/10.1002/ANIE.200803899 14. Jia L, He G, Zhang Y, Caro J, Jiang H. Hydrogen purification through a highly stable dual-phase oxygen-permeable mem- brane. Angew Chem Int Ed. 2021;60(10):5204–8. https://doi.org/ 10.1002/ANIE.202010184 15. Jiang H, Liang F, Czuprat O, Efimov K, Feldhoff A, Schirrmeister S, et al. Hydrogen production by water dissoci- ation in surface-modified BaCoxFeyZr1−x−yO3−δ hollow-fiber membrane reactor with improved oxygen permeation. https://orcid.org/0000-0002-1570-4639 https://orcid.org/0000-0002-1570-4639 https://doi.org/10.1002/ADMA.201902547 https://doi.org/10.1002/ADFM.202105702 https://doi.org/10.1002/ADFM.202105702 https://www.sciencedirect.com/book/9780857094155/handbook-of-membrane-reactors#book-description https://www.sciencedirect.com/book/9780857094155/handbook-of-membrane-reactors#book-description https://www.sciencedirect.com/book/9780857094155/handbook-of-membrane-reactors#book-description https://doi.org/10.1002/AESR.202200086 https://doi.org/10.1039/D1TA07898D https://doi.org/10.1039/D1TA07898D https://doi.org/10.1016/J.PECS.2017.03.003 https://doi.org/10.1016/J.CEJ.2013.01.048 https://doi.org/10.1016/J.CEJ.2013.01.048 https://doi.org/10.1016/j.memsci.2017.08.016 https://doi.org/10.1016/j.memsci.2017.08.016 https://doi.org/10.3390/PR7030128 https://doi.org/10.1016/B978-0-08-102726-4.00008-9 https://doi.org/10.1016/J.PECS.2019.04.003 https://doi.org/10.1016/J.PECS.2019.04.003 https://doi.org/10.1016/j.cattod.2010.02.027 https://doi.org/10.1016/j.cattod.2010.02.027 https://doi.org/10.1002/ANIE.200803899 https://doi.org/10.1002/ANIE.202010184 https://doi.org/10.1002/ANIE.202010184 1502 CHEN et al. Chemistry: A Eur J. 2010;16(26):7898–903. https://doi.org/ 10.1002/CHEM.200902494 16. Fang W, Steinbach F, Cao Z, Zhu X, Feldhoff A. A highly efficient sandwich-like symmetrical dual-phase oxygen- transporting membrane reactor for hydrogen production by water splitting. Angew Chem Int Ed. 2016;55(30):8648–51. https://doi.org/10.1002/anie.201603528 17. Zhu Na, Dong X, Liu Z, Zhang G, Jin W, Xu N. Toward highly- effective and sustainable hydrogen production: bio-ethanol oxidative steam reforming coupled with water splitting in a thin tubular membrane reactor. Chem Commun. 2012;48(57):7137–9. https://doi.org/10.1039/C2CC30184A 18. Cao Z, Jiang H, Luo H, Baumann S, Meulenberg WA, Voss H, et al. Simultaneous overcome of the equilibrium limitations in BSCF oxygen-permeable membrane reactors: water splitting andmethane coupling. Catal Today. 2012;193(1):2–7. https://doi. org/10.1016/J.CATTOD.2011.12.018 19. Jiang H, Cao Z, Schirrmeister S, Schiestel T, Caro J. A coupling strategy to produce hydrogen and ethylene in a membrane reac- tor. Angew Chem Int Ed. 2010;49(33):5656–60. https://doi.org/ 10.1002/ANIE.201000664 20. Li W, Zhu X, Chen S, YangW. Integration of nine steps into one membrane reactor to produce synthesis gases for ammonia and liquid fuel. Angew Chem Int Ed. 2016;55(30):8566–70. https:// doi.org/10.1002/ANIE.201602207 21. Fan Y, Ren J-Y, Onstot W, Pasale J, Tsotsis TT, Egolfopoulos FN. Reactor and technical