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Facilitated transport membranes containing silver ions have attracted much attention thanks to their high performance in olefin/paraffin separation. However, the poor long-term stability of such membranes remains a drawback that must be overcome to enable their practical use. In this work, silver ions were incorporated as ion complexes in the Pebax®2533 matrix to increase their stability as a function of time. Two complexing agents were evaluated: ammonia and 15-crown-5-ether. Membranes of Pebax®2533/Ag(NH3)2OH and Pebax®2533/[Ag(15-crown-5-ether)]BF4 maintained stable selectivity for more than thirty days of observation without compromising permeability. Although complexation decreases the performance of silver compared to free ions, it significantly increases the long-term performance in ethylene/ethane separation. the complexing agents weaken the intensity and strength of Ag+/ethylene-π complexation, but prevent the reduction of Ag(I) to Ag(0). In long-term single gas permeation tests, the Pebax®2533/Ag(NH3)2OH membrane showed selectivity in the range of 12.3 to 9 for 39 days, while the Pebax®2533/[Ag(15crown-5-ether)]BF4 membrane showed selectivity around 9 for 30 days. Mixed gas permeation studies allowed to identify conditions to maintain the separation performance above the upper bound for more than 40 days, under continuous membranes exposure to mixed gases. Increased stability compared to membranes reported in the literature was achieved.

The SuperCam instrument, onboard the Perseverance rover (Mars 2020 mission) is designed to perform remote analysis on the Martian surface employing several spectroscopic techniques such as Laser Induced Breakdown Spectroscopy (LIBS), Time-Resolved Raman (TRR), Time-Resolved Fluorescence (TRF) and Visible and Infrared (VISIR) reflectance. In addition, SuperCam also acquires high-resolution images using a color remote micro-imager (RMI) as well as sounds with its microphone. SuperCam has three main subsystems, the Mast Unit (MU) where the laser for chemical analysis and collection optics are housed, the Body Unit (BU) where the different spectrometers are located inside the rover, and the SuperCam Calibration Target (SCCT) located on the rover's deck to facilitate calibration tests at similar ambient conditions as the analyzed samples. To perform adequate calibrations on Mars, the 22 mineral samples included in the complex SCCT assembly must have a very homogeneous distribution of major and minor elements. The analysis and verification of such homogeneity for the 5-6 replicates of the samples included in the SCCT has been the aim of this work. To verify the physic-chemical homogeneity of the calibration targets, micro Energy Dispersive X-ray Fluorescence (EDXRF) imaging was first used on the whole surface of the targets, then the relative abundances of the detected elements were computed on 20 randomly distributed areas of 100*100 mum. For those targets showing a positive Raman response, micro-Raman spectroscopy imaging was performed on the whole surface of the targets at a resolution of 100*100 mum. The %RSD values (percent of relative standard deviation of mean values) for the major elements measured with EDXRF were compared with similar values obtained by two independent LIBS set-ups at spot sizes of 300 mum in diameter. The statistical analysis showed which elements were homogeneously distributed in the 22 mineral targets of the SCCT, providing their uncertainty values for further calibration. Moreover, nine of the 22 targets showed a good Raman response and their mineral distributions were also studied. Those targets can be also used for calibration purposes of the Raman part of SuperCam using the wavenumbers of their main Raman bands proposed in this work. The authors would like to thank the Spanish Agency for Research, projects ESP2015-71965-REDT, ESP2017-87690-C3-1-R and RED2018-102600-T for funding as well as to local and regional institutions including the Basque Government, the University of the Basque Country, the Junta de Castilla y León, the University of Valladolid and the University of Malaga for their support. Support in the US was provided by NASA's Mars Exploration Program. Support in France was provided by CNES, CNRS, and local Universities. The Danish contribution was funded through support by the Carlsberg Foundation, grants CF16-0981 and CF17-0979. The team from the University of the Basque Country is very grateful to Sebastien Maussang and Victor Escobar from Renishaw for having faith in our work. The suggestions from T.R. Gabriel are gratefully acknowledged.

The thermal distillation of crude oil mixtures is an energy intensive process conducted on massive scale worldwide. Membrane-based separations are, in principle, much more efficient in energetic terms, if useful fractions can be obtained. We describe here a family of spirocyclic polytriazoles for membrane applications prepared by a convenient step-growth method using copper-catalyzed azide-alkyne cycloaddition, providing very fast reaction rates, high molecular weights and solubilities in common organic solvents, and non-interconnected microporosity. Fractionation of whole Arabian light crude oil and atmospheric tower bottoms feeds using these materials significantly enriched the low-boiling components and removed trace heteroatom and metal impurities, demonstrating opportunities to reduce the energy cost of crude oil distillation with tandem membrane processes. Membrane-based molecular separation under these demanding conditions is made possible by high thermal stability and a moderate level of dynamic chain mobility leading to transient interconnections between micropores, as revealed by calculations of static and swollen pore structures.

