311 results found
Yunsi C, Chong JY, Wang B, et al., 2020, Pristine graphene membranes supported on ceramic hollow fibre prepared via a sacrificial layer assisted CVD approach, Journal of Membrane Science, Vol: 595, Pages: 1-8, ISSN: 0376-7388
Graphene is a 2D ultra-thin material, when being used as membranes, potentially promises high permeation flux and can be operated in extreme conditions attributed to its chemical inertness. Currently, continuous atomic thin graphene membranes can only be made by chemical vapour deposition (CVD) on flat sheet, which limits its process intensification because of the low surface-area-to-volume ratio. To tackle this challenge, we have successfully devised an unprecedented method to fabricate graphene membranes supported on ceramic hollow fibre via a nickel sacrificial layer approach. It starts with coating a continuous dense nickel sacrificial layer on yttrium-stabilised zirconia (YSZ) hollow fibre via electroless plating, followed by synthesis of a continuous graphene layer by CVD. After that, thermal oxygen etching followed by nitric acid leaching were performed to successfully remove the nickel layer, and defect-patching treatment was carried out to eliminate any major defects formed during the leaching process. Herein, a continuous ultra-thin graphene layer sitting on YSZ hollow fibre was obtained. The achieved graphene hollow fibre membrane exhibits a methanol flux of 2.4 LMH (L m−2 h−1) bar−1 and a remarkable 98.8% rose bengal rejection. This study thus demonstrates a step towards successful engineering of pristine graphene membranes on micro-tubular supports.
Chong JY, Wang B, Sherrell PC, et al., 2019, Fabrication of graphene‐covered micro‐tubes for process intensification, Advanced Engineering Materials, Vol: 21, Pages: 1-6, ISSN: 1438-1656
Graphene is known for its high surface‐area‐to‐mass ratio. However, for graphene to be used in engineering processes such as catalytic reactors or heat exchangers, high surface‐area‐to‐volume ratio is essential. Currently, graphene is only prepared in sheet form, which limits its surface‐area‐to‐volume ratio to around 200 m2 m−3. In this study, we propose and demonstrate a technique based on chemical vapour deposition (CVD) to realise graphene on a copper‐based micro‐tubular substrate to not only substantially increase its surface‐area‐to‐volume ratio to a value over 2000 m2 m−3, but also to eliminate maldistribution of flows commonly unavoidable in flat‐sheet configurations. Our approach uses a dual‐layer micro‐tubular substrate fabricated by a phase‐inversion facilitated co‐extrusion technique. In the substrate, a thin copper outer layer is employed to enable the CVD growth of graphene, and an inner Cu‐Fe layer is adopted to provide a strong mechanical support. Our study shows that this approach is feasible to produce graphene with a very high surface‐area‐to‐volume ratio for possible practical applications in catalytic reactors or heat exchangers, though problems such as the inter‐diffusion between the two metal layers and defects in graphene need to be further addressed. To the best of our knowledge, this study is the first attempt to prepare graphene with high surface‐area‐to‐volume ratio by a CVD route.
Li T, Khamhangdatepon T, Wang B, et al., 2019, New bio-inspired design for high-performance and highly robust La0.6Sr0.4Co0.2Fe0.8O3-δ membranes for oxygen permeation, Journal of Membrane Science, Vol: 578, Pages: 203-208, ISSN: 0376-7388
Ceramic-based oxygen permeation membranes (OPM) are considered to be promising for the separation of oxygen from air. However, state-of-art membrane designs are unable to deliver satisfactory performances in terms of permeation flux, mechanical/chemical stability and membrane surface area. In this study, a new bio-inspired design has been successfully introduced in the micro-monolithic membranes made of La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) for oxygen separation. By carefully controlling the process parameters of the fabrication and utilizing the hydraulic pressure of internal coagulant, the geometry of channels in the micro-monolith has been converted from a circular shape to a triangle shape with rounded corners. This new bio-inspired, ‘orange-like’ architecture not only reduces the effective oxygen diffusional length down to approximately 50 µm, but also significantly increases the ratio of active region among the overall circumference up to 90%. This new bio-inspired micro-monolithic design displays an excellent oxygen permeation flux of 1.87 ml min-1cm-2 at 950 °C, which is superior to the most reported values from LSCF material systems. In addition, such a design illustrates an excellent mechanical robustness that has long been a bottleneck for LSCF membranes. This work demonstrates a promising solution to tackle the long-existing trade-off between oxygen permeation performance and mechanical reliability.