feasibility aspects of a CO2 decomposition-based power generation cycle, utilizing a high-temperature membrane reactor. Ind Eng Chem Res. 2003;42(12):2618–26. https://doi.org/10.1021/IE020980R 22. Jin W, Zhang C, Zhang P, Fan Y, Xu N. Thermal decomposi- tion of carbondioxide coupledwith POM in amembrane reactor. AIChE J. 2006;52(7):2545–50. https://doi.org/10.1002/AIC.10850 23. Jin W, Zhang C, Chang X, Fan Y, Xing W, Xu N. Efficient catalytic decomposition of CO2 to CO and O2 over Pd/mixed- conducting oxide catalyst in an oxygen-permeable membrane reactor. Environ Sci Technol. 2008;42(8):3064–8. https://doi.org/ 10.1021/ES702913F 24. Zhang C, Jin W, Yang C, Xu N. Decomposition of CO2 coupled with POM in a thin tubular oxygen-permeable membrane reac- tor. Catal Today. 2009;148(3–4):298–302. https://doi.org/10.1016/ j.cattod.2009.08.007 25. Liang W, Cao Z, He G, Caro J, Jiang H. Oxygen transport mem- brane for thermochemical conversion of water and carbon diox- ide into synthesis gas. ACS Sustain Chem Eng. 2017;5(10):8657– 62. https://doi.org/10.1021/ACSSUSCHEMENG.7B01305 26. Zhang K, Zhang G, Liu Z, Zhu J, Zhu Na, Jin W. Enhanced stability of membrane reactor for thermal decomposition of CO2 via porous-dense-porous triple-layer composite membrane. J Membr Sci. 2014;471:9–15. https://doi.org/10.1016/J.MEMSCI. 2014.06.060 27. Zhu J, Thomas A. Perovskite-type mixed oxides as catalytic material for NO removal. Appl Catal B Environ. 2009;92(3– 4):225–33. https://doi.org/10.1016/J.APCATB.2009.08.008 28. Jiang H, Wang H, Liang F, Werth S, Schiestel T, Caro J. Direct decomposition of nitrous oxide to nitrogen by in situ oxygen removalwith a perovskitemembrane.AngewChem Int EdEngl. 2009;48(16):2983–6. https://doi.org/10.1002/ANIE.200804582 29. Jiang H, Xing L, Czuprat O, Wang H, Schirrmeister S, Schiestel T, et al. Highly effective NO decomposition by in situ removal of inhibitor oxygen using an oxygen transporting membrane. Chem Commun. 2009;28(44):6738–40. https://doi.org/10.1039/ B912269A 30. Liang W, Megarajan SK, Liang F, Zhang Y, He G, Liu Z, et al. Coupling of N2O decomposition with CO2 reforming of CH4 in novel cobalt-free BaFe0.9Zr0.05Al0.05O3−δ oxygen transport membrane reactor. Chem Eng J. 2016;305:176–81. https://doi. org/10.1016/J.CEJ.2015.10.067 31. Wang Z, Li Z, Cui Y, Chen T, Hu J, Kawi S. Highly efficient NO decomposition via dual-functional catalytic perovskite hol- low fiber membrane reactor coupled with partial oxidation of methane at medium-low temperature. Environ Sci Technol. 2019;53(16):9937–46. https://doi.org/10.1021/ACS.EST.9B02530 32. Zhang S, Li T, Wang B, Zhou Z, Meng X, Yang N, et al. Cou- pling water splitting and partial oxidation of methane (POM) in Ag modified La0.8Ca0.2Fe0.94O3-δ hollow fiber membrane reactors for co-production of H2 and syngas. J Membr Sci. 2022;659:120772. https://doi.org/10.1016/J.MEMSCI.2022.120772 33. He G, Ling Y, Jiang H, Toghan A. Barium titanate as a highly stable oxygen permeable membrane reactor for hydrogen production from thermal water splitting. ACS Sus- tain Chem Eng. 