Recent major discoveries of gas and oil in the United States in shale plays have significantly increased the amount of ethane available for steam-cracking to produce ethylene; and numerous large pe...

In this work, we demonstrate the process and economic viability of a new production route for methanol utilizing captured CO2 and H2 produced from renewable, photocatalytic water splitting. Initial assessments of H2 production from this approach revealed a low-cost potential through inexpensive feedstock, but with one major drawback. Simultaneous production of H2 and O2 increases the risk of forming an explosive mixture. In our previous work, we identified membrane-based processes to safely recover the H2 product. To reduce the H2 capture costs, we developed a conceptual process comprised of integrated facilities to produce methanol while solving the flammability constraints. The first unit supplies captured CO2, which is used as a raw material and a diluent to recover H2 from the photocatalytic reactors. The tertiary mixture (H2/O2/CO2) is safely processed in an optimized membrane-based separation plant to produce a 3:1 H2 and CO2 mixture. This binary mixture is then used as feedstock for methanol production via direct CO2 hydrogenation. Based on a detailed economic analysis, the break-even value of the methanol produced is higher than the current market price. The main drivers for the high cost are the separation plant and the feedstock costs of CO2. The best-case scenario (for the selected parameters), where the plant lifetime is 30 years with 0.060 $/kWh electricity price and 0.020 $/kg CO2 cost, has a break-even value for methanol at 0.96 $/kg. Based on a target solar-to-hydrogen efficiency of 10% in the photocatalytic reactor, the gross energy efficiency of the process was 6.25%. As a final element, we compared our process with alternative renewable methanol synthesis route from the literature to highlight the differences in electrochemical and thermochemical approaches.

Objective Approximately 30% of patients with type 2 diabetes mellitus have knee osteoarthritis. IA corticosteroids used to manage osteoarthritis pain can elevate blood glucose in these patients. We compared blood glucose levels following intra-articular injection of triamcinolone acetonide extended-release (TA-ER), an extended-release, microsphere-based triamcinolone acetonide formulation, vs standard triamcinolone acetonide crystalline suspension (TAcs) in patients with knee osteoarthritis and comorbid type 2 diabetes. Methods In this double-blind, randomized, parallel-group, phase 2 study (NCT02762370), 33 patients with knee osteoarthritis (American College of Rheumatology criteria) and type 2 diabetes mellitus (HbA1c 6.5-9.0% [48-75 mmol/mol]; 1-2 oral hypoglycaemic agents) were treated with intra-articular TA-ER (32 mg n = 18) or TAcs 40 mg (n = 15). Continuous glucose monitoring-measured glucose (CGMG) was assessed from 1 week pre-injection through 2 weeks postinjection. Endpoints included change in average daily CGMG from baseline (days -3 to -1) to days 1-3 postinjection (CGMGdays1-3) (primary) and percent time average hourly CGMG levels remained in prespecified glycaemic ranges. Results The change CGMGdays1-3 was significantly lower following TA-ER vs TAcs (14.7 vs 33.9 mg/dl, least-squares-mean-difference [95% CI]: -19.2 [-38.0, -0.4]; P = 0.0452). The percentage of time over days 1-3 that CGMG was in the target glycaemic range (70-180 mg/dl) was numerically greater for TA-ER (63.3%) vs TAcs (49.7%), and that CGMG was >180 mg/dl was lower for TA-ER (34.5%) vs TAcs (49.9%). Non-glycaemic adverse events were mild and comparable between groups. Conclusion TA-ER may enable intra-articular corticosteroid treatment with minimal blood glucose disruption in patients with knee osteoarthritis and type 2 diabetes mellitus. Trial registration ClinicalTrials.gov, https://clinicaltrials.gov, NCT02762370.

