Dense Carbide/Metal Composite Membranes for Hydrogen Separations Without Platinum Group Metals

Gade, Sabina K.; Chmelka, Sara J.; Parks, Sterling; Way, J. Douglas; Wolden, Colin A.

doi:10.1002/adma.201100931

Cited by 38 publications

(39 citation statements)

References 19 publications

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“…Our previous work examined 60 nm Mo 2 C/50 micron V composites, and in that case the exponent that provided the best fit to Eq. (1) was found to be 0.8 < n < 1 [64], suggesting that H 2 dissociation (step 2) was a primary factor limiting rate. Steps 3 & 5 correspond to hydrogen transport through the carbide catalyst layers, which will be identical since the membranes considered in this work are symmetric.…”

Section: Permeation Modelmentioning

confidence: 96%

“…Steps 3 & 5 correspond to hydrogen transport through the carbide catalyst layers, which will be identical since the membranes considered in this work are symmetric. Previous TEM imaging revealed that the carbide layers are quite dense [64], suggesting that although thin they may impede hydrogen transport. Molybdenum carbide is not intrinsically hydrogen permeable, however atomic hydrogen may readily diffuse on its surface [65].…”

Section: Permeation Modelmentioning

confidence: 99%

“…A low-cost hydrogen dissociation layer that can operate at higher temperatures than a metallic catalyst would therefore be both a novel discovery and potentially a great spur to development of BCC-phase dense metal membranes. In this research project, we have shown that metal carbides can be sputtered on V foil membranes and these composite structures perform very well as high temperature hydrogen membranes [5,6]. The influence of temperature on the pure gas hydrogen permeability of selected metals.…”

Section: Co Tolerance Yes Yesmentioning

confidence: 99%

“…These carbides, and analogous nitride and sulfides, have been pursued as substitutes for precious-metal catalysts in reactions requiring hydrogen dissociation, such as hydroprocessing [65], methanol reforming [66] or water-gas shift reactors [67]. In our previous work it was shown that Mo 2 C/V membranes were stable, with no loss of permeance or evidence of interdiffusion or alloy formation during extended operation at high temperature (≥ 600 °C) [64]. In this work we explore the mechanism and identify rate-limiting steps for hydrogen transport in these membranes.…”

Section: Introductionmentioning

confidence: 99%

“…Recently we introduced Mo 2 C-coated vanadium composites as an example of a new class of metallic membranes for hydrogen separations [64]. These membranes displayed both high flux and perfect selectivity at elevated temperature.…”

Section: Introductionmentioning

confidence: 99%

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Nanoporous, Metal Carbide, Surface Diffusion Membranes for High Temperature Hydrogen Separations

Way¹,

Wolden²

2013

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Colorado School of Mines (CSM) developed high temperature, hydrogen permeable membranes that contain no platinum group metals with the goal of separating hydrogen from gas mixtures representative of gasification of carbon feedstocks such as coal or biomass in order to meet DOE NETL 2015 hydrogen membrane performance targets. We employed a dual synthesis strategy centered on transition metal carbides. In the first approach, novel, high temperature, surface diffusion membranes based on nanoporous Mo 2 C were fabricated on ceramic supports. These were produced in a two step process that consisted of molybdenum oxide deposition followed by thermal carburization. Our best Mo 2 C surface diffusion membrane achieved a pure hydrogen flux of 367 SCFH/ft 2 at a feed pressure of only 20 psig. The highest H 2 /N 2 selectivity obtained with this approach was 4.9. A transport model using "dusty gas" theory was derived to describe the hydrogen transport in the Mo 2 C coated, surface diffusion membranes. The second class of membranes developed were dense metal foils of BCC metals such as vanadium coated with thin (< 60 nm) Mo 2 C catalyst layers. We have fabricated a Mo 2 C/V composite membrane that in pure gas testing delivered a H 2 flux of 238 SCFH/ft 2 at 600 °C and 100 psig, with no detectable He permeance. This exceeds the 2010 DOE Target flux. This flux is 2.8 times that of pure Pd at the same membrane thickness and test conditions and over 79% of the 2015 flux target. In mixed gas testing we achieved a permeate purity of ≥99.99%, satisfying the permeate purity milestone, but the hydrogen permeance was low, ~0.2 SCFH/ft 2 .psi. However, during testing of a Mo 2 C coated Pd alloy membrane with DOE 1 feed gas mixture a hydrogen permeance of >2 SCFH/ft 2 .psi was obtained which was stable during the entire test, meeting the permeance associated with the 2010 DOE target flux. Lastly, the Mo 2 C/V composite membranes were shown to be stable for at least 168 hours = one week, including cycling at high temperature and alternating He/H 2 exposure.4