2021;9(33):11147–54. https://doi.org/10.1021/ acssuschemeng.1c03118 34. Park JH, Kwon Y-Il, Nam GD, Joo JH. Simultaneous con- version of carbon dioxide and methane to syngas using an oxygen transport membrane in pure CO2 and CH4 atmospheres. J Mater Chem A. 2018;6(29):14246–54. https://doi.org/10.1039/ C8TA03021A 35. Zhang C, Sunarso J, Liu S. Designing CO2-resistant oxygen- selective mixed ionic-electronic conducting membranes: guide- lines, recent advances, and forward directions. Chem Soc Rev. 2017;46(10):2941–3005. https://doi.org/10.1039/c6cs00841k 36. Chen G, Widenmeyer M, Tang B, Kaeswurm L, Wang L, Feldhoff A, et al. A CO and CO2 tolerating (La0.9Ca0.1)2(Ni0.75Cu0.25)O4+δ Ruddlesden-Popper membrane for oxygen separation. Front Chem Sci Eng. 2019;14(3):405–14. https://doi.org/10.1007/S11705-019-1886-0 37. Chen G, Tang B, Widenmeyer M, Wang L, Feldhoff A, Weidenkaff A. Novel CO2-tolerant dual-phase Ce0.9Pr0.1O2–δ– La0.5Sr0.5Fe0.9Cu0.1O3–δ membranes with high oxygen perme- ability. J Membr Sci. 2020;595:117530. https://doi.org/10.1016/J. MEMSCI.2019.117530 38. Han N, Guo X, Cheng J, Liu P, Zhang S, Huang S, et al. Inhibit- ing in situ phase transition in Ruddlesden-Popper perovskite via tailoring bond hybridization and its application in oxygen permeation. Matter. 2021;4(5):1720–34. https://doi.org/10.1016/J. MATT.2021.02.019 39. Johanning M, Widenmeyer M, Escobar Cano G, Zeller V, Klemenz S, Chen G, et al. Recycling process development with integrated life cycle assessment—a case study on oxygen trans- port membrane material. Green Chem. 2023;25(12):4735–49. https://doi.org/10.1039/D3GC00391D 40. Chen G, Zhao Z, Widenmeyer M, Frömling T, Hellmann T, Yan R, et al. A comprehensive comparative study of CO2-resistance and oxygen permeability of 60 wt% Ce0.8M0.2O2–δ (M = La, Pr, Nd, Sm, Gd)–40 wt% La0.5Sr0.5Fe0.8Cu0.2O3–δ dual-phase https://doi.org/10.1002/CHEM.200902494 https://doi.org/10.1002/CHEM.200902494 https://doi.org/10.1002/anie.201603528 https://doi.org/10.1039/C2CC30184A https://doi.org/10.1016/J.CATTOD.2011.12.018 https://doi.org/10.1016/J.CATTOD.2011.12.018 https://doi.org/10.1002/ANIE.201000664 https://doi.org/10.1002/ANIE.201000664 https://doi.org/10.1002/ANIE.201602207 https://doi.org/10.1002/ANIE.201602207 https://doi.org/10.1021/IE020980R https://doi.org/10.1002/AIC.10850 https://doi.org/10.1021/ES702913F https://doi.org/10.1021/ES702913F https://doi.org/10.1016/j.cattod.2009.08.007 https://doi.org/10.1016/j.cattod.2009.08.007 https://doi.org/10.1021/ACSSUSCHEMENG.7B01305 https://doi.org/10.1016/J.MEMSCI.2014.06.060 https://doi.org/10.1016/J.MEMSCI.2014.06.060 https://doi.org/10.1016/J.APCATB.2009.08.008 https://doi.org/10.1002/ANIE.200804582 https://doi.org/10.1039/B912269A https://doi.org/10.1039/B912269A https://doi.org/10.1016/J.CEJ.2015.10.067 https://doi.org/10.1016/J.CEJ.2015.10.067 https://doi.org/10.1021/ACS.EST.9B02530 https://doi.org/10.1016/J.MEMSCI.2022.120772 https://doi.org/10.1021/acssuschemeng.1c03118 https://doi.org/10.1021/acssuschemeng.1c03118 https://doi.org/10.1039/C8TA03021A https://doi.org/10.1039/C8TA03021A https://doi.org/10.1039/c6cs00841k https://doi.org/10.1007/S11705-019-1886-0 https://doi.org/10.1016/J.MEMSCI.2019.117530 https://doi.org/10.1016/J.MEMSCI.2019.117530 https://doi.org/10.1016/J.MATT.2021.02.019 https://doi.org/10.1016/J.MATT.2021.02.019 https://doi.org/10.1039/D3GC00391D CHEN et al. 1503 membranes. J Membr Sci. 2021;639:119783. https://doi.org/10. 