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A model for the physical description of water transport through steady-state permeation and dynamic sorption within perfluoro-sulfonic acid (PFSA) membranes has been developed. A broad experimental campaign is conducted on several membranes, belonging to Aquivion class, varying both in thickness and equivalent weight (EW). The experimental data have been used to calibrate and validate water transport model and to find correlations for mass-transfer properties in low-EW PFSA membranes that describe consistently both water vapor permeation and sorption. It has been possible to identify individual contributions to mass transport resistance and to determine the optimal configuration and materials of a full-scale counter-flow membrane humidifier under a set of specific operating conditions.

Anion-exchange membranes (AEMs) are of growing interest for electrochemical devices such as fuel cells and electrolyzers because the alkaline medium allows avoiding the use of platinum and platinum-group metals as the electrocatalysts. Perfluorinated polymers are a good starting point to prepare AEMs because of their chemical stability and potential high conductivity resulting from the coexistence of hydrophobic main chains and flexible hydrophilic side chains. Here, we report a facile and simple chemical modification of Aquivion® performed in aqueous environment. We obtained a chemically stable membrane with ionic conductivity exceeding 2.5×10−2 S cm−1 at 80 °C and 100 RH% that was used in a polymer fuel cell.

The solvent-free hydrogenation reaction of acetone over bifunctional heterogeneous catalysts, comprising cross-linked perfluorosulfonic acid (PFSA) resins and supported Pd nanoparticles, was investigated in the liquid phase under batch conditions. A systematic study was performed by analyzing separately the effect of the main reaction parameters on the reaction outputs. Acetone conversion, selectivity and productivity to methyl isobutyl ketone (MIBK) were measured as a function of the reaction temperature, the amount of catalyst, the Pd loading, the H2 pressure, the reaction time and the cross-linkage of the polymeric support. Reproducible trends were observed that could be explained in terms of properties of the catalyst, conversion path and kinetics. Best compromise results between selectivity (92 %) and productivity (37.0 mmolMIBK gcat−1 h-1) at 19.7 % acetone conversion were obtained for the 0.26Pd@X-link-08-PW79 catalyst, based on 0.8 % cross-linked PFSA support and 0.26 % wt Pd content.

In this work, Aquivion PFSA resin was shown to be an interesting alternative as a heterogenous catalyst for the continuous gas phase reaction of ethanol dehydration in mild conditions, thanks to its high thermal stability and superacid character. This material was confirmed to have a high thermal stability up to 300 °C, after which the desulphonation process began. Under optimised reaction conditions, the Aquivion catalyst showed a conversion of over 90 % ethanol as well as a selectivity to ethylene. The only detected by-product was diethyl ether, the formation of which was facilitated by low temperature. The dehydration activity was shown to depend on the number of acid sites and material shaping. Fluorescence microscopy, used to study the penetration of different alcohols into the shaped Aquivion, indicated the high polarity of ethanol, enabling the permeation into the pellet structure, thus facilitating the use of the -SO3H that is available on the resin, despite its very low surface area. The catalyst’s durability was proven by a stable operation for 14 h on-stream at 150 °C, without a significant evidence of coke deposition.

International audience; Proton Exchange Membrane Fuel Cells (PEM-FC) are considered an alternative to the internal combustion engine for transportation. Despite the existence of relevant demonstrations and few commercial fleets, there are still a series of issues such as the durability of the materials and the cost of platinum which limit a wider application in this field. To this regard, better utilization and consequently loading reduction of Pt in electrodes is of outstanding importance. Herein we report the synthesis, characterization and application of an ionomer in the cathode catalyst layer; thanks to its higher oxygen permeability the quantity of Pt may be minimized. This ionomer is a modification of commercial Aquivion ® PFSA obtained by incorporation of a third monomer (2,2,4-trifluoro-5-trifluoromethoxy-1,3-dioxole, MDO). Results on cast membrane demonstrate a 20% higher oxygen permeability of the new ionomer compared to Aquivion PFSA E87-05S and Nafion NR212 at 100% RH. Furthermore, an improvement of the performance of a PEM-FC in automotive conditions (RH=40-70%) is obtained with the assembly where this ionomer is used as cathode binder. In particular polarization curve at 70% RH shows improvement of 20% of power density peak and electrochemical impedance confirms higher oxygen permeability due to lower mass transport resistance than Aquivion.

The function of catalytic layers in fuel cells and electrolyzers depends on the properties of the ionically conductive phase, which are most commonly perfluorinated ionomers based on Nafion and Aquivion. An analysis by atomic force microscopy reveals that the ultrathin ionomer films around Pt/C agglomerates have a thickness distribution ranging from 3.5 nm to 20 nm. Their conductivity and gas permeation properties determine the fuel cell performance to a large extend. For electrodes in Aquivion-based membrane-electrode-assemblies operation-induced structure changes were investigated by means of material- and conductivity-sensitive atomic force microscopy, infrared spectroscopy and electron-dispersive X-ray analysis. The observed thinning of the ultrathin ionomer films was mainly caused by polymer degradation deduced from reduced swelling after long-time operation and a significant loss of ionomer with operation time detected by infrared spectroscopy. From the linear thickness increase of the ultrathin films with rising humidity, a mainly layered structure of the ionomer was deduced. An influence of thickness of such ultrathin ionomer films on fuel cell lifetime was found by analysis of differently prepared membrane-electrode-assemblies, where a linear increase of irreversible degradation rate with ionomer film thickness in the electrodes of unused membrane-electrode-assemblies was found.