Li T, Heenan TMM, Rabuni MF, et al., 2019, Design of next-generation ceramic fuel cells and real-time characterization with synchrotron X-ray diffraction computed tomography, Nature Communications, Vol: 10, ISSN: 2041-1723
Ceramic fuel cells offer a clean and efficient means of producing electricity through a variety of fuels. However, miniaturization of cell dimensions for portable device application remains a challenge, as volumetric power densities generated by readily-available planar/tubular ceramic cells are limited. Here, we demonstrate a concept of ‘micro-monolithic’ ceramic cell design. The mechanical robustness and structural integrity of this design is thoroughly investigated with real-time, synchrotron X-ray diffraction computed tomography, suggesting excellent thermal cycling stability. The successful miniaturization results in an exceptional power density of 1.27 W cm−2 at 800 °C, which is among the highest reported. This holistic design incorporates both mechanical integrity and electrochemical performance, leading to mechanical property enhancement and representing an important step toward commercial development of portable ceramic devices with high volumetric power (>10 W cm−3), fast thermal cycling and marked mechanical reliability.
Li T, Heenan TMM, Rabuni MF, et al., Next-generation ceramic fuel cells: From new design to real-life characterization with synchrotron x-ray diffraction computed tomography, Nature Communications, ISSN: 2041-1723
Ceramic fuel cells offer a clean and efficient means of producing electricity through a variety of fuels. However, miniaturization of cell dimensions for portable device application remains a challenge, as volumetric power densities generated by readily-available planar/tubular ceramic cells are limited. Herein, we demonstrate a new concept of ‘micro-monolithic’ ceramic cell design. The mechanical robustness and structural integrity of this new design was thoroughly investigated with real-time, synchrotron X-ray diffraction computed tomography for the first time, suggesting excellent thermal cycling stability. The successful miniaturization resulted in an exceptional power density of 1.27 W cm-2 at 800 °C, which is one of the highest reported. This holistic design considers both mechanical integrity and electrochemical performance with mechanical property enhanced by a factor of 4-8, representing an important step toward for commercial development of portable ceramic devices with high volumetric power (>10 W cm-3), fast thermal cycling and marked mechanical reliability.
Mahyon NI, Li T, Martinez-Botas R, et al., 2019, A new hollow fibre catalytic converter design for sustainable automotive emissions control, CATALYSIS COMMUNICATIONS, Vol: 120, Pages: 86-90, ISSN: 1566-7367
Chi Y, Li T, Chong JY, et al., 2019, Graphene-protected nickel hollow fibre membrane and its application in the production of high-performance catalysts, Journal of Membrane Science, ISSN: 0376-7388
© 2019 Graphene as a protective coating has raised many interests. This ultra-thin material is chemically inert, and it is impermeable to gases and liquids, therefore it can act as a protective coating to enhance the lifespan and chemical resistance of metallic membranes. In this study, graphene protected nickel hollow fibre (G-Ni-HF) membrane was fabricated using the phase-inversion and facile single-stage sintering-chemical vapour deposition (CVD) process. The non-protected nickel hollow fibre membrane dissolved in nitric acid within a few hours, whereas the G-Ni-HF membrane remained intact. The as-prepared G-Ni-HF membrane featuring well-controlled pore structure, good chemical stability and mechanical robustness can be used in a variety of applications that involve harsh conditions. Here, we demonstrated its use in membrane emulsification to prepare TiO2 microspheres, where a highly acidic condition is essential. The microspheres prepared using G-Ni-HF membrane possess a hierarchical asymmetric egg-white structure that is distinct from the symmetric microspheres obtained by normal emulsification method. The asymmetric TiO2 microspheres also exhibit substantially improved catalytic activity to CO oxidation after impregnating with a palladium catalyst.
