Silicalite nanosheet (SN) laminated membranes are promising for pervaporation (PV) desalination of concentrated brines for water purification and critical material concentration and recovery. However, scaling up the SN-based membranes is limited by inefficient synthesis of monodispersed open-pore SN single crystals (SNS). Here, we report a scalable approach to fabricate multilayered silicalite nanosheet plate (SNP) laminated membranes on porous alumina and PVDF substrates and demonstrate their excellent PV desalination performance for simulated brines containing lithium and high total dissolved salts (TDS). At 73 ± 3 °C, the SNP laminated membrane on alumina support achieved a remarkable water flux (Jw) of nearly 20 L/m2·h, significantly outperforming the alumina-supported SNS laminated membrane (Jw = 9.56 L/m2·h), while both provided near-complete salt rejection (ri ~99.9%) when operating with vacuum pressure on the permeate side. The PVDF-supported SNS and SNP laminated membranes exhibited excellent Jw (14.0 L/m2·h) and near-complete ri (>99.9%), surpassing the alumina-support SNP laminated membranes when operating by air sweep on the permeate side. However, the ri of the PVDF-supported membranes was found to decline when operating with vacuum pressure on the permeate side that was apparently caused by minimal liquid permeation through the inter-SNP spaces driven by the transmembrane pressure. With scalable SNP production, SNP-A membranes show potential for PV desalination of high-TDS solutions, especially in harsh environments unsuitable for polymer membranes.

This article reports the synthesis, characterization, and performance evaluation of a new anion-exchange membrane (AEM) comprising silicalite nanosheets (SNs) uniformly dispersed in a polybenzimidazole (PBI) matrix (SN-PBI). The SNs are two unit cells thick along the b-direction and contain surface quaternary ammonium groups (QAGs) derived from the diquaternary bis-1,5(tripropylammonium) pentamethylene diiodide (dC5) templates. These surface QAGs provide exchangeable hydroxide ions for efficient ion conduction through hydrated SN/PBI interfacial regions. With a thickness of ~20 µm and 5wt.% SN, the SN-PBI membrane exhibited a low area-specific resistance of ~0.105 Ω·cm², along with superior mechanical strength and gas crossover resistance compared with the commercial FAA-3-50® membrane. When operated with NiFe₂O₄ anode and Ni cathode for water electrolysis in 3 M KOH, the SN-PBI achieved a current density of 5 A cm⁻² at 2.75 V and 60 °C, outperforming the commercial FAA-3-50® membrane, which required 3.44 V at the same current density. The SN-PBI also demonstrated good operational stability, with less than 1% voltage decay over more than 100 h of operation. These results demonstrate the strong potential of SN-PBI for high-performance AEM water electrolysis and other alkaline electrochemical cells.

In the original publication [...].

Silicalite nanosheets (SNs) with surfaced quaternary ammonium cations of the template molecules are demonstrated as a new paradigm of building blocks for anion exchange membranes (AEMs). A multilayered SN membrane is fabricated on porous PVDF to achieve 3 A cm-2 at 2.35 V and coulombic efficiency of 97% in alkaline water electrolysis.

The first liquid gallium–CO2 battery achieves unprecedented power density and carbon negative effect without precious metal catalysts.

The growth of renewable energy sources presents a pressing challenge to the operation and maintenance of existing fossil fuel power plants, given that fossil fuel remains the predominant fuel source, responsible for over 60% of electricity generation in the United States. One of the main concerns within these fossil fuel power plants is the unpredictable failure of boiler tubes, resulting in emergency maintenance with significant economic and societal consequences. A reliable high-temperature sensor is necessary for in situ monitoring of boiler tubes and the safety of fossil fuel power plants. In this study, a comprehensive four-stage multi-physics computational framework is developed to assist the design, optimization installation, and operation of the high-temperature stainless-steel and quartz coaxial cable sensor (SSQ-CCS) for coal-fired boiler applications. With the consideration of various operation conditions, we predict the distributions of flue gas temperatures within coal-fired boilers, the temperature correlation between the boiler tube and SSQ-CCS, and the safety of SSQ-CCS. With the simulation-guided sensor installation plan, the newly designed SSQ-CCSs have been employed for field testing for more than 430 days. The computational framework developed in this work can guide the future operation of coal-fired plants and other power plants for the safety prediction of boiler operations.