Background: Intra-articular corticosteroids relieve osteoarthritis pain, but rapid systemic absorption limits efficacy. FX006, a novel, microsphere-based, extended-release triamcinolone acetonide (TA) formulation, prolongs TA joint residence and reduces systemic exposure compared with standard TA crystalline suspension (TAcs). We assessed symptomatic benefits and safety of FX006 compared with saline-solution placebo and TAcs. Methods: In this Phase-3, multicenter, double-blinded, 24-week study, adults ≥40 years of age with knee osteoarthritis (Kellgren-Lawrence grade 2 or 3) and average-daily-pain (ADP)-intensity scores of ≥5 and ≤9 (0 to 10 numeric rating scale) were centrally randomized (1:1:1) to a single intra-articular injection of FX006 (32 mg), saline-solution placebo, or TAcs (40 mg). The primary end point was change from baseline to week 12 in weekly mean ADP-intensity scores for FX006 compared with saline-solution placebo. Secondary end points were area-under-effect (AUE) curves of the change in weekly mean ADP-intensity scores from baseline to week 12 for FX006 compared with saline-solution placebo, AUE curves of the change in weekly mean ADP-intensity scores from baseline to week 12 for FX006 compared with TAcs, change in weekly mean ADP-intensity scores from baseline to week 12 for FX006 compared with TAcs, and AUE curves of the change in weekly mean ADP-intensity scores from baseline to week 24 for FX006 compared with saline-solution placebo. Exploratory end points included week-12 changes in Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Knee Injury and Osteoarthritis Outcome Score Quality of Life (KOOS-QOL) subscale scores for FX006 compared with saline-solution placebo and TAcs. Adverse events were elicited at each inpatient visit. Results: The primary end point was met. Among 484 treated patients (n = 161 for FX006, n = 162 for saline-solution placebo, and n = 161 for TAcs), FX006 provided significant week-12 improvement in ADP intensity compared with that observed for saline-solution placebo (least-squares mean change from baseline: −3.12 versus −2.14; p < 0.0001) indicating ∼50% improvement. FX006 afforded improvements over saline-solution placebo for all secondary and exploratory end points (p < 0.05). Improvements in osteoarthritis pain were not significant for FX006 compared with TAcs using the ADP-based secondary measures. Exploratory analyses of WOMAC-A, B, and C and KOOS-QOL subscales favored FX006 (p ≤ 0.05). Adverse events were generally mild, occurring at similar frequencies across treatments. Conclusions: FX006 provided significant, clinically meaningful pain reduction compared with saline-solution placebo at week 12 (primary end point). Level of Evidence: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Objective: Intra-articular (IA) corticosteroids relieve osteoarthritis (OA) pain, but rapid absorption into systemic circulation may limit efficacy and produce untoward effects. We compared the pharmacokinetics of IA triamcinolone acetonide (TA) delivered as an extended-release, microsphere-based formulation (FX006) vs a crystalline suspension (TAcs) in knee OA patients. Method: This Phase 2 open-label study sequentially enrolled 81 patients who received a single IA injection of FX006 (5 mL, 32mg delivered dose, N=63) or TAcs (1 mL, 40mg, N=18). Synovial fluid (SF) aspiration was attempted in each patient at baseline and one post-IA-injection visit (FX006: Week1, Week6, Week12, Week16 or Week20; TAcs: Week6). Blood was collected at baseline and multiple post-injection times. TA concentrations (validated LC-MS/MS, geometric means), pharmacokinetics (non-compartmental analysis models), and adverse events (AEs) were assessed. Results: SF TA concentrations following FX006 were quantifiable through Week12 (pg/mL: 231,328.9 at Week1; 3590.0 at Week6; 290.6 at Week12); post-TAcs, only 2 of 8 patients had quantifiable SF TA at Week6 (7.7 pg/mL). Following FX006, plasma TA gradually increased to peak (836.4 pg/mL) over 24 hours and slowly declined to

Solar energy can be utilized to produce H2 via photocatalytic water splitting. One major drawback of the one-step approach is the co-production of H2 and O2 in the same reactor environment creating a potentially hazardous scenario. This obstacle can be avoided by utilizing CO2 as a flammability suppressant which is proven to be more effective than N2. In this case study, several membrane cascade designs were implemented to recover the H2 while maintaining compositions outside the flammability range. The optimizations are based on the use of commercially available composite polymer membranes from Membrane Technology and Research, Inc. (MTR) in the spiral wound architecture. Both the H2-selective membrane (Proteus™) and CO2-selective membrane (Polaris™) were explored in three layouts. The process optimization is solved by nonlinear programming. The aim of the study was to minimize the present value of all outgoing cash flow (no income) for the separation process and achieving 99% product (H2) purity. Optimization results showed that utilizing three membrane units of Proteus™ material with one recycle stream is the optimum layout over a wide range of recovery values. Incorporating the CO2-selective membrane (Polaris™) leads to more expensive process due to higher recycle flow rates to compensate for the low selectivity of this material. Overall, the best economic results for this process were obtained at 85% recovery rate with 99% product purity at a cost of 6.40 $/kg. Comparing to our previous study using a N2 diluent, higher purity product with lower specific cost can be achieved with CO2 diluent system but with slight decrease in recovery rate. As a final element to this study, comparative simulations were executed to demonstrate the potentially added value of using hollow fiber membranes versus spiral wound for this separation process.