1016/J.MEMSCI.2021.119783 41. Widenmeyer M, Wiegers K-S, Chen G, Yoon S, Feldhoff A, Weidenkaff A. Engineering of oxygen pathways for better oxy- gen permeability in Cr-substituted Ba2In2O5 membranes. J Membr Sci. 2020;595:117558. https://doi.org/10.1016/J.MEMSCI. 2019.117558 42. Han N, Zhang C, Tan X, Wang Z, Kawi S, Liu S. Re-evaluation of La0.6Sr0.4Co0.2Fe0.8O3-δ hollow fiber membranes for oxygen separation after long-term storage of five and ten years. J Membr Sci. 2019;587:117180. https://doi.org/10.1016/J.MEMSCI. 2019.117180 43. Chen G, Liu W, Widenmeyer M, Ying P, Dou M, Xie W, et al. High flux and CO2-resistance of La0.6Ca0.4Co1–xFexO3−δ oxygen- transporting membranes. J Membr Sci. 2019;590:117082. https:// doi.org/10.1016/J.MEMSCI.2019.05.007 44. Ramasamy M, Baumann S, Palisaitis J, Schulze-Küppers F, Balaguer M, Kim D, et al. Influence of microstruc- ture and surface activation of dual-phase membrane Ce0.8Gd0.2O2−δ–FeCo2O4 on oxygen permeation. J Am Ceram Soc. 2016;99(1):349–55. https://doi.org/10.1111/JACE.13938 45. Du Z, Ma Y, Zhao H, Li K, Lu Y. High CO2-tolerant and cobalt-free dual-phase membranes for pure oxygen separation. J Membr Sci. 2019;574:243–51. https://doi.org/10.1016/j.memsci. 2018.12.083 46. He Y, Shi L, Wu F, Xie W, Wang S, Yan D, et al. A novel dual phase membrane 40 wt% Nd0.6Sr0.4CoO3-δ-60 wt% Ce0.9Nd0.1O2-δ: design, synthesis and properties. J Mater Chem A. 2017;6(1):84–92. https://doi.org/10.1039/c7ta07842k 47. Chen G, Zhao Z, Widenmeyer M, Yan R, Wang L, Feldhoff A, et al. Synthesis and characterization of 40 wt% Ce0.9Pr0.1O2–δ–60 wt%NdxSr1−xFe0.9Cu0.1O3−δ dual-phasemembranes for efficient oxygen separation. Membranes. 2020;10(8):183. https://doi.org/ 10.3390/MEMBRANES10080183 48. Liang F, Luo H, Partovi K, Ravkina O, Cao Z, Liu Yi, et al. A novel CO2-stable dual phase membrane with high oxygen per- meability. ChemCommun. 2014;50(19):2451–54. https://doi.org/ 10.1039/c3cc47962e 49. Li C, Song J, Zhang S, Tan X, Meng X, Sunarso J, et al. SDC- SCFZ dual-phase ceramics: structure, electrical conductivity, thermal expansion, and O2 permeability. J Am Ceram Soc. 2021;104(5):2268–84. https://doi.org/10.1111/JACE.17665 50. Zhang S, Li C, Meng X, Tan X, Zhu Z, Sunarso J, et al. CO2- resistant SDC-SSAF oxygen selective dual-phase hollow fiber membranes. Asia-Pac J ChemEng. 2020;15(6):e2528. https://doi. org/10.1002/apj.2528 51. Han N, Wei Q, Zhang S, Yang N, Liu S. Rational design via tailoring Mo content in La2Ni1-xMoxO4+δ to improve oxygen permeation properties in CO2 atmosphere. J Alloys Compd. 2019;806:153–62. https://doi.org/10.1016/j.jallcom.2019. 