Single crystalline ZSM-5 ZNs with thicknesses around 6 nm were obtained by secondary growth of silicalite nanoparticles using diquaternary bis-1,5(tripropyl ammonium) pentamethylene diiodide (dC5) as a structure-directing agent (SDA). The dC5 could be effectively removed from the ZN pores by either high-temperature calcination or UV irradiation in air at room temperature but not by the piranha solution treatment. Ultrathin ZN-laminated membranes (ZNLMs) were fabricated by sandwiching a UV-activated multilayered ZN film between two recast Nafion® layers (ZNLM-Nafion) and by filtration coating from a suspension of thermally activated ZNs on a nonionic porous PVDF (ZNLM-PVDF). The ZNLMs on both supports demonstrated the ability of highly proton-selective ion conduction with low resistances in aqueous electrolyte solutions. The ZNLM-PVDF with PVDF binder was structurally stable, and it achieved a comparably low ASR but much higher proton selectivity compared with a Nafion membrane of same overall thickness. However, detachment between the ZNLM and Nafion layers occurred when the ZNLM-Nafion operated in aqueous electrolyte solutions. Results of this study show the potential for developing ZNLMs as efficient proton-conducting membranes without using expensive ionic polymer matrices. However, the development of polymer-supported ZNLMs is hindered by the current inefficiency in preparing well-dispersed suspensions of open-pore ZNs. Future development of efficient methods for synthesizing open-pore ZNs in dispersed states is key to realizing high-performance ZNLMs on polymers.

Preactivated MFI zeolite nanosheet plates (ZNPs) with large areas (-2.0 x 2.0 mu m2) and nanometer thicknesses (-60 nm) were prepared directly in liquid-dispersed state. The individual ZNP was a stack of 4-nm-thick single crystalline zeolite nanosheets (ZNs) interlinked by Si-O-Si bonds between neighboring ZN surfaces. The dispersed open-pore ZNPs allowed formulating suspensions for tiling ZNP membranes on polymer substrates without requiring post-coating activation. A pinhole-free ZNP-tiled (ZNPT) membrane has been achieved on macroporous PVDF film by a self-repairing vacuum-assisted filtration coating method. The resultant ZNPT layer was-500 nm-thick consisting of about 7 ZNP layers with inter-ZNP width and inter-ZNP entrance porosity around 9 nm and 2%, respectively. The ZNPT-PVDF membrane exhibited high selectivity to proton transport over vanadyl ion and low resistances to proton conduction in aqueous solutions. The membrane also demon-strated to function as an efficient ion separator for the vanadium redox flow battery. The reported synthesis of preactivated ZNP suspension may overcome the major hurdle to realizing polymer-supported ZN membranes, which is the inefficiency of existing methods in obtaining readily dispersible open-pore ZNs. The ZNPT-PVDF membrane can be a more affordable and sustainable alternative to the Nafion-based ion separation membranes.

In this work, Ce and Cr/Co co-doped iron oxide (FeCeMOx, where M = Cr or Co) ferrites were investigated for high-temperature water-gas shift (HT-WGS) under industrially relevant pressures (20 bars). The Ce and Cr/Co bi-doping has greatly promoted the catalytic performance in comparison to the single Ce-doping. Especially, the FeCeCoOx ferrite demonstrated the best HT-WGS activity without any deactivation at a steam to CO ratio of 3.5. The ternary FeCeCrOx and FeCeCoOx catalysts also exhibited reasonably stable performance with a slight methanation activity (<2.5%) even under low steam to CO ratio of 1.5. The hematite phase (Fe2-xCex/2Mx/2O3, where M = Cr or Co and x = 0.33) of the fresh (calcined) catalysts became [A((1-delta))B(delta)](T) [A(delta)B((2-delta))]O-O(4) type magnetite spinel structure (Fe3-xCex/2Mx/2O4, where M = Cr or Co and x = 0.5) during the activation process, which is regarded as the active phase for the WGS reaction. The co-doping of Cr or Co increased the stability of the active magnetite phase against sintering and suppressed the coke formation during the WGS reaction, which should be responsible for the stable activity. The addition of Cr or Co to iron oxide also delays the formation and over-reduction of active magnetite phase. Mossbauer spectra confirmed that the Cr or Co ions were incorporated into the octahedral sites of [A((1-delta))B(delta)](T)[A(delta)B((2-delta))]O-O(4) spinel framework during the activation and modifies the local structure. The superparamagnetic behavior of the spinel ferrites has significantly enhanced upon the co-doping of Ce and Cr/Co into the iron oxide lattice, indicating a high fraction of nanoparticles in the ternary spinel ferrites. The Cr or Co addition resulted in the decreased surface Fe3+/Fe2+ ratio which could be due to the replacement of Fe3+ ions by Cr or Co ions. Most importantly, no evident change was observed in the surface structure of ternary spinel ferrites even after the reaction, which could be responsible the stable performance of the catalysts. Published by Elsevier Inc.