Hydrogen can be produced by solar energy via photocatalytic water splitting. In the process, both hydrogen and oxygen are produced in the same environment. An inert gas (e.g. nitrogen) can be used in the reactor in order to eliminate the explosion hazards. In this case study, membrane cascade design was implemented to recover the hydrogen outside the flammability range using a commercial polyimide membrane from UBE® Industries (Japan). Two different ternary (H2, O2, N2) mixtures were investigated to recover and purify hydrogen outside the flammability range. Mixture (1) contains 4 mol-% hydrogen while Mixture (2) contains 6 mol-%. The process optimization is defined as a nonlinear programming (NLP). The aim of the objective function is to minimize the present value (PV) of all outgoing cash flows (no income) for the separation process with both flammability and recovery constraints to be satisfied. For a 100 kmol/h hydrogen feed basis, the results showed high investment and operating costs for Mixture (1) with a specific cost of 8.20 $/kg. The maximum recovery and purity that can be achieved, without further increase in cost, are 92% and 92.5%, respectively. Switching to Mixture (2) will result in a specific cost reduction of around 25% due to lower feed flow rates and higher molar concentrations of hydrogen. The maximum recovery is 90% with 95% purity. Beyond these values, the specific cost increase dramatically. This is the first fundamental process optimization considering safety issues as well as product recovery yield simultaneously from a tertiary gas mixture.

Summary We present an evaluation of shale dominated cap rocks relevant for Middle Jurassic sandstone reservoirs in the Central North Sea, based on well log data from the Norwegian Continental Shelf. Previously established indicators for brittleness and seal quality, E (Young's modulus) and ν (Poisson's ratio), are utilized in the analysis. Similar ductile to fairly ductile behaviour is found in different formations for five analysed wells, of which two are oil discoveries, one contains only oil shows, and two are dry. Cap rocks in the discovery wells are comparatively most brittle, compared to a published E–ν template. Uplift of ~500 m in one of the discovery wells is not found to have compromised the sealing capability. We also investigate how organic content influence an organic-rich shale interval in terms of cap rock properties by using kerogen substitution and comparing to the other more organic-lean shales, which does not support a direct correlation between TOC and ductility. Finally, we consider how observed properties of different shales relate to different mineralogical composition.

Understanding maturation of source rock is increasingly of interest in both conventional and unconventional plays. Shale diagenesis and hydrocarbon generation in shales has a direct relationship with the evolution of the mechanics of maturation. The Draupne Formation, a world class source rock, which stretches over a broad range of depths and maturity, provides the ideal candidate to study the interplay between maturation and geomechanical parameters. Wireline logs and Rock-Eval data from eight wells were used to analyse how seismic waves and rock strength interplays with the source rock shales. Results reveal that the Draupne shale behaves typically in terms of maturation, however the relationship between maturation and geomechanics counters the common trend for shale. There are a wide variety of factors that could impact the geomechanical trends, including but not limited to, lithology, mineralogy, pressure, temperature, fluid content, diagenesis, compaction, fracture density, and organic content. This paper identifies key relationships between geomechanical parameters and a number of these factors, while identifying further work that could be carried out in other areas. This further highlights the importance of in-depth play fairway analysis and presents questions that require answers for successful exploration and exploitation of hydrocarbon.

