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Low-temperature electrolysis by using polymer electrolyte membranes (PEM) can play animportant role in hydrogen energy transition. This work presents a study on the performance of aproton exchange membrane in the water electrolysis process at room temperature and atmosphericpressure. In the perspective of applications that need a device with small volume and low weight, aminiaturized electrolysis cell with a 36 cm2active area of PEM over a total surface area of 76 cm2of thedevice was used. H2and O2production rates, electrical power, energy efficiency, Faradaic efficiencyand polarization curves were determined for all experiments. The effects of different parameters suchas clamping pressure and materials of the electrodes on polarization phenomena were studied. ThePEM used was a catalyst-coated membrane (Ir-Pt-Nafion(TM)117 CCM). The maximum H2productionwas about 0.02 g min-1with a current density of 1.1 A cm-2and a current power about 280 W.Clamping pressure and the type of electrode materials strongly influence the activation and ohmicpolarization phenomena. High clamping pressure and electrodes in titanium compared to carbonelectrodes improve the cell performance, and this results in lower ohmic and activation resistances (PDF) Green H2 Production by Water Electrolysis Using Cation Exchange Membrane: Insights on Activation and Ohmic Polarization Phenomena.

Polymer-based membranes can be used for energy efficient gas separations. Successful exploitation of new materials requires accurate knowledge of the transport properties of all gases of interest. An open source database of such data is of significant benefit to the research community. The Membrane Society of Australasia (https://membrane-australasia.org/) hosts a database for experimentally measured and reported polymer gas permeabilities. However, the database is incomplete, limiting its potential use as a research tool. Here, missing values in the database were filled using machine learning (ML). The ML model was validated against gas permeability measurements that were not recorded in the database. Through imputing the missing data, it is possible to re-analyse historical polymers and look for potential “missed” candidates with promising gas selectivity. In addition, for systems with limited experimental data, ML using sparse features was performed, and we suggest that once the permeability of CO2 and/or O2 for a polymer has been measured, most other gas permeabilities and selectivities, including those for CO2/CH4 and CO2/N2, can be quantitatively estimated. This early insight into the gas permeability of a new system can be used at an initial stage of experimental measurements to rapidly identify polymer membranes worth further investigation.

Polymers of intrinsic microporosity (PIMs), such as the archetypal spirobisindane-based PIM-1, are among the most promising new materials for making gas separation membranes with high permeance for potential use in high-throughput applications. Here it is shown that ultrapermeable PIMs can be prepared by fusing rigid and bulky triptycene (Trip) to the spirobisindane (SBI) unit. PIM-SBI-Trip and its copolymer with PIM-1 (PIM-1/SBI-Trip) are both ultrapermeable after methanol treatment (PCO2 > 20 000 Barrer). Old films, although less permeable, are more selective and therefore provide data that are close to the recently redefined Robeson upper bounds for the important CO2/CH4, CO2/N2, and O2/N2 gas pairs. Temperature-dependent permeation measurements and analysis of the entropic and energetic contributions of the gas transport parameters show that the enhanced performance of these polymers is governed by strong size-sieving character, mainly due to the energetic term of the diffusivity, and related to their high rigidity. Both polymers show a relatively weak pressure-dependence in mixed gas permeability experiments up to 6 bar, suggesting a potential use for CO2 capture from flue gas or for the upgrading of biogas.

This manuscript describes the gas separation performance of PIM-2, a partially fluorinated linear copolymer synthesized from 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethylspirobisindane (TTSBI) and decafluorobiphenyl (DFBP). As one of the early members of the family of polymers of intrinsic microporosity, it had never been tested as a gas separation membrane because of insufficient mechanical resistance. This has been solved only recently, allowing the preparation of robust self-standing films. Molecular modelling studies demonstrated a high fractional free volume (34%) and an elevated surface area (642 m2 g-1), and the latter is in good agreement with experimental BET results. Pure gas permeabilities measured on a fixed-volume time-lag instrument at 1 bar compare well with the results of mixed separation tests on a variable volume setup from 1-6 bar(a). Molecular modelling and independent sorption measurements on a gravimetric sorption balance both show strong dual-mode sorption behaviour, especially for CO2 and to a lesser extent for CH4. Temperature-dependent pure gas permeation measurements show typical Arrhenius behaviour, with a clear increase in the activation energy for diffusion with the increasing molecular size of the gas, indicating high size-selectivity. This is in agreement with the highly rigid PIM structure, determined by AFM force spectroscopy measurements. The dual-mode behaviour results in a moderate pressure dependence of the CO2 permeability and the CO2/N2 and CO2/CH4 selectivity, all slightly decreasing with increasing pressure. The presence of humidity in the gas stream has a remarkable small effect on the membrane performance, which is probably due to the high fluorine content and the consequently low water vapour solubility in the polymer, as confirmed by gravimetric sorption measurements. The manuscript describes an extensive study on the structure-property relationships in PIM-2. © 2019 Elsevier B.V. European Commission, EC Grantová Agentura Ceské Republiky, GA Ä?R: 18-05484S --Research on biogas upgrading presented in this work was supported by EU structural funding in the frame of Operational Programme Research, Development and Education, project No. CZ.02.1.01./0.0/0.0/17_049/0008419 “COOPERATION”. This work was further supported by the CNR-CAS bilateral agreement 2016–2018 “Innovative polymeric membranes for pervaporation and advanced gas and vapour separations” and by the Czech Science Foundation (grant no. 18-05484S ). Appendix A

The growing interest towards the hydrogen utilization as energy carrier placed a high demand on hydrogen permeable membranes as compact devices for hydrogen separation and purification. Many studies in this scientific field demonstrated that the composite Pd-based membranes are particularly effective for the aforementioned purposes, particularly if compared to the utilization of self-supported Pd-based membranes for their high cost and mechanical limitations. As a case study, a composite membrane based on a thin Pd-Au (8 μm of metallic layer and 12 wt% of Au) supported on α-Al2O3 substrate was produced by electroless plating deposition. Permeation tests were performed with pure gases (H2, N2, CO2, CH4) by varying the temperature between 300 °C and 400 °C and the feed pressure from 150 to 350 kPa. The exponential factor (n-value) in the equation describing the relationship between the hydrogen flux permeating through the membrane and its driving force was analyzed as a function of temperature and pressure variation. An apparent activation energy of 11 kJ/mol has been reached and it is comparable to other data present in the open literature. A H2/N2 ideal selectivity of around 500 was reached at 400 °C and 50 kPa of transmembrane pressure and it remained stable up to 600 h under operation. The presence of defects on the metallic layer has affected the membrane performance in terms of H2 perm-selectivity as testified by the post-mortem analysis on the exhausted membrane.