Huang K, Wang B, Chi Y, et al., 2018, High propylene selective metal-organic framework membranes prepared in confined spaces via convective circulation synthesis, Advanced Materials Interfaces, Vol: 5, Pages: 1-8, ISSN: 2196-7350
In this study, the successful preparation of defect‐free metal‐organic framework (MOF) membranes on the inner surface of ceramic hollow fibers and micromonoliths is reported for the first time. The prepared zeolitic imidazolite framework‐8 membranes exhibit impressively high propylene/propane (C3H6/C3H8) separation factor (up to 139), which is over an order of magnitude higher than that of traditional polymeric membranes. Such excellent results are achieved via a versatile convective circulation method, which eliminates the need of pumps for materials supply and is cost effective andenergy efficient. The MOF membranes prepared in this study show the potential in meeting stringent industrial requirements, as they have full protection from external impact during storage and module assembly, as well as high membrane surface area per volume, enabling compact devices for process intensification.
Lu X, Li T, Bertei A, et al., 2018, The application of hierarchical structures in energy devices: new insights into the design of solid oxide fuel cells with enhanced mass transport, ENERGY & ENVIRONMENTAL SCIENCE, Vol: 11, Pages: 2390-2403, ISSN: 1754-5692
Kang H, Wang B, Guo S, et al., 2018, Micropatterned ultrathin MOF membranes with enhanced molecular sieving property, Angewandte Chemie, Vol: 57, Pages: 13892-13896, ISSN: 1521-3757
Metal–organic frameworks (MOFs) are attractive crystalline materials for membranes due to their diverse crystalline pore structures and molecular separation properties. However, the fabrication cost is relatively high compared to conventional polymeric membranes. The concern of the cost could be eased if they are part of a value‐added device, for example, as the key separation unit in a lab‐on‐a‐chip device. This study demonstrates the feasibility of miniaturization of MOF membranes by patterning the membrane surface, a necessary step for MOF membranes to be used in compact devices. Water‐stable ultrathin UiO‐66 membranes with a thickness down to 250 nm on a substrate with a complex pattern were grown. The patterned membranes showed a 100 % improvement in the apparent permeation flux over conventional flat‐UiO‐66 membranes without compromising the molecular separation property, indicating the complexity of a surface would not be a formidable obstacle to the MOF membrane fabrication.
Ranieri G, Mazzei R, Poerio T, et al., 2018, Biorefinery of olive leaves to produce dry oleuropein aglycone: Use of homemade ceramic capillary biocatalytic membranes in a multiphase system, CHEMICAL ENGINEERING SCIENCE, Vol: 185, Pages: 149-156, ISSN: 0009-2509
Zhang W, Li K, 2018, Editorial overview: Separation engineering: Recent development in porous materials for efficient molecular separation, CURRENT OPINION IN CHEMICAL ENGINEERING, Vol: 20, Pages: A4-A5, ISSN: 2211-3398
Rabuni MF, Li T, Punmeechao P, et al., 2018, Electrode design for direct-methane micro-tubular solid oxide fuel cells (MT-SOFC), Journal of Power Sources, Vol: 384, Pages: 287-294, ISSN: 0378-7753
Herein, a micro-structured electrode design has been developed via a modified phase-inversion method. A thin electrolyte integrated with a highly porous anode scaffold has been fabricated in a single-step process and developed into a complete fuel cell for direct methane (CH4) utilisation. A continuous and well-dispersed layer of copper-ceria (Cu-CeO2) was incorporated inside the micro-channels of the anode scaffold. A complete cell was investigated for direct CH4 utilisation. The well-organised micro-channels and nano-structured Cu-CeO2 anode contributed to an increase in electrochemical reaction sites that promoted charge-transfer as well as facilitating gaseous fuel distribution, resulting in outstanding performances. Excellent electrochemical performances have been achieved in both hydrogen (H2) and CH4 operation. The power density of 0.16 Wcm−2 at 750 °C with dry CH4 as fuel is one of the highest ever reported values for similar anode materials.