International audience; Objective: FX006 is a novel, microsphere-based, extended-release formulation of triamcinolone acetonide for intraarticular (IA) injection designed to maintain treatment concentration in the joint and provide prolonged analgesic benefits in patients with osteoarthritis (OA) of the knee. This study was undertaken to compare the analgesic benefits of 2 FX006 doses with saline placebo injection.Methods: In this phase IIb study, participants with knee OA (Kellgren/Lawrence grade 2–3) and average daily pain (ADP) intensity ≥5 to ≤9 (on a 0–10 Numerical Rating Scale) were randomized (1:1:1) to receive single IA injections of FX006 32 mg (n = 104) or 16 mg (n = 102) or saline placebo (n = 100). The primary end point was the least squares mean (LSM) change from baseline to week 12 in weekly mean ADP intensity scores for FX006 32 mg versus saline placebo.Results: The primary end point was not met (LSM change at week 12 −3.1 with FX006 32 mg versus −2.5 with saline placebo; LSM difference [95% confidence interval] −0.58 [−1.22, 0.07]) (P = 0.08). However, improvements in ADP intensity were significantly greater with FX006 32 mg than saline placebo at weeks 1–11 and week 13. Improvements in ADP intensity were significantly greater with FX006 16 mg versus saline placebo at weeks 1–9. A dose-response effect in duration of maximal analgesic effect was evident (13 weeks with 32 mg versus 9 weeks with 16 mg), with FX006 32 mg providing increased therapeutic benefit relative to FX006 16 mg. All treatments were well tolerated.Conclusion: Although the primary end point was not met, our findings indicate a prolonged reduction in symptoms with FX006 with an evident dose response and a safety profile similar to saline placebo.

We describe a new template-free method for the in situ formation of a monodispersed spherical mesoporous nanosilica-Torlon hollow-fiber composite. A thin layer of Torlon hollow fiber that comprises silica nanoparticles was created by the in situ extrusion of a tetraethyl orthosilicate/N-methyl-2-pyrrolidone solution in a sheath layer and a Torlon polymer dope in a core support layer. This new method can be integrated easily into current hollow-fiber composite fabrication processes. The hollow-fiber composites were then functionalized with 3-aminopropyltrimethoxy silane (APS) and evaluated for their CO2 -capture performance. The resulting APS-functionalized mesoporous silica nanoparticles/Torlon hollow fibers exhibited a high CO2 equilibrium capacity of 1.5 and 1.9 mmol g(-1) at 35 and 60 °C, respectively, which is significantly higher than values for fiber sorbents without nanoparticles reported previously.

The synthesis of aziridine-functionalized mesoporous silica membranes on polymeric hollow fibers is described, and their single-component CO2 and N2 permeation properties are investigated under both dry and humid conditions to elucidate the unusual permeation mechanisms observed in these membranes. Hollow fiber-supported mesoporous silica membranes are amine-functionalized with aziridine to yield hyperbranched aminopolymers within the membrane pores. The effects of the hyperbranched polymers in the mesopores on gas transport properties are investigated by single-component gas permeation measurements. The hyperbranched aminosilica membrane shows counterintuitive N2-selective (over CO2) permeation during operation under dry conditions. Further characterization of the permeation behavior reveals the effects of strong adsorption of CO2 under dry permeation conditions, leading to reduced CO2 diffusivity because of CO2-induced amine cross-linking in the mesopores. On the other hand, the hyperbranched aminosilic...

Oxygen transport in amorphous poly(ethylene furanoate) (PEF) was studied at various temperatures using complementary permeation and pressure-decay sorption techniques. A significant reduction in oxygen permeability of ∼11× was observed at 35 °C for PEF compared to poly(ethylene terephthalate) (PET), and is attributed primarily to reduction in chain segment mobility for PEF resulting from a hindrance of furan ring flipping. A custom-built high accuracy sorption system allowed determination of temperature-dependent so-called dual-mode parameters that have not been reported for oxygen in any polyester. Energetic parameters, i.e. the enthalpy of sorption and activation energies of diffusion and permeation, were measured for oxygen in PEF and discussed in the context of PET and related polyesters. The current work presents the first detailed study of penetrant transport in PEF, which demonstrates the impressive performance enhancements of PEF compared to PET.

High-surface-area gas separation membranes Membranes for gas separation require a combination of high surface area and selective transport pathways. Brown et al. present a potentially scalable route for making high-quality gas separation membranes in a high-surface-area configuration. Using two different solvents flowing in opposite directions, a metal-organic framework material was selectively deposited within hollow polymer fibers. The membranes showed high-performance separation capabilities when tested with mixtures of hydrocarbon gases. Science , this issue p. 72