Catalytic decomposition of methane (CDM) to H2 and multiwalled carbon nanotubes (MWCNTs) was achieved by a nanocrystalline Cr-doped ferrite (FeCr) catalyst at 500 °C and atmospheric pressure with minor cofed CO. The exothermic Boudouard reaction increased the temperature and H2 from CDM at catalyst surface that induced Fe2+ reduction to Fe0. The Fe0 clusters along with the CO-originated surface oxygens enabled transfer of C and H to sustain the surface CDM and CO reactions. The metallic Fe-enabled C transfer led to the formation of MWCNTs. The Cr6+/3+ dopants facilitated the Fe redox cycles and maintained surface oxygens for high catalytic activity.

Zeolite nanosheets (ZNs) offer improved micropore accessibilities and transport properties for enhanced molecular catalysis and separations. However, practical application of the ZN materials is hampered by the lack of efficient synthesis methods. Here, a ZN self-seeded method is demonstrated for single-step reproduction of flower-like assemblies of very large MFI ZN plates. The ZN plates are ~60 nm-thick stacks of 4-nm-thick single crystal sheets. The ZN flower growth involves terrace nucleation on the seed surfaces and subsequent ZN epitaxial growth in [010] orientation directed by a diquaternary agent. The open architecture of the assemblies prevented collapse and agglomeration of ZNs during thermal activation that effectively preserved the interconnected intra-sheet and inter-sheet micropore system. Thus, the ZN assemblies exhibited markedly enhanced molecular adsorption capacity and transport diffusivity for the probing xylene molecules as compared to the conventional crystals. The ZN assembly and its harvestable very large-sized ZNs have the potential for developing high-performance ZN adsorbents, catalysts, and molecular-sieve membranes.

The frequency-dependent dielectric constant is a basic fluid property that is currently challenging to determine for complex liquid mixtures. Here, we report the determination of effective dielectric constants for various solvent mixtures under flow conditions using a simple in-line microwave Fabry-Pérot interferometer cable sensor. An ideal solution model-based mixing rule has been established and demonstrated for significantly improved prediction of dielectric constants for single-phase solvent mixtures. However, the current mixing rules exhibit large deviations for immiscible water/oil dispersions apparently because of the effects of strong interfacial polarizations on the overall mixture polarizability that are not accounted for by the models.

Nearly 30% of the electricity is generated by using coal as the primary fuel in the US. One of the major concerns in coal-fired power plants is the failure of boiler tubes that leads to unscheduled maintenance and has a huge economical and societal impact. High temperature flue gas along with ash pass over the boiler tubes, which over time leads to tube failure. Therefore, developing temperature sensors for harsh environments and install them for temperature sensing and boiler tube lifetime prediction is an urgent need. On the side of sensor development, the location of the sensor installation is important for stable sensing performance and easy calibration. In this study, computational fluid dynamics and heat transfer modeling are adopted to establish a full-scale 3-dimensional model of a coal-fired boiler to investigate the flue gas temperature distribution within the boiler and identify the proper locations for sensor installation. We proposed three criteria to select the temperature sensor installation location: (1) select the boiler tube panel away from the sidewalls, (2) select the boiler tube section closer to the top wall of the boiler; and (3) select the boiler tube on the back of the boiler panel (not directly facing the flue gas flow). In these regions, the flue gas temperature is stable, providing an ideal environment for stable temperature sensing and calibration.