07.209 52. Li T, Kamhangdatepon T, Wang Bo, Hartley UW, Li K. New bio-inspired design for high-performance and highly robust La0.6Sr0.4Co0.2Fe0.8O3-Δ membranes for oxygen permeation. J Membr Sci. 2019;578:203–8. https://doi.org/10.1016/j.memsci. 2019.02.042 53. Han N, Chen R, Chang T, Li L, Wang H, Zeng L. A novel lanthanum strontium cobalt iron composite membrane syn- thesised through beneficial phase reaction for oxygen separa- tion. Ceram Int. 2019;45(15):18924–30. https://doi.org/10.1016/j. ceramint.2019.06.128 54. Wang T, Liu Z, Xu X, Zhu J, Zhang G, Jin W. Insights into the design of nineteen-channel perovskite hollow fiber membrane and its oxygen transport behaviour. J Membr Sci. 2020;595:117600. https://doi.org/10.1016/j.memsci.2019.117600 55. Zhang K, Shao Z, Li C, Liu S. Novel CO2-tolerant ion- transporting ceramic membranes with an external short cir- cuit for oxygen separation at intermediate temperatures. Energy Environ Sci. 2012;5(1):5257–64. https://doi.org/10.1039/ C1EE02539B 56. Meng X, Sunarso J, Jin Y, Bi X, Yang N, Tan X, et al. Robust CO2 and H2 resistant triple-layered (Ag- YSZ)/YSZ/(La0.8Sr0.2MnO3-δ-YSZ) hollow fiber membranes with short-circuit for oxygen permeation. J Membr Sci. 2017;524:596–603. https://doi.org/10.1016/J.MEMSCI.2016.11.071 57. Han N, Shen Z, Zhao X, Chen R, Thakur VK. Perovskite oxides for oxygen transport: chemistry and material hori- zons. Sci Total Environ. 2022;806:151213. https://doi.org/10.1016/ J.SCITOTENV.2021.151213 58. Jiang K, Liu Z, Zhang G, Jin W. A novel catalytic membrane reactor with homologous exsolution-based perovskite catalyst. J Membr Sci. 2020;608:118213. https://doi.org/10.1016/j.memsci. 2020.118213 59. Tan X, Li K. Applications of dense ceramic membrane reactors in selected oxidation and dehydrogenation processes for chemi- cal production. Handb Membr React. 2013;2:347–83. https://doi. org/10.1533/9780857097347.2.347 60. Han N, Zhang W, Guo W, Xie S, Zhang C, Zhang X, et al. Novel oxygen permeable hollow fiber perovskite membrane with sur- face wrinkles. Sep Purif Technol. 2021;261:118295. https://doi. org/10.1016/J.SEPPUR.2020.118295 61. Tan X, Wang Z, Liu H, Liu S. Enhancement of oxygen perme- ation through La0.6Sr0.4Co0.2Fe0.8O3−δ hollow fibre membranes by surface modifications. J Membr Sci. 2008;324(1–2):128–35. https://doi.org/10.1016/J.MEMSCI.2008.07.008 62. Zhu J, Dong Z, Liu Z, Zhang K, Zhang G, Jin W. Multichannel mixed-conducting hollow fiber membranes for oxygen separa- tion. AIChE J. 2014;60(6):1969–76. https://doi.org/10.1002/AIC. 14471 63. Zhu J, Wang T, Song Z, Liu Z, Zhang G, Jin W. Enhancing oxy- gen permeation via multiple types of oxygen transport paths in hepta-bore perovskite hollow fibers. AIChE J. 2017;63(10):4273– 7. https://doi.org/10.1002/AIC.15849 64. Lee M, Wu Z, Wang Bo, Li K. Micro-structured alumina multi-channel capillary tubes and monoliths. J Membr Sci. 2015;489:64–72. https://doi.org/10.1016/J.MEMSCI.2015.03.091 65. Zhu Y, Lei J, Liu J, Tan J, Zhang G, Liu Z, et al. Fabrication of CO2-tolerant SrFe0.8Nb0.2O3-δ/SrCo0.9Nb0.1O3-δ dual-layer 7- channel hollow fiber membrane by co-spinning and one-step thermal process. J Membr Sci. 2023;670:121346. https://doi.org/ 