Matrimid® hollow fiber membranes with silicone rubber (PDMS) calked fused nodular selective layers display much higher CO2/N2 selectivity as well as higher CO2 permeance than those with isotropic dense selective layers at 253.15 K. Two kinds of asymmetric hollow fiber membranes were successfully spun: fibers with fused nodular skins and fibers with truly dense skins. The skin morphologies were confirmed with SEM images. CO2/N2 mixed gas permeation characterization was carried out within the temperature range of 253.15 K to 308.15 K. Permeation results showed that, at 253.15 K, the nodular-skinned fibers displayed CO2/N2 selectivity of 90.5, and CO2 permeance of 63.3 GPU after standard PDMS calking; while the dense-skinned fibers displayed CO2/N2 selectivity of 52.5, and CO2 permeance of 16.6 GPU. The PDMS calking had negligible effect on the dense-skinned fibers, but it was necessary for the fused nodular-skinned fibers. A hypothesis regarding the introduction of Langmuir sorption sites and a local orientation of polymer chain segments is proposed to explain the better performance of the calked nodular-skinned fibers. This work provides a promising method for improved hollow fiber membranes for the removal of CO2 from flue gas.

The modification of cellulose acetate (CA) films via grafting of vinyltrimethoxysilane (VTMS) to −OH groups, with subsequent condensation of hydrolyzed methoxy groups on the silane to form a polyme...

The incorporation of accessible amine functionality in zeolitic imidazolate frameworks (ZIFs) is used to improve the adsorption selectivity for CO2/CH4 gas separation applications. Two synthetic approaches are described in this work to introduce functionality into the ZIF: (i) mixed-linker ZIF synthesis with 2-aminobenzimidazole as a substitution linker and (ii) postsynthetic modification of a mixed-linker ZIF with ethylenediamine. Using 2-aminobenzimidazole, a linker with a primary amine functional group, substitution of the ZIF-8 linker during synthesis allows for control over the adsorption properties while maintaining the ZIF-8 structure with up to nearly 50% substitution in the mixed-linker ZIF framework, producing a material with tunable pore size and amine functionality. Alternatively, postsynthetic modification of a mixed-linker ZIF containing an aldehyde functional group produces a ZIF material with a primary amine without detrimental loss of micropore volume by controlling the amount of function...

The authors would like to gratefully thank the King Abdullah University of Science and Technology (KAUST) for generously funding this work.

Using a process-guided approach, a new 6FDA-based polyimide — 6FDA–DAM:DABA(4:1) — has been developed in the form of hollow fiber membranes for CO 2 recovery from post-combustion flue gas streams. Dense film studies on this polymer reveal a CO 2 permeability of 224 Barrers at 40 °C at a CO 2 feed pressure of 10 psia. The dense films exhibit an ideal CO 2 /N 2 permselectivity of 20 at 40 °C, which permits their use in a two-step counter-flow/sweep membrane process. Dry-jet, wet-quench, non-solvent-induced phase inversion spinning was used to create defect-free hollow fibers from 6FDA–DAM:DABA(4:1). Membranes with defect-free skin layers, approximately 415 nm thick, were obtained with a pure CO 2 permeance of 520 GPU at 30 °C and an ideal CO 2 /N 2 permselectivity of 24. Mixed gas permeation and wet gas permeation are presented for the fibers. The CO 2 permeance in the fibers was reduced by approximately a factor of 2 in feeds with 80% humidity. As a proof-of-concept path forward to increase CO 2 flux, we incorporated microporous ZIF-8 fillers into 6FDA–DAM:DABA(4:1) dense films. Our 6FDA–DAM:DABA(4:1)/ZIF-8 dense film composites (20 wt% ZIF-8) had a CO 2 permeability of 550 Barrers and a CO 2 /N 2 selectivity of 19 at 35 °C. Good adhesion between the ZIF and the 6FDA–DAM:DABA(4:1) matrix was observed. CO 2 capture costs of $27/ton of CO 2 using the current, “non-optimized” membrane are estimated using a custom counterflow membrane model. Hollow fiber membrane modules were estimated to have order-of-magnitude reductions in system footprint relative to spiral-wound modules, thereby making them attractive in current space-constrained coal-fired power stations.

Headed for a membrane: Continuous, polycrystalline ZIF-90 membranes (picture, left) can be grown at 65 °C from methanolic precursor solutions on nanocrystal-seeded surfaces of poly(amide-imide) macroporous hollow fibers (right). The ZIF-90 membranes exhibit good separation properties for linear over cyclic hydrocarbons, as well as gas permeation selectivities higher than Knudsen values.