A submicrometer-thick molecular sieve zeolite nanosheet laminated (ZNL) membrane has been synthesized on macroporous polyvinylidene fluoride (PVDF) substrate via the simplistic vacuum filtration-coating method. The membrane has been demonstrated with extraordinary water flux (similar to 11 kg/m(2).h) and salt rejection (similar to 99.9%) in pervaporation (PV) desalination of a multicomponent brine with 22 wt % of total dissolved salts (TDS) including Li+, Na+, K+, Mg2+, Cl-, and SO42-, etc. The desalination of high-salinity brines is critical to treatment and beneficial use of many industrial produced waters. The large aspect ratios (>100) and preferable b-orientation of the densely layered nanosheets make the solution dewatering rate surpass the ion diffusion rates in the nanoscale internanosheet spaces. This unique transport behavior effectively prevents the dissolved salts from migrating through the ZNL layer and stabilizes the water flux and ion rejection rates. The supported multilayered ZNL membrane, which is interlocked by the substrate-type PVDF binder, exhibits structure and performance stability in PV desalination of high-TDS brines.

A metal ceramic coaxial cable (MCCC) sensor containing multiple Fabry-Perot interferometers (FPIs) has been designed, fabricated, and evaluated for measuring distributed high temperatures. The MCCC sensor demonstrated here consists of stainless steel tube and wire conductors, alumina tube insulator, and three pairs of air gap reflectors distributed along the cable. The multipoint sensor operation is realized by the joint time-frequency domain technique, which combines the functions of time-domain reflectometry and frequency division multiplexing to enable the measurement of spatially distributed temperature. The 3-point MCCC-FPI sensor has been demonstrated for distributed temperature measurements between 250 and 550 degrees C and operability up to 1000 degrees C. The sensor offers high sensitivity of >0.18 MHz/degrees C with a measurement resolution of 1 Hz and reasonably small high temperature measurement error range of +/- 3 degrees C. (C) 2020 Elsevier Ltd. All rights reserved.

Herein, the catalytic performance of Fe/Nb/M (M = Mn, Co, Ni, and Cu) spinel ferrites prepared by a co-precipitation method for the high-temperature water-gas shift (HT-WGS) was investigated. Incorporation of Nb into the iron oxide lattice was found to moderately improve the catalytic activity. Conversely, the co-doping with Nb and transition metals (Mn, Co, Ni, and Cu) into the iron oxide matrix drastically enhanced the HT-WGS activity. The high lattice strain/disorder and facile Fe3+/Fe2+ redox cycle induced by the enhanced synergism in the Fe/Nb/M ternary catalysts serve as active sites to efficiently catalyze the WGS reaction. The results also indicate that the Nb acts as a textural promoter to improve the thermal stability of the active magnetite phase, while the transition metals act as structural promoters to enhance the WGS activity. The Fe/Nb/Ni exhibited the higher catalytic performance among the co-doped spinel ferrite catalysts. The high lattice strain/disorder, facile reduction of hematite to magnetite and highly facilitated surface Fe3+/Fe2+ redox pair by strong synergistic effect could be responsible for the better activity and stability of Fe/Nb/Ni in HT-WGS reaction. The characterizations of the spent Fe/Nb/Ni after 100 h of reaction revealed that the catalyst exhibited an excellent structural and surface stability during the reaction.

