Catalytic molten metals for the direct conversion of methane to hydrogen and separable carbon

Upham, D. Chester; Agarwal, Vishal; Khechfe, Alexander A.; Snodgrass, Zachary R.; Gordon, Michael J.; Metiu, Horia; McFarland, Eric W.

doi:10.1126/science.aao5023

Cited by 360 publications

(339 citation statements)

References 40 publications

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“…So the reader is referred to the next section for a detailed description. In line with previous reports, we find that Pt holds a negative charge in the alloy, making the platinum atoms being in repulsive coulomb interaction one with respect to the other, which likely explains why they do not aggregate in the alloy …”

Section: Resultssupporting

confidence: 93%

“…From an electronic point of view (Figure ), the clusters are negatively or very slightly positively charged over the whole composition range, which indicates that the support gives electrons to the cluster through the γ‐Al 2 O 3 (100) facet, as this was already the case for pure platinum . Pt atoms are negatively charged, tin atoms are positively charged, which indicates a charge transfer from Sn atoms to Pt atoms, consistently with the respective electronegativity values of the atomic species (1.8 for Sn and 2.2 for Pt in the Pauling scale), with previous computational studies for clusters and surfaces, and with XANES experiments . Our results also shows that tin tends to be partially oxidized in the nano‐alloy.…”

Section: Resultssupporting

confidence: 82%

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Atomistic Models for Highly‐Dispersed PtSn/γ‐Al₂O₃ Catalysts: Ductility and Dilution Affect the Affinity for Hydrogen

et al. 2019

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Supported platinum‐based sub‐nanometric particles play a central role in many catalytic applications. In particular, platinum‐tin active phases supported on γ‐Al2O3 are largely employed for dehydrogenation of alkanes and catalytic reforming of naphtha cuts, although geometric and electronic effects of the active phase in the presence of hydrogen still remains highly debated. Thanks to periodic density functional theory (DFT), we propose structural models of such systems containing thirteen metal atoms (PtxSn13‐x with 0≤x≤13) deposited on the (100) γ‐Al2O3 surface. We thus unravel the intricate effects of the composition (Pt/Sn ratio), of the support (γ‐Al2O3) and the hydrogen coverage on the stability of platinum‐tin sub‐nanometric clusters, in the case where tin is reduced (Sn0). A detailed investigation of the interaction of the supported Pt10Sn3 cluster with hydrogen by velocity‐scaled molecular dynamics provides a mapping of the hydrogen coverage as a function of the operating conditions (T, P(H2)). Our study highlights significant differences between Pt13 and PtxSn13‐x clusters in terms of ductility and dilution (also called ensemble) effects which may be at the origin of the different reactivities usually reported for Pt and PtSn supported catalysts.

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Section: Resultssupporting

confidence: 93%

Section: Resultssupporting

confidence: 82%

Atomistic Models for Highly‐Dispersed PtSn/γ‐Al₂O₃ Catalysts: Ductility and Dilution Affect the Affinity for Hydrogen

et al. 2019

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“…It is well established that molten catalysts are more active than solid metal catalysts [33,43,44,45,46,47,48,49,50,51,52,53,34,35,54,55] but this premise itself does not make them superior. In most cases, a molten metal would increase the cost of the overall process especially when transition metals are used.…”

Section: Validation Of Reaction Pathway Using Density Functional Theorymentioning

confidence: 99%

Enhancement of the Yield of Ammonia by Hydrogen‐Sink Effect during Plasma Catalysis

et al. 2019

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Plasma‐catalytic ammonia synthesis has been known since the early 1900s, but only until now efforts to optimize catalysts for this purpose are emerging. Here, we investigate various transition metals, low‐melting‐point metals, and gallium‐rich alloy catalysts for their activity towards ammonia production under a plasma environment. The best three pure metal catalysts were Ni, Sn and Au, which are not traditional catalysts for the current industrial ammonia synthesis. The ammonia yields for these catalysts were 34 %, 29 %, and 19 %, respectively. Synergistic effects were detected when employing alloys, as some alloys presented ∼25–50 % higher yields than their constituent metals. The employed metals were classified into two categories. Category I metals (Cu, Ag, Au and Fe), which are nitrophobic (excluding Fe, the Haber‐Bosch catalyst) and poor hydrogen sinks. For these metals, the measured concentration of Hα in the gas phase tended to correlate inversely with ammonia yield and directly with the H binding strength on the catalyst surface. Category II metals (Ga, In, Sn and Ni), which are good hydrogen sinks, tend to have a lower concentration of Hα in the gas phase than that of category I metals, which is consistent with their expected sink behavior. For these metals, the concentration of Hα correlates with ammonia yield. Plasma characterization experiments and DFT calculations suggest that the higher performance of Ni and Sn is related to the benefit of dissolving hydrogen to slow down H recombination, which is a feature that could be potentially optimized in future studies by rationally altering the catalyst composition.