Allenby MC, Tahlawi A, Morais JCF, et al., 2018, Ceramic hollow fibre constructs for continuous perfusion and cell harvest from 3D hematopoietic organoids, Stem Cells International, ISSN: 1687-9678
Tissue vasculature efficiently distributes nutrients, removes metabolites, and possesses selective cellular permeability for tissue growth and function. Engineered tissue models have been limited by small volumes, low cell densities, and invasive cell extraction due to ineffective nutrient diffusion and cell-biomaterial attachment. Herein, we describe the fabrication and testing of ceramic hollow fibre membranes (HFs) able to separate red blood cells (RBCs) and mononuclear cells (MNCs) and be incorporated into 3D tissue models to improve nutrient and metabolite exchange. These HFs filtered RBCs from human umbilical cord blood (CB) suspensions of 20% RBCs to produce 90% RBC filtrate suspensions. When incorporated within 5 mL of 3D collagen-coated polyurethane porous scaffold, medium-perfused HFs maintained nontoxic glucose, lactate, pH levels, and higher cell densities over 21 days of culture in comparison to nonperfused 0.125 mL scaffolds. This hollow fibre bioreactor (HFBR) required a smaller per-cell medium requirement and operated at cell densities > 10-fold higher than current 2D methods whilst allowing for continuous cell harvest through HFs. Herein, we propose HFs to improve 3D cell culture nutrient and metabolite diffusion, increase culture volume and cell density, and continuously harvest products for translational cell therapy biomanufacturing protocols.
Li K, Chong JY, Wang B, 2018, Water transport through graphene oxide membranes: the roles of driving forces, Chemical Communications, Vol: 54, Pages: 2554-2557, ISSN: 1359-7345
Graphene oxide (GO) membranes have shown excellent selectivities in nanofiltration and pervaporation. However, the water transport mechanisms in the unique membrane laminar structure are still not well understood, especially in pervaporation which involves selective permeation and evaporation. Herein, water transport in GO membranes was tested under two different modes: pressure-driven permeation and pervaporation. The pure water flux was found to be 1–2 orders of magnitude higher in pervaporation due to the large capillary pressure induced by evaporation. The water flux in pervaporation was suggested to be limited by evaporation at room temperature but surface diffusion at high temperature.
Araki S, Okabe A, Ogawa A, et al., 2018, Preparation and pervaporation performance of vinyl-functionalized silica membranes, JOURNAL OF MEMBRANE SCIENCE, Vol: 548, Pages: 66-72, ISSN: 0376-7388
Li K, Wang B, Chong JY, et al., 2017, Dynamic microstructure of graphene oxide membranes and the permeation flux, Journal of Membrane Science, Vol: 549, Pages: 385-392, ISSN: 0376-7388
Graphene oxide (GO) membranes have been reported to be a promising separation barrier that can retain small molecules and multi-valent salts because of the well-defined interlayer space between GO flakes. However, while some studies suggested fast liquid transport through the extremely tortuous transport path, contradictory observations (e.g. low permeation flux) have also been obtained. This paper revealed the dynamic microstructure of GO membranes, which affected the membrane performance significantly. We showed that all GO membranes prepared by varied methods and on different substrates presented a severe reduction in water permeability during filtration, due to the compaction of their original loose microstructure. The water flux could drop continuously from tens of LMH bar−1 to <0.1 LMH bar−1 after more than ten hours. This result demonstrated that the structure of GO membranes prepared by current approaches was far from the ideal laminar structure. The high permeability of GO membranes observed could be contributed by the disordered membrane microstructure. Therefore, the transport mechanisms assuming perfect laminar structure in GO membranes, and the fast transport hypothesis may not fully describe the water transport in GO membranes. Interestingly, the loosely packed microstructure of GO membranes was also found reversible depending on the storage conditions.