Organic-inorganic hybrid (mixed matrix) membranes can potentially extend the separation performance of traditional polymeric materials while maintaining processing convenience. Although many dense films studies have been reported, there have been few reported cases of these materials being successfully extended to asymmetric hollow fibers. In this work we report the first successful production of mixed matrix asymmetric hollow fiber membranes containing metal-organic-framework (MOF) ZIF-8 fillers. Specifically, we have incorporated ZIF-8 into a polyetherimide (Ultem((R)) 1000) matrix and produced dual-layer asymmetric hollow fiber membranes via the dry jet-wet quench method. The outer separating layer of these composite fibers contains 13 wt% (17 vol%) of ZIF-8 filler. These membranes have been tested over a range of temperatures and pressures for a variety of gas pairs. An increase in separation performance for the CO2/N-2 gas pairs was observed for both pure gas and mixed gas feeds. (C) 2012 Elsevier B.V. All rights reserved.

A fluorinated, 6FDA based polyamide–imide is investigated for the purification of CH 4 from CO 2 and H 2 S containing gas streams. Dense polymer films were thermally annealed and showed that increased annealing temperatures at constant annealing time caused transport behavior that does not resemble physical aging. Free volume increased after annealing at 200 °C for 24 h relative to annealing at 150 °C for the same time. CO 2 and CH 4 permeabilities and diffusivities did not decrease as a result of the higher annealing temperature, and in fact, were shown to increase slightly. A change to the intrinsic microstructure that cannot be described by simple, densification based physical aging is hypothesized to be the reason for this trend. Furthermore, annealing increased CO 2 induced plasticization resistance and a temperature of 200 °C was shown to have the greatest effect on plasticization suppression. Annealing at 200 °C for 24 h suppressed pure gas CO 2 plasticization up to 450 psia. Fluorescence spectroscopy revealed increased intramolecular charge transfer, which is presumably due to increased electron conjugation over the N-phenyl bond. Additionally, intermolecular charge transfer increased with thermal annealing, as inferred from fluorescence intensity measurements and XRD patterns. 50/50 CO 2 /CH 4 mixed gas permeation measurements reveal stable separation performance up to 1000 psia. Ternary mixed gas feeds containing toluene/CO 2 /CH 4 and H 2 S/CO 2 /CH 4 show antiplasticization, but more importantly, selectivity losses due to plasticization did not occur up to 900 psia of total feed pressure. These results show that the polyamide–imide family represents a promising class of separation materials for aggressive acid gas purifications.

Recently Tuiniers et al. (2010 ) proposed a method for CO 2 capture using cryogenically chilled packed beds with spherical packing that served as CO 2 de-sublimation sites. The research presented here extends that work using fibrous packing inside the cryogenic columns, which serve to increase the surface area-to-volume ratio of the column by up to an order of magnitude as well as significantly reducing the sweep gas pressure drop through the column. Two types of fiber were chosen to study the effect of surface area on the total amount of CO 2 captured within the column: hollow cellulose acetate fibers (325 μm OD/125 μm ID) with porous walls and monofilament nylon fibers (200 μm OD). The pre-chilled cellulose acetate fiber columns were able to capture 191.2 kg of CO 2 /m 3 of volume at a pressure drop of 3.9 psi/ft (81.0 kPa/m) despite very high superficial velocities of simulated flue gas (10% CO 2 in N 2 ) through the column (5,700 sccm, or 1.33 m/s). The nylon monofilament fibers were found to capture up to 185 kg of CO 2 /m 3 despite lower surface area than the porous cellulose acetate fibers. The total uptake as a function of surface area within the column was found to reach a maximum, which has been tentatively attributed to the limited amount of specific heat held within the column itself. While in actual operation a pure CO 2 sweep may be used to recover the solid CO 2 within the column, a N 2 sweep was used here to unequivocally demonstrate that the process can be used to generate a pure CO 2 product. By performing a two-stage sweep, CO 2 purities between 28 mol% (1.33 m/s sweep) and 99.5 mol% (4.4 cm/s sweep) were obtained. The findings of this study suggest that these low-cost fibrous materials have the opportunity to reduce the capital expenditures of a world-scale cryogenic CO 2 capture system as well as increase the total loading of CO 2 captured per chilling cycle while also reducing gas compression costs.

