scholarly journals Hydrogen Separation and Purification from Various Gas Mixtures by Means of Electrochemical Membrane Technology in the Temperature Range 100–160 °C

Membranes ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 282
Author(s):  
Leandri Vermaak ◽  
Hein W. J. P. Neomagus ◽  
Dmitri G. Bessarabov
Keyword(s):  
Hydrogen Permeability ◽  
Gas Mixtures ◽  
Open Circuit ◽  
Hydrogen Separation ◽  
Proton Exchange ◽  
Limiting Current ◽  
Separation Performance ◽  
Separation And Purification ◽  
Irreversible Damage ◽  
Temperature Range

This paper reports on an experimental evaluation of the hydrogen separation performance in a proton exchange membrane system with Pt-Co/C as the anode electrocatalyst. The recovery of hydrogen from H2/CO2, H2/CH4, and H2/NH3 gas mixtures were determined in the temperature range of 100–160 °C. The effects of both the impurity concentration and cell temperature on the separation performance of the cell and membrane were further examined. The electrochemical properties and performance of the cell were determined by means of polarization curves, limiting current density, open-circuit voltage, hydrogen permeability, hydrogen selectivity, hydrogen purity, and cell efficiencies (current, voltage, and power efficiencies) as performance parameters. High purity hydrogen (>99.9%) was obtained from a low purity feed (20% H2) after hydrogen was separated from H2/CH4 mixtures. Hydrogen purities of 98–99.5% and 96–99.5% were achieved for 10% and 50% CO2 in the feed, respectively. Moreover, the use of proton exchange membranes for electrochemical hydrogen separation was unsuccessful in separating hydrogen-rich streams containing NH3; the membrane underwent irreversible damage.

Thermal Degradation Behavior of Hydrogen Permeability of Pd-Coated V-Alloy Membrane for Hydrogen Separation and Purification

2021 ◽  
Vol 1016 ◽  
pp. 1710-1714
Author(s):  
Hiroshi Yukawa ◽  
Tomonori Nambu ◽  
Yoshihisa Matsumoto
Keyword(s):  
Thermal Activation ◽  
Hydrogen Permeability ◽  
Testing Temperature ◽  
Hydrogen Separation ◽  
Activation Process ◽  
Degradation Behavior ◽  
Separation And Purification ◽  
Accelerated Degradation ◽  
Thermal Degradation Behavior ◽  
Thermal Activation Process

A series of accelerated degradation experiments at high temperatures have been performed for Pd-coated V-10 mol% Fe alloy membranes in order to investigate the degradation behavior of hydrogen permeability. The degradation of the membrane becomes severer with increasing testing temperature. The temperature dependence of the 20% degradation rate almost obeys the Arrhenius relationship, suggesting that the degradation phenomenon occurs by a kind of thermal activation process. It is found that the addition of a small amount of W into Pd overlayer improves the durability of the membrane significantly.

Design and Development of Nb-W-Mo Alloy Membrane for Hydrogen Separation and Purification

2013 ◽  
Vol 333 ◽  
pp. 61-71 ◽  
Author(s):  
Hiroshi Yukawa ◽  
T. Nambu ◽  
Yoshihisa Matsumoto
Keyword(s):  
Hydrogen Embrittlement ◽  
Hydrogen Diffusion ◽  
Hydrogen Permeability ◽  
Hydrogen Separation ◽  
Solution Phase ◽  
Solid Solution Phase ◽  
Separation And Purification ◽  
Hydrogen Diffusivity ◽  
Permeable Membrane ◽  
Alloying Effects

The concept for alloy design of Nbbased hydrogen permeable membrane is applied to NbWMo ternary system. The alloying effects of tungsten and molybdenum on the solubility of hydrogen, the resistance to hydrogen embrittlement, the hydrogen permeability and diffusivity are investigated in a fundamental manner. It is found that the addition of tungsten and molybdenum into niobium decreases the hydrogen solubility. As a result, the resistance to hydrogen embrittlement improves and higher hydrogen pressures can be applied to the NbWMo alloy membrane. It is shown that the designed Nb5mol%W5mol%Mo alloy membrane with single solid solution phase exhibits excellent hydrogen permeability together with strong resistance to hydrogen embrittlement. In addition, it is found that the alloying of tungsten and molybdenum with niobium enhances the hydrogen diffusivity. In fact, the activation energy for hydrogen diffusion decreases in the order, pure Nb > Nb5mol%W > Nb5mol%W5mol%Mo.

Performance decay of proton-exchange membrane fuel cells under open circuit conditions induced by membrane decomposition

2009 ◽  
Vol 187 (2) ◽  
pp. 324-331 ◽  
Author(s):  
Seiho Sugawara ◽  
Takao Maruyama ◽  
Yoshiki Nagahara ◽  
Shyam S. Kocha ◽  
Kazuhiko Shinohra ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Proton Exchange Membrane ◽  
Open Circuit ◽  
Proton Exchange ◽  
Exchange Membrane

A Model of a High-Temperature Direct Methanol Fuel Cell

2013 ◽  
Vol 10 (5) ◽  
Author(s):  
K. Scott ◽  
S. Pilditch ◽  
M. Mamlouk
Keyword(s):  
Fuel Cell ◽  
Direct Methanol Fuel Cell ◽  
Proton Exchange Membrane ◽  
Open Circuit ◽  
Proton Exchange ◽  
Cell Performance ◽  
Effect Of Temperature ◽  
Fuel Cell Performance ◽  
Direct Methanol ◽  
Methanol Fuel Cell

A steady-state, isothermal, one-dimensional model of a direct methanol proton exchange membrane fuel cell (PEMFC), with a polybenzimidazole (PBI) membrane, was developed. The electrode kinetics were represented by the Butler–Volmer equation, mass transport was described by the multicomponent Stefan–Maxwell equations and Darcy's law, and the ionic and electronic resistances described by Ohm's law. The model incorporated the effects of temperature and pressure on the open circuit potential, the exchange current density, and diffusion coefficients, together with the effect of water transport across the membrane on the conductivity of the PBI membrane. The influence of methanol crossover on the cathode polarization is included in the model. The polarization curves predicted by the model were validated against experimental data for a direct methanol fuel cell (DMFC) operating in the temperature range of 125–175 °C. There was good agreement between experimental and model data for the effect of temperature and oxygen/air pressure on cell performance. The fuel cell performance was relatively poor, at only 16 mW cm−2 peak power density using low concentrations of methanol in the vapor phase.