Li K, Wang B, Ji J, et al., 2017, Porous membranes prepared by a combined crystallisation and diffusion (CCD) method: study on formation mechanisms, Journal of Membrane Science, Vol: 548, Pages: 136-148, ISSN: 0376-7388
Currently, porous polymeric membranes are mainly produced by the NIPS and TIPS techniques, but both have intrinsic technical limitations in terms of effective control of membrane structures. Recently, a novel Combined solvent Crystallisation and polymer Diffusion (CCD) method has been established to produce high-performance membranes with a unique asymmetric structure, where solvent nucleation and crystallisation in a binary polymer-solvent system are utilised to serve as the pore-forming mechanism. However, the membrane formation mechanism of the CCD method has yet been understood fully. In this work, the formation mechanism is proposed based on the widely acknowledged principles of nucleation and crystal growth. A typical and commonly used amorphous polymer, polyethersulfone (PES) is employed as a sample membrane material to prepare microfiltration/ultrafiltration membranes using the CCD method and the effect of cooling rate on the membrane structure is investigated. The structural features of the membranes can be well explained using the proposed membrane formation mechanism, where the effect of cooling rate is rationalised. Pristine PES membranes with pore sizes < 20 nm and narrow pore size distribution can be achieved when a fast cooling rate is applied. Such membranes show a high pure water permeation flux, which is comparable to the nominal flux of commercial hydrophilic PES membranes with similar pore size.
Lu X, Taiwo OO, Bertei A, et al., 2017, Multi-length scale tomography for the determination and optimization of the effective microstructural properties in novel hierarchical solid oxide fuel cell anodes, JOURNAL OF POWER SOURCES, Vol: 367, Pages: 177-186, ISSN: 0378-7753
Garcia-Fernandez L, Wang B, Garcia-Payo MC, et al., 2017, Morphological design of alumina hollow fiber membranes for desalination by air gap membrane distillation, DESALINATION, Vol: 420, Pages: 226-240, ISSN: 0011-9164
Lu X, Heenan TMM, Bailey JJ, et al., 2017, Correlation between triple phase boundary and the microstructure of Solid Oxide Fuel Cell anodes: The role of composition, porosity and Ni densification, JOURNAL OF POWER SOURCES, Vol: 365, Pages: 210-219, ISSN: 0378-7753
Li K, Wang B, chong JY, 2017, High performance stainless steel-ceramic composite hollow fibres for microfiltration, Journal of Membrane Science, Vol: 541, Pages: 425-433, ISSN: 0376-7388
Stainless steel (SS) is an attractive material for membrane applications due to its excellent mechanical strength and chemical resistance. Compared to inorganic materials such as ceramic, SS is highly flexible and tough, and is easy to handle at industrial scale. Porous stainless steel hollow fibres can be fabricated by using the phase-inversion and sintering technique. While the sintering conditions have been well studied, the improvement in achieving smaller pore size of SS hollow fibres is still limited, constraining their practical applications. In our study, we introduce ceramic nanoparticles to fill up the large pores around SS particles. A phase-inversion assisted co-extrusion technique has been used to fabricate dual-layer SS/SS-ceramic hollow fibres in one step. The outer layer is a mixture of stainless steel and yttria-stabilized zirconia (YSZ), creating a separating layer with small pore sizes. The inner layer consists of SS, provides a strong mechanical strength to the hollow fibres. The mean pore size of the composite hollow fibre membranes can be reduced to approximately 300 nm, much smaller than the pore size of single-layer SS hollow fibres, which is generally larger than 1 μm. With improved mechanical strength compared to pure ceramic hollow fibres, the dual-layer SS/SS-YSZ hollow fibre membranes are also highly porous and the pure water flux can reach as high as ~3000 LMH bar-1, making them attractive in microfiltration for value-added products.