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Section: Permeation Modelmentioning

confidence: 96%

Section: Permeation Modelmentioning

confidence: 99%

Section: Co Tolerance Yes Yesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Nanoporous, Metal Carbide, Surface Diffusion Membranes for High Temperature Hydrogen Separations

Way¹,

Wolden²

2013

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Holey Reduced Graphene Oxide Coupled with an Mo₂N–Mo₂C Heterojunction for Efficient Hydrogen Evolution

et al. 2017

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An in situ catalytic etching strategy is developed to fabricate holey reduced graphene oxide along with simultaneous coupling with a small-sized Mo N-Mo C heterojunction (Mo N-Mo C/HGr). The method includes the first immobilization of H PMo O (PMo ) clusters on graphite oxide (GO), followed by calcination in air and NH to form Mo N-Mo C/HGr. PMo not only acts as the Mo heterojunction source, but also provides the Mo species that can in situ catalyze the decomposition of adjacent reduced GO to form HGr, while the released gas (CO) and introduced NH simultaneously react with the Mo species to form an Mo N-Mo C heterojunction on HGr. The hybrid exhibits superior activity towards the hydrogen evolution reaction with low onset potentials of 11 mV (0.5 m H SO ) and 18 mV (1 m KOH) as well as remarkable stability. The activity in alkaline media is also superior to Pt/C at large current densities (>88 mA cm ). The good activity of Mo N-Mo C/HGr is ascribed to its small size, the heterojunction of Mo N-Mo C, and the good charge/mass-transfer ability of HGr, as supported by a series of experiments and theoretical calculations.

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Renewable Aromatics from Kraft Lignin with Molybdenum‐Based Catalysts

et al. 2017

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The catalytic depolymerization of Kraft lignin in supercritical ethanol was explored in the presence of Mo2C- and MoS2-based catalysts. At 280 °C, Mo2C and Mo2C/Al2O3 afforded aromatic yields of 425 and 419 mg/g lignin, respectively: amongst the highest yields reported to date. Ionic-liquid-assisted delamination of MoS2 resulted in highly active catalysts, capable of quantitative conversion of lignin at the expense of aromatic yield (ca 186 mg/g lignin). Across all the catalysts studied, between 0.04 wt% and 0.38 wt% of molybdenum leached into solution under supercritical conditions, according to ICP analyses (corresponding to 27–570 µg of molybdenum in the reaction supernatant). A small contribution to the molybdenum in solution comes from the reactor itself (Hastelloy C contains 16 wt% Mo). Analysis of a depolymerization performed with fresh Kraft lignin and the soluble portion of the reaction mixture from a previous reactor run indicated that the leached species were neither active enough to afford the high conversions observed, nor selective enough to give high yields of aromatic products. In conjunction with the ICP data and differential chemoselectivities of the Mo2C- and MoS2-based catalysts, these results suggest that the bulk of the catalysis is heterogeneous

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Dense Carbide/Metal Composite Membranes for Hydrogen Separations Without Platinum Group Metals

Cited by 38 publications

References 19 publications

Nanoporous, Metal Carbide, Surface Diffusion Membranes for High Temperature Hydrogen Separations

Nanoporous, Metal Carbide, Surface Diffusion Membranes for High Temperature Hydrogen Separations

Holey Reduced Graphene Oxide Coupled with an Mo₂N–Mo₂C Heterojunction for Efficient Hydrogen Evolution

Renewable Aromatics from Kraft Lignin with Molybdenum‐Based Catalysts

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Dense Carbide/Metal Composite Membranes for Hydrogen Separations Without Platinum Group Metals

Cited by 38 publications

References 19 publications

Nanoporous, Metal Carbide, Surface Diffusion Membranes for High Temperature Hydrogen Separations

Nanoporous, Metal Carbide, Surface Diffusion Membranes for High Temperature Hydrogen Separations

Holey Reduced Graphene Oxide Coupled with an Mo2N–Mo2C Heterojunction for Efficient Hydrogen Evolution

Renewable Aromatics from Kraft Lignin with Molybdenum‐Based Catalysts

Contact Info

Product

Resources

About

Holey Reduced Graphene Oxide Coupled with an Mo₂N–Mo₂C Heterojunction for Efficient Hydrogen Evolution