10.1016/J.MEMSCI.2023.121346 66. Zhang Z, Ning Ke, Xu Z, Zheng Q, Tan J, Liu Z, et al. Highly effi- cient preparation of Ce0.8Sm0.2O2-δ–SrCo0.9Nb0.1O3-δ dual-phase four-channel hollow fiber membrane via one-step thermal pro- cessing approach. J Membr Sci. 2021;620:118752. https://doi.org/ 10.1016/J.MEMSCI.2020.118752 67. Chi Y, Li T,Wang Bo,Wu Z, Li K.Morphology, performance and stability of multi-bore capillary La0.6Sr0.4Co0.2Fe0.8O3-δ oxygen https://doi.org/10.1016/J.MEMSCI.2021.119783 https://doi.org/10.1016/J.MEMSCI.2021.119783 https://doi.org/10.1016/J.MEMSCI.2019.117558 https://doi.org/10.1016/J.MEMSCI.2019.117558 https://doi.org/10.1016/J.MEMSCI.2019.117180 https://doi.org/10.1016/J.MEMSCI.2019.117180 https://doi.org/10.1016/J.MEMSCI.2019.05.007 https://doi.org/10.1016/J.MEMSCI.2019.05.007 https://doi.org/10.1111/JACE.13938 https://doi.org/10.1016/j.memsci.2018.12.083 https://doi.org/10.1016/j.memsci.2018.12.083 https://doi.org/10.1039/c7ta07842k https://doi.org/10.3390/MEMBRANES10080183 https://doi.org/10.3390/MEMBRANES10080183 https://doi.org/10.1039/c3cc47962e https://doi.org/10.1039/c3cc47962e https://doi.org/10.1111/JACE.17665 https://doi.org/10.1002/apj.2528 https://doi.org/10.1002/apj.2528 https://doi.org/10.1016/j.jallcom.2019.07.209 https://doi.org/10.1016/j.jallcom.2019.07.209 https://doi.org/10.1016/j.memsci.2019.02.042 https://doi.org/10.1016/j.memsci.2019.02.042 https://doi.org/10.1016/j.ceramint.2019.06.128 https://doi.org/10.1016/j.ceramint.2019.06.128 https://doi.org/10.1016/j.memsci.2019.117600 https://doi.org/10.1039/C1EE02539B https://doi.org/10.1039/C1EE02539B https://doi.org/10.1016/J.MEMSCI.2016.11.071 https://doi.org/10.1016/J.SCITOTENV.2021.151213 https://doi.org/10.1016/J.SCITOTENV.2021.151213 https://doi.org/10.1016/j.memsci.2020.118213 https://doi.org/10.1016/j.memsci.2020.118213 https://doi.org/10.1533/9780857097347.2.347 https://doi.org/10.1533/9780857097347.2.347 https://doi.org/10.1016/J.SEPPUR.2020.118295 https://doi.org/10.1016/J.SEPPUR.2020.118295 https://doi.org/10.1016/J.MEMSCI.2008.07.008 https://doi.org/10.1002/AIC.14471 https://doi.org/10.1002/AIC.14471 https://doi.org/10.1002/AIC.15849 https://doi.org/10.1016/J.MEMSCI.2015.03.091 https://doi.org/10.1016/J.MEMSCI.2023.121346 https://doi.org/10.1016/J.MEMSCI.2023.121346 https://doi.org/10.1016/J.MEMSCI.2020.118752 https://doi.org/10.1016/J.MEMSCI.2020.118752 1504 CHEN et al. transportmembranes. JMembr Sci. 2017;529:224–33. https://doi. org/10.1016/J.MEMSCI.2017.02.010 68. Chen G, Snyders R, Britun N. CO2 conversion using catalyst- free and catalyst-assisted plasma-processes: recent progress and understanding. J CO2 Util. 2021;49:101557. https://doi.org/10. 1016/J.JCOU.2021.101557 69. Chen G, Georgieva V, Godfroid T, Snyders R, Delplancke- Ogletree M-P. Plasma assisted catalytic decomposition of CO2. Appl Catal B Environ. 