From –20 to 200 °C: Fuel Cells with Broad Operational Flexibility Enabled by Intrinsically Ultramicroporous Membranes

2021 ◽  
Author(s):  
Hongying Tang ◽  
Kang Geng ◽  
Lei Wu ◽  
Junjie Liu ◽  
Zhiquan Chen ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Proton Exchange Membrane ◽  
Proton Exchange ◽  
Operational Flexibility ◽  
Full Spectrum ◽  
Innovative Design ◽  
Temperature Range ◽  
Temperature Conditions ◽  
Start Up ◽  
Exchange Membrane

Abstract Conventional proton exchange membrane fuel cells (PEMFCs) operate at a narrow temperature range, either under low temperature conditions (80‒90°C) using fully-humidified perfluorosulfonic acid (Nafion®) membranes or under non-humidified high temperature conditions (140‒180°C) using phosphoric acid (PA)-doped membranes to avoid water condensation-induced PA leaching. To allow wide operational flexibility over the full spectrum of temperature and humidity ranges, we present an innovative design strategy by using PA-doped intrinsically ultramicroporous membranes constructed from rigid and contorted high free volume polymers. The membranes with an average ultramicropore radius of 3.3 Å showed a significant siphoning effect as confirmed by the delocalization of PA in 31P NMR, thus allowing high retention of PA even under highly humidified conditions and presenting more than three orders of magnitude higher proton conductivity retention than conventional dense PA-doped polybenzimidazole membranes (PBI/PA). The resulting PEMFCs display impressive performance over a much broader temperature range from − 20 to 200°C and can accomplish over 100 start-up/shut-down cycles even at − 20°C. The broad operational flexibility rendered from the high PA-retention can ultimately simplify heat and water management and thereby reduce PEMFC costs.

Pure Ni and Pd-Ni Alloy Membranes Prepared by Electroless Plating for Hydrogen Separation

2011 ◽  
Vol 179-180 ◽  
pp. 1309-1313 ◽  
Author(s):  
Xiao Liang Zhang ◽  
Xu Feng Xie ◽  
Yan Huang
Keyword(s):  
Electroless Plating ◽  
Hydrogen Permeation ◽  
Hydrogen Permeability ◽  
Composite Membranes ◽  
Hydrogen Separation ◽  
High Hydrogen ◽  
Ni Alloy ◽  
Plating Method ◽  
Fcc Phase ◽  
The Ideal

Pd-based composite membranes are the attractive membrane materials for hydrogen separation due to their high hydrogen permeability and infinite permselectivity. Thin pure Ni and Pd-Ni alloy membranes with high hydrogen permeation were prepared by the electroless plating method. It is difficult to prepare the dense pure Ni membranes with 1-2 μm thickness for hydrogen separation. However, Pd-Ni alloy membranes with several micrometers thickness showed good permeation performance. Hydrogen permeance of the Pd95Ni5 alloy membrane with fcc phase up to 3.1×10-6 mol/m2 s Pa and the ideal permselectivity over 600 were obtained at 773 K.

Ignition Studies of C1-C7 Natural Gas Blends At Gas-Turbine Relevant Conditions

2021 ◽  
Author(s):  
Amrit Sahu ◽  
A.A.E.S Mohamed ◽  
Snehashish Panigrahy ◽  
Gilles Bourque ◽  
Henry Curran
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Gas Mixtures ◽  
Rapid Compression Machine ◽  
Temperature Range ◽  
Auto Ignition ◽  
Wide Range ◽  
Model Predictions ◽  
Detailed Kinetic Model ◽  
Sensitization Effect

Abstract New ignition delay time measurements (IDT) of natural gas mixtures enriched with small amounts of n-hexane and n-heptane were performed in a rapid compression machine to interpret the sensitization effect of heavier hydrocarbons on auto-ignition at gas-turbine relevant conditions. The experimental data of natural gas mixtures containing alkanes from methane to n-heptane were carried out over a wide range of temperatures (840-1050 K), pressures (20-30 bar), and equivalence ratios (f = 0.5 and 1.5). The experiments were complemented with numerical simulations using a detailed kinetic model developed to investigate the effect of n-hexane and n-heptane additions. Model predictions show that the addition of even small amounts (1-2%) of n-hexane and n-heptane can lead to an increase in reactivity by ~40-60 ms at a temperature of 700 K. The IDTs of these mixtures decrease rapidly with an increase in the concentration of up to 7.5% but becomes almost independent of the C6/C7 concentration >10%. This sensitization effect of C6 and C7 is also found to be more pronounced in the temperature range 700-900 K compared to that at higher temperatures (>900 K). The reason is attributed to the dependence of IDT primarily on H2O2(+M)??H+?H (+M) at higher temperatures while the fuel-dependent reactions such as H-atom abstraction, RO2 dissociation, or Q OOH+O2 reactions are less important compared to the temperature range 700-900 K, where they are very important.

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