Li T, Lu X, Wang B, et al., 2017, X-ray tomography-assisted study of a phase inversion process in ceramic hollow fiber systems Towards practical structural design, JOURNAL OF MEMBRANE SCIENCE, Vol: 528, Pages: 24-33, ISSN: 0376-7388
Prasetya N, wu Z, Gouveia A, et al., 2017, Compact hollow fibre reactors for efficient methane conversion, Journal of the European Ceramic Society, Vol: 37, Pages: 5281-5287, ISSN: 1873-619X
In this study, a micro-structured catalytic hollow fiber membrane reactor (CHFMR) has been prepared, characterized and evaluated for performing steam methane reforming (SMR) reaction, using Rh/CeO2 as the catalyst and a palladium membrane for separating hydrogen from the reaction. Preliminary studies on a catalytic hollow fiber (CHF), a porous membrane reactor configuration without the palladium membrane, revealed that stable methane conversions reaching equilibrium values can be achieved, using approximately 36 mg of 2 wt.%Rh/CeO2 catalyst incorporated inside the micro-channels of alumina hollow fibre substrates (around 7 cm long in the reaction zone). This proves the advantages of efficiently utilizing catalysts in such a way, such as significantly reduced external mass transfer resistance when compared with conventional packed bed reactors. It is interesting to observe catalyst deactivation in CHF when the quantity of catalyst incorporated is less than 36 mg, although the Rh/CeO2 catalyst supposes to be quite resistant against carbon formation. The “shift” phenomenon expected in CHFMR was not observed by using 100 mg of 2 wt.%Rh/CeO2 catalyst, mainly due to the less desired catalyst packing at the presence of the dense Pd separating layer. Problems of this type were solved by using 100 mg of 4 wt.% Rh/CeO2 as the catalyst in CHFMR, resulting in methane conversion surpassing the equilibrium conversions and no detectable deactivation of the catalyst. As a result, the improved methodology of incorporating catalyst into the micro-channels of CHFMR is the key to a more efficient membrane reactor design of this type, for both the SMR in this study and the other catalytic reforming reactions.
Rahman MA, Mutalib MA, Li K, et al., 2017, Pore Size Measurements and Distribution for Ceramic Membranes, Membrane Characterization, Pages: 183-198, ISBN: 9780444637765
© 2017 Elsevier B.V. All rights reserved. This chapter discusses various methods in characterizing porous ceramic membranes. The fundamental theory and calculation for every approach are given to relate the basic concept of each technique to the results obtained from experiments. A number of techniques are discussed, including gas adsorption/desorption isotherm, permporometry, mercury porosimetry, thermoporometry, bubble point method, and liquid displacement technique. This chapter includes some step-by-step methodologies in obtaining the results of pore properties for ceramic membranes. The view and comparisons that include the advantages and limitations are given in the end of this chapter.
Chi Y, Li T, Wang B, et al., 2017, Morphology, performance and stability of multi-bore capillary La0.6Sr0.4Co0.2Fe0.8O3-δ oxygen transport membranes, Journal of Membrane Science, Vol: 529, Pages: 224-233, ISSN: 0376-7388
Mixed ionic-electronic conducting 3, 4, 7-bore capillary membranes made of La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) were successfully prepared by the combined phase inversion/sintering technique. The membranes fabricated have asymmetric wall structures with micro-channels formed in between surfaces, and dense layers sandwiched in between the micro-channels. By changing the solvent from DMSO to NMP, changes in the morphology of the 7-bore membrane were observed, where the separation layer has reduced its effective thickness. The multi-bore membranes exhibited 3-point bending fracture loads of 10.4, 13.5, 15.4 and 11.7 Newton with a 3 cm testing span for the 3-bore , 4-bore, 7-bore-DMSO and 7-bore-NMP samples, respectively, which are much stronger than single-bore hollow fibre membranes. Oxygen permeation of the multi-bore membranes was measured with a sweep gas flow through lumen and the effect of operating temperature has on the performance was studied between 750 °C to 1000 °C. Oxygen fluxes measured are comparable to typical sandwich-like structured single-bore hollow fibres at temperatures below 900 °C, but are notably higher at higher temperatures owe to their thinner membrane walls. The 200-hour long-term permeation test conducted on the 7-bore membrane showed a slight increase in permeation flux, but the sign of kinetic demixing/decomposition appeared on the outer surface, where the surface of the thinnest membrane walls underwent faster demixing/decomposition than the thickest walls. In summary, the results demonstrated that multi-bore configurations can achieve optimised material distribution during the fabrication, and can obtain strong mechanical property, high permeation flux for the final products whilst maintaining high membrane area to volume ratios.