2016;190:115–24. https://doi.org/10.1016/J. APCATB.2016.03.009 70. Snoeckx R, Bogaerts A. Plasma technology—a novel solution for CO2 conversion? ChemSoc Rev. 2017;46(19):5805–63. https:// doi.org/10.1039/C6CS00066E 71. Chen G, Buck F, Kistner I, Widenmeyer M, Schiestel T, Schulz A, et al. A novel plasma-assisted hollow fiber membrane concept for efficiently separating oxygen from CO in a CO2 plasma. Chem Eng J. 2020;392:123699. https://doi.org/10.1016/J. CEJ.2019.123699 72. Buck F, Wiegers K, Schulz A, Schiestel T. MIEC hollow-fibre membranes in a plasma membrane reactor. Interceram—Int CeramRev. 2021;70(2):40–5. https://doi.org/10.1007/S42411-021- 0445-0 73. Buck F, Feldhoff A, Caro J, Schiestel T. Permeation improve- ment of LCCF hollow fiber membranes by spinning and sinter- ing optimization. Sep Purif Technol. 2021;259:118023. https://doi. org/10.1016/J.SEPPUR.2020.118023 74. Zheng Q, Xie Y, Tan J, Xu Z, Luo P, Wang T, et al. Coupling of dielectric barrier discharge plasma with oxygen permeable membrane for highly efficient low-temperature permeation. J Membr Sci. 2022;641:119896. https://doi.org/10.1016/J. MEMSCI.2021.119896 75. Tou M, Michalsky R, Steinfeld A. Solar-driven thermochemical splitting of CO2 and in situ separation of CO and O2 across a ceria redox membrane reactor. Joule. 2017;1(1):146–54. https:// doi.org/10.1016/J.JOULE.2017.07.015 76. Abanades S, Haeussler A, Julbe A. Thermochemical solar- driven reduction of CO2 into separate streams of CO and O2 via an isothermal oxygen-conducting ceria membrane reactor. Chem Eng J. 2021;422:130026. https://doi.org/10.1016/j.cej.2021. 130026 77. Tou M, Jin J, Hao Y, Steinfeld A, Michalsky R. Solar-driven co-thermolysis of CO2 and H2O and in-situ oxygen removal across a non-stoichiometric ceria membrane. React Chem Eng. 2019;4:1431–38. https://doi.org/10.1039/C8RE00218E 78. Zhang K, Sun S, Huang K. Oxidative coupling of methane (OCM) conversion into C2 products through a CO2/O2 co- transport membrane reactor. J Membr Sci. 2022;661:120915. https://doi.org/10.1016/J.MEMSCI.2022.120915 79. Sunarso J, Baumann S, Serra JM,MeulenbergWA, Liu S, Lin YS, et al. Mixed ionic–electronic conducting (MIEC) ceramic-based membranes for oxygen separation. J Membr Sci. 2008;320(1– 2):13–41. https://doi.org/10.1016/J.MEMSCI.2008.03.074 80. Dreimann JM, Kohls E, Warmeling HFW, Stein M, Guo LF, GarlandM, et al. In situ infrared spectroscopy as a tool for mon- itoring molecular catalyst for hydroformylation in continuous processes. ACS Catal. 2019;9(5):4308–19. https://doi.org/10.1021/ ACSCATAL.8B05066 81. Kang R, Zhang Z, Bin F, Wei X, Li Y, Chen G, et al. Catalytic ignition of CO over CuCeZr based catalysts: new insights into the support effects and reaction pathways. Appl Catal B Environ. 2023;327:122435. https://doi.org/10.1016/J.APCATB.2023.122435 82. Li C, Chew JJ, Mahmoud A, Liu S, Sunarso J. Modelling of oxygen transport through mixed ionic-electronic conducting (MIEC) ceramic-based membranes: an overview. J Membr Sci. 2018;567:228–60. https://doi.org/10.1016/J.MEMSCI.2018. 09.016 83. Tang X-Y, Yang W-W, Ma Xu, Cao XE. An integrated model- ing method for membrane reactors and optimization study of operating conditions. Energy. 