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“…Controlling the motion and distribution of gas bubbles in aqueous media is of great significance in gas‐involved physical and chemical processes such as aeration, [ 1 ] hydrogen production, [ 2 ] biological respiration, [ 3 ] etc. Bubble manipulation using an open surface promotes its superiority in mass/energy exchange as it benefits a direct and sufficient interaction between gas and the aqueous solution.…”

Section: Figurementioning

confidence: 99%

A Multi‐Bioinspired Dual‐Gradient Electrode for Microbubble Manipulation toward Controllable Water Splitting

et al. 2020

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between gas and the aqueous solution. [4] Thus, a number of research groups were devoted to designing specific surfaces with specific controllability of bubbles, e.g., superhydrophobic cone, [5] superaerophilic geometry-gradient channel, [6] lubricantinfused slippery surface, [7] elastic liquidinfused material, [8] Janus mesh, [9] etc. Previous studies, to some extent, have realized spontaneous and directional bubble transport underwater, including 1D bubble transport along channels with the assistance of wettability gradient derived from a Janus interconnected structure, [9,10] 2D transport depending on specific inclined planes with the aid of buoyancy or on specific asymmetric surfaces with geometric gradient, [11] demonstrating meaningful but limited bubble transport processes. Further integration of different controlling strategies can diversify the bubble controlling strategy, which should unlock more options for applying such interfaces in extensive fields. [12] For instance, Yong and co-workers demonstrated an effective self-driven gas separation system based on a monolithic photovoltaic-electrolysis device, of which the key idea is gas bubble manipulation by a slippery porous surface and buoyant force. [12b] Zhang et al. incorporated an asymmetric star-shaped slippery track with copper wire cathode, which realized continuous electrolysis and efficient collection of H 2 microbubbles in a pressured environment. [12c] The regulation of bubble transport in aqueous environments is more attractive to broaden the applications of underwater bubble manipulation yet much more challenging because of the increased complexity in dominating bubble transport direction.Water splitting is a promising strategy to produce hydrogen and oxygen synergistically, which is a typical gas-related underwater chemical reaction. [13] The regulation of bubble generation and collection should offer a great opportunity to develop advanced and integrated water-splitting devices toward practical energy production, whereas urgently to be addressed is how to acquire pure product gases. [14] Classical resolutions are introducing ion exchange membranes that prevent the potential gases mixing, but this membrane-based system has demerits in high cost and low durability of membrane modules. [15] Membrane-less electrolysis that gets rid of the membranes from the system and replaces with fluid manipulation to separate the product gases has recently emerged and exhibits superiority Clean energy generated from total water splitting is expected to be an affordable, sustainable, and reliable resource but it remains a challenge to gain pure fuel with a controllable pathway. Here, a simple and economical strategy that enables in situ separation of H 2 /O 2 product by manipulating the generated gas phases with the aid of multi-bioinspired electrodes is proposed. This versatile electrode is based on a Janus asymmetric foam with dual gradients, i.e., the wettability gradient promotes the one-way gas penetration and the geometry gradient boosts the sp...

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Catalytic molten metals for the direct conversion of methane to hydrogen and separable carbon

Cited by 360 publications

References 40 publications

Atomistic Models for Highly‐Dispersed PtSn/γ‐Al₂O₃ Catalysts: Ductility and Dilution Affect the Affinity for Hydrogen

Atomistic Models for Highly‐Dispersed PtSn/γ‐Al₂O₃ Catalysts: Ductility and Dilution Affect the Affinity for Hydrogen

Enhancement of the Yield of Ammonia by Hydrogen‐Sink Effect during Plasma Catalysis

A Multi‐Bioinspired Dual