Lu X, Tjaden B, Bertei A, et al., 2017, 3D characterization of diffusivities and its impact on mass flux and concentration overpotential in SOFC anodes, Journal of the Electrochemical Society, Vol: 164, Pages: F188-F195, ISSN: 0013-4651
In recent years great effort has been taken to understand the effect of gas transport on the performance of electrochemical devices. This study aims to characterize the diffusion regimes and the possible inaccuracies of the mass transport calculation in Solid Oxide Fuel Cell (SOFC) anodes when a volume-averaged pore diameter is used. 3D pore size distribution is measured based on the extracted pore phase from an X-ray CT scan, which is further used for the calculation of a Knudsen number (Kn) map in the porous medium, followed by the voxel-based distribution of the effective diffusion coefficients for different fuel gases. Diffusion fluxes in a binary gas mixture using the lower boundary, upper boundary and average effective coefficients are compared, and the impact on overpotential is analyzed. The results show that pore diameters from tens to hundreds of nanometers result in a broad range of Knudsen number (1.1 ∼ 4.8 and 0.6 ∼ 3 for H2 and CH4 respectively), indicative of the transitional diffusion regime. The results highlight that for a porous material, such as an SOFC anode where Knudsen effects are non-negligible, using a volume-averaged pore size can overestimate the mass flux by ±200% compared to the actual value. The characteristic pore size should be chosen sensibly in order to improve the reliability of the mass transport and electrochemical performance evaluation.
Lu X, Li T, Taiwo OO, et al., 2017, Study of the tortuosity factors at multi-scale for a novel-structured SOFC anode, 13th International X-Ray Microscopy Conference (XRM), Publisher: IOP PUBLISHING LTD, ISSN: 1742-6588
Liu X, Wang C, Wang B, et al., 2016, Novel Organics-Dehydration Membranes Prepared from Zirconium Metal-Organic Frameworks, Advanced Functional Materials, Vol: 27, ISSN: 1616-3028
Membranes with outstanding performance that are applicable in harsh environments are needed to broaden the current range of organics dehydration applications using pervaporation. Here, well-intergrown UiO-66 metal-organic framework membranes fabricated on pre-structured yttria-stabilized zirconia hollow fibers is reported via controlled solvothermal synthesis. On the basis of adsorption-diffusion mechanism, the membranes provides a very high flux of up to ca. 6.0 kg m-2 h-1 and excellent separation factor (> 45000) for separating water from i-butanol (next-generation biofuel), furfural (promising biochemical) and tetrahydrofuran (typical organic). This performance, in terms of separation factor, is one to two orders of magnitude higher than that of commercially available polymeric and silica membranes with equivalent flux. It is comparable to the performance of commercial zeolite NaA membranes. Additionally, the membrane remains robust during a pervaporation stability test (~300 hours), including exposure to harsh environments (e.g., boiling benzene, boiling water and sulfuric acid) where some commercial membranes (e.g., zeolite NaA membranes) cannot survive.
Li T, Rabuni MF, Kleiminger L, et al., 2016, Highly-robust solid oxide fuel cell (SOFC): simultaneous greenhouse gas treatment and clean energy generation, RSC Energy and Environment Series, Vol: 9, Pages: 3682-3686, ISSN: 2044-0774
Herein, results of combined greenhouse gas treatment with clean energy conversion is reported for the first time. Multi-channel tubular SOFCs were operated with N2O instead of air as the oxidant leading to a 50% increase in power density. Techno-economic evaluation suggested the feasibility of the combined approach eliminating the cost penalty for N2O abatement.
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