The catalytic performance of Aquivion PFSA, a solid superacid, was investigated in the catalytic glycosylation of glucose with fatty alcohols. Four main criteria were considered to evaluate the catalytic performance of Aquivion PFSA: (1) the selectivity of the reaction, (2) the turnover frequency, (3) the reactor productivity, and (4) the catalyst stability/recycling. To shed light on the catalytic performance of Aquivion PFSA, it was systematically compared to H2SO4, which is industrially employed in such reactions. We discovered that Aquivion PFSA surpassed the catalytic performance of H2SO4 in terms of activity, selectivity, and reactor productivity. In particular, Aquivion PFSA selectively converted glucose to alkyl polyglucosides (DP = 1.2) with 85% yield, which corresponded to a reactor productivity as high as 477 kg/(m3 h). Conversely to H2SO4, Aquivion PFSA was also capable of selectively producing alkyl polyglucosides directly from glucose syrup, a cheap source of glucose. This result was ascribe...

In this paper, we present a straightforward synthesis of bimetallic radical scavengers supported onto silica and an evaluation of their effectiveness to increasing the lifetime of Aquivion® PFSA membranes. Such scavengers comprise cerium (Ce) and chromium (Cr) and were incorporated in e-PTFE reinforced thin membranes through suspension in water-based Aquivion® PFSA dispersion. The bimetallic samples were physico-chemically characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and Energy Dispersive X-ray (EDX) analyses and compared to the monometallic Ce and Cr scavengers prepared in the same way. The membranes containing the mono- or bi-metallic scavengers were electrochemically investigated in terms of polarization behavior, cell resistance and durability. The MEA based on monometallic Ce-based scavenger showed the largest durability (7-time more than a reference MEA). The bimetallic scavenger appears also very promising. However, a proper optimization of the composition is required for its application in highly durable composite Aquivion® membrane.

A quantitative in situ investigation of the structure of the catalytic layer of polymer electrolyte membrane fuel cells using material-sensitive and conductive atomic force microscopy is reported. The distribution and size of the ionomer phase at the surface of the catalytic layer is retrieved from adhesion force mappings, measured at high humidity and up to 75 °C. The average ionomer layer thickness varies between 7 and 13 nm for three differently prepared samples, as concluded from the histograms. Evidence of a lamellar structure of the thinner ionomer layers is presented. A significant thinning of the ionomer layers after long-term fuel cell operation is observed.

The Hardware in the Loop simulation is an useful instrument to simulate complex mechanical systems in which the subject of the test is an hardware component. The results of the simulation, closer to the real behavior of the system, are the main advantage of this approach. This application is often used during the design process to test components of a complex mechanical system before the development of the prototype (e.g. embedded systems). The literature examples show, in general, mathematical model finalized to the application. The objective of this work is focused on the development of a generic Multi-Body software for HIL applications. Some simulations examples, the dynamic of a slider-crank and of a McPherson suspension, are presented at the end of the paper.Copyright © 2010 by ASME

The reactivity of carboxy-terminated poly(1-vinylpyrrolidin-2-one) (PVP-COOH) 40-mers 1 with various small bi-functionalized molecules has been investigated. A number of new differently functionalized PVP 3–11 have been successfully obtained demonstrating that the presence of the bulky PVP chain did not hamper the reactivity of the carboxy group. This would imply that in solution the carboxyl group is not buried inside the coil, but well exposed to the solvent, as further confirmed by a molecular dynamics conformational study. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1683–1698, 2008

Membrane-electrode assemblies based on chemically stabilised short-side-chain proton exchange Aquivion® membranes, prepared by extrusion or recast methods, have been investigated for operation at high current density (3–4 A cm−2) in water electrolysis cells. A thickness of 90 μm was selected for these perfluorosulfonic acid membranes in order to provide proper resilience to hydrogen crossover under differential pressure operation while allowing operation at high currents. The membranes showed proper mechanical strength for high-pressure operation and suitable conductivity to reduce ohmic losses at high current densities. Both membranes showed excellent performance in electrolysis cells by achieving a voltage efficiency better than 85% and 80% (1.85 V) at 3 and 4 A cm−2, respectively, in polarisation curves at 90 °C. A smaller surface roughness was observed from atomic force microscopy for the recast membrane compared to the extruded one. This may affect the intimate contact between the ionic clusters of the membrane and the catalyst agglomerate at the interface producing a catalytic enhancement in the activation region of the polarisation curves in the case of the recast membrane. At high cell voltages, the polarisation resistance was instead slightly lower for the cell based on the extruded membrane. Interestingly, the different characteristics of the membrane-electrodes interface produced lower recoverable losses in durability studies for the recast membrane-based electrolyser allowing stable operation at both 3 and 4 A cm−2. Hydrogen crossover analysis at a differential pressure of 20 bar showed low gas permeation through both membranes allowing for a wide load range (15–100%) and high faradaic efficiency >99% at practical current densities (1–4 A cm−2).