We report significantly enhanced propylene/propane (C 3 H 6 /C 3 H 8 ) selectivity in mixed matrix membranes fabricated using 6FDA-DAM polyimide and a zeolitic imidazolate framework (ZIF-8). Equilibrium isotherms and sorption kinetics of C 3 H 6 and C 3 H 8 at 35 °C were studied on a 200 nm commercially available ZIF-8 sample produced by BASF. Mixed matrix dense films were formed with 6FDA-DAM and 200 nm BASF ZIF-8 particles. SEM imaging showed generally good adhesion between the ZIF-8 and 6FDA-DAM without the need for surface-treating ZIF-8. Pure gas permeation showed significantly enhanced mixed matrix ZIF-8/6FDA-DAM membrane C 3 H 6 /C 3 H 8 separation performance over the pure 6FDA-DAM membrane performance. A C 3 H 6 permeability of 56.2 Barrer and C 3 H 6 /C 3 H 8 ideal selectivity of 31.0 was found in ZIF-8/6FDA-DAM mixed matrix membrane with 48.0 wt% ZIF-8 loading, which are 258% and 150% higher than the pure 6FDA-DAM membrane, respectively for permeability and selectivity. Permeation properties of C 3 H 6 and C 3 H 8 in ZIF-8 were back-calculated by the Maxwell model for composite permeability using pure gas permeation data, leading to a C 3 H 6 permeability of 277 Barrer and C 3 H 6 /C 3 H 8 selectivity of 122. Mixed gas permeation also verified that selectivity enhancements were achievable in mixed gas environment by ZIF-8.

Improvement in the efficiency of CO2 separation from flue gases is a high-priority research area to reduce the total energy cost of carbon capture and sequestration technologies in coal-fired power plants. Efficient CO2 removal from flue gases by adsorption systems requires the design of novel sorbents capable of capturing, concentrating, and recovering CO2 on a cost-effective basis. This paper describes the preparation of an aminosilane-functionalized cellulosic polymer sorbent with enhanced CO2 sorption capacity and promising performance for use in postcombustion carbon capture via rapid temperature-swing adsorption systems. The introduction of aminosilane functionalities onto the backbone of cellulose acetate was achieved by the anhydrous grafting of N-(2-aminoethyl)-3-aminoisobutyldimethylmethoxysilane. The dry sorption capacity of the modified cellulosic polymer reached 27 cc (STP) CO2/cc sorbent (1.01 mmol/g sorbent) at 1 atm and 39 cc (STP) CO2/cc sorbent (1.46 mmol/g sorbent) at 5 atm and 308 K. T...

Aluminum hydride is a material that is well known for its high gravimetric and volumetric hydrogen densities and thus is an attractive hydrogen storage compound; however, it is thermodynamically unstable at room temperature requiring 7 × 103 bar pressure to reform the hydride from Al and H2. An alternate method of AlH3 formation is possible using a reversible organometallic synthesis employing catalyzed Al powder, H2, and quinuclidine, or another tertiary amine, as an intermediate step. Additionally, many tertiary amines are known to react directly with AlH3 to form adducts. Previous work indicates that two polymorphs of quinuclidine alane exist, formed using an irreversible process that requires expensive starting materials (e.g. LiAlH4). The conditions of reversible adduct formation are detailed herein, as well as an analysis of quinuclidine alane by Fourier transform infrared spectroscopy and X-ray diffraction.

Thin, continuous, mesoporous silica membranes are formed on polymeric hollow fibers via liquid-phase coating at roomtemperature and aging with tetraethylorthosilicate (TEOS) vapor at 100 °C. After liquid extraction of the surfactant template and mesopore infiltration with an aminoalkyloctasilsesquioxane, the membrane displays CO2-selective gas permeation properties.

Mixed matrix membranes (MMMs) with low particle loadings have been shown to improve the properties of pure polymers for many gas separations. Comparatively few reports have been made for high particle loading (≥50 vol.%) MMMs. In this work, CO2–CH4 feeds were used to study the potential of 50 vol.% zeolite 4A-poly(vinyl acetate) (PVAc) MMMs for natural gas separations. A low CO2 partial pressure mixed feed probed MMM performance below the plasticization pressure of PVAc and a high CO2 partial pressure mixed feed probed MMM performance at industrially relevant conditions above the plasticization pressure. Under both mixed feed conditions at 35 °C, substantial improvements in overall separation performance were observed. At low CO2 partial pressures, CO2 permeability roughly doubled with a nearly 50% increase in selectivity versus pure PVAc under the same conditions. For the high CO2 partial pressure feed, CO2 permeability remained effectively unchanged with a 63% increase in selectivity versus pure PVAc. Surprisingly, the performance of these PVAc based MMMs approached the properties of current “upper bound” polymers. Overall, this work shows that significantly improved performance MMMs can be made with traditional techniques from a low cost, low performance polymer without costly adhesion promoters.