2023;268:126730. https://doi.org/ 10.1016/J.ENERGY.2023.126730 84. Feng B, Song J, Wang Z, Dewangan N, Kawi S, Tan X. CFD modeling of the perovskite hollow fiber membrane modules for oxygen separation. Chem Eng Sci. 2021;230:116214. https://doi. org/10.1016/j.ces.2020.116214 85. Sommer DE, Kirchen P. Towards improved partial oxidation product yield in mixed ionic-electronic membrane reactors using CSTR and CFD modelling. Chem Eng Sci. 2019;195:11–22. https://doi.org/10.1016/j.ces.2018.11.033 86. Hong J, Kirchen P, Ghoniem AF. Numerical simulation of ion transport membrane reactors: oxygen permeation and transport and fuel conversion. J Membr Sci. 2012;407–408:71–85. https:// doi.org/10.1016/J.MEMSCI.2012.03.018 How to cite this article: Chen G, Widenmeyer M, Yu X, Han N, Tan X, Homm G, et al. Perspectives on achievements and challenges of oxygen transport dual-functional membrane reactors. J Am Ceram Soc. 2024;107:1490–1504. https://doi.org/10.1111/jace.19411 https://doi.org/10.1016/J.MEMSCI.2017.02.010 https://doi.org/10.1016/J.MEMSCI.2017.02.010 https://doi.org/10.1016/J.JCOU.2021.101557 https://doi.org/10.1016/J.JCOU.2021.101557 https://doi.org/10.1016/J.APCATB.2016.03.009 https://doi.org/10.1016/J.APCATB.2016.03.009 https://doi.org/10.1039/C6CS00066E https://doi.org/10.1039/C6CS00066E https://doi.org/10.1016/J.CEJ.2019.123699 https://doi.org/10.1016/J.CEJ.2019.123699 https://doi.org/10.1007/S42411-021-0445-0 https://doi.org/10.1007/S42411-021-0445-0 https://doi.org/10.1016/J.SEPPUR.2020.118023 https://doi.org/10.1016/J.SEPPUR.2020.118023 https://doi.org/10.1016/J.MEMSCI.2021.119896 https://doi.org/10.1016/J.MEMSCI.2021.119896 https://doi.org/10.1016/J.JOULE.2017.07.015 https://doi.org/10.1016/J.JOULE.2017.07.015 https://doi.org/10.1016/j.cej.2021.130026 https://doi.org/10.1016/j.cej.2021.130026 https://doi.org/10.1039/C8RE00218E https://doi.org/10.1016/J.MEMSCI.2022.120915 https://doi.org/10.1016/J.MEMSCI.2008.03.074 https://doi.org/10.1021/ACSCATAL.8B05066 https://doi.org/10.1021/ACSCATAL.8B05066 https://doi.org/10.1016/J.APCATB.2023.122435 https://doi.org/10.1016/J.MEMSCI.2018.09.016 https://doi.org/10.1016/J.MEMSCI.2018.09.016 https://doi.org/10.1016/J.ENERGY.2023.126730 https://doi.org/10.1016/J.ENERGY.2023.126730 https://doi.org/10.1016/j.ces.2020.116214 https://doi.org/10.1016/j.ces.2020.116214 https://doi.org/10.1016/j.ces.2018.11.033 https://doi.org/10.1016/J.MEMSCI.2012.03.018 https://doi.org/10.1016/J.MEMSCI.2012.03.018 https://doi.org/10.1111/jace.19411 Perspectives on achievements and challenges of oxygen transport dual-functional membrane reactors Abstract 1 | INTRODUCTION 2 | RECENT ACHIEVEMENTS AND FUTURE CHALLENGES 2.1 | Water splitting coupling with oxidative process 2.2 | Thermal decomposition of carbon dioxide by coupling with an oxidative process 2.3 | Decomposition of NOx by coupling with an oxidative process 3 | OPPORTUNITIES AND FUTURE RESEARCH DIRECTIONS 3.1 | Oxygen transport membrane material development 3.2 | Engineering of the membrane 3.3 | Innovation in the OTM reactors 3.4 | Reaction mechanisms in the dual-functional membrane reactors 4 | CONCLUSIONS ACKNOWLEDGMENTS CONFLICT OF INTEREST STATEMENT ORCID REFERENCES