Water-gas shift (WGS) reaction followed by carbon dioxide (CO2) separation is a critical step in the integrated gasification combined cycle (IGCC) process for fossil-fuel-fired electrical power generation with CO2 capture. To intensify the IGCC process hydrogen-permselective zeolite membrane reactor offers promise to replace the conventional energy-intensive fixed-bed reactors and solvent-based CO2 capture units. The objectives of this project were to develop a bench-scale zeolite membrane reactor (total membrane area: 932 cm2 for a 21-tube membrane bundle) for the water-gas-shift reaction of raw syngas from an oxygen-blown coal-gasifier for H2 production with simultaneous CO2 separation at the capability of about 2 kilograms H2 per day (equivalent to 2 kW IGCC power plant) and to demonstrate significant progress toward achieving overall performance goal of 90% CO2 capture rate with 95% CO2 purity at the cost of electricity 30% less than the baseline carbon capture approaches. This report summarizes results obtained in this project on scaling up the zeolite membrane reactor by a factor of 200 in membrane area, tests of the bench-scale zeolite membrane reactor for the water-gas-shift reaction at high temperature and high-pressure, and techno-economic analysis of the integration of the zeolite membrane reactor in IGCC power plant for the electrical generation with CO2 capture. With effective pore modification by catalytic cracking deposition of MDES (methyldiethoxysilane), fabrication of MFI-type zeolite membranes was successfully scaled-up from a lab-scale disk type to bench-scale multiple-tube bundles on low-cost alumina supports. A Co-Mo based sour shift catalyst was evaluated and used in the zeolite membrane reactors for water-gas-shift reaction. The reaction kinetic and gas-permeation equations were developed and employed in mathematic models to guide/predict experiments/performance of zeolite membrane reactors for water-gas shift reaction. Multiple-tube zeolite membrane bundles and reactors were designed, fabricated and tested for gas separation and water-gas-shift reactions with real raw syngas from a coal-fired gasifier operated at high temperature and pressure. The zeolite membrane reactors demonstrated good long-term thermal and chemical stability and constant H2 permeance (>300 GPU) together with a Knudsen selectivity (~4.7) for H2 over CO2 in the field test (cumulative time >28 hours) with high-sulfur coal-derived syngas. The zeolite-membrane-reactor integrated IGCC process was designed using the performance experimentally measured by the University of Cincinnati team with a single-tube zeolite membrane reactor that offers a CO conversion >98% with more than 90% of CO2 and H2 captured. With the above integrative approaches, a techno-economic analysis for a cost-benefit comparison was performed to uncover features that determine the power output, capital expenditure, operating expenditure, cost of electricity and cost of CO2 capture in a 550-MW zeolite-membrane-reactor integrated IGCC process. The integration of the zeolite membrane reactor in IGCC could provide a significant reduction of 80% and 27% in the power consumption for Selexol™ Acid Gas Removal and CO2 compression, respectively, which lowers the total auxiliary power consumption by 12.5%. However, the low pressure required at permeate stream for maintaining the driving force of hydrogen permeation through the zeolite membrane costs a huge power in permeate compressor, compensating the power consumption reduction achieved with the membrane reactor. Thus, for coal-fired IGCC for electricity generation with 90% CO2 captured, the integration of the membrane reactor could provide a CO conversion ~99% and a significant drop in cost-of-electricity using zeolite membrane with H2 permeance >600 GPU and the H2/CO2 selectivity over 70.

Non-aqueous redox flow batteries (RFBs) are promising energy storage devices owing to the broad electrochemical window of organic solvents. Nonetheless, the wide application of these batteries has been limited by the low stability and limited solubility of organic materials, as well as the insufficient ion conductivity of the cell separators in non-aqueous electrolytes. In this study, two viologen analogues with poly(ethylene glycol) (PEG) tails are designed as anolytes for non-aqueous RFBs. The PEGylation of viologen not only enhances the solubility in acetonitrile but also increases the overall molecular size for alleviated crossover. In addition, a composite nanoporous aramid nanofiber separator, which allows the permeation of supporting ions while inhibiting the crossover of the designer viologens, is developed using a scalable doctor-blading method. Paired with ferrocene, the full organic material-based RFB presents excellent cyclability (500 cycles) with a retention capacity per cycle of 99.93% and an average Coulombic efficiency of 99.3% at a current density of 2.0 mA/cm2. The high performance of the PEGylated viologen validates the potential of the PEGylation strategy for enhanced organic material-based non-aqueous RFBs.

A nanocrystalline chromium-doped ferrite (FeCr) catalyst was shown to coproduce H2 and multiwalled carbon nanotubes (MWCNTs) during water gas shift (WGS) reaction in a H2-permselective zeolite membrane reactor (MR) at reaction pressures of ~20 bar. The FeCr catalyst was further demonstrated in the synthesis of highly crystalline and dimensionally uniform MWCNTs from a dry gas mixture of CO and CH4, which were the apparent sources for MWCNT growth in the WGS MR. In both the WGS MR and dry gas reactions, the operating temperature was 500 °C, which is significantly lower than those commonly used in MWCNT production by chemical vapor deposition (CVD) method from CO, CH4, or any other precursor gases. Extensive ex situ characterizations of the reaction products revealed that the FeCr catalyst remained in partially reduced states of Fe3+/Fe2+ and Cr6+/Cr3+ in WGS membrane reaction while further reduction of Fe2+ to Fe0 occurred in the CO/CH4 dry gas environments. The formation of the metallic Fe nanoparticles or catalyst surface dramatically improved the crystallinity and dimensional uniformity of the MWCNTs from dry gas reaction as compared to that from WGS reaction in the MR. Reaction of the CO/CH4 mixture containing 500 ppmv H2S also resulted in high-quality MWCNTs similar to those from the H2S-free feed gas, demonstrating excellent sulfur tolerance of the FeCr catalyst that is practically meaningful for utilization of biogas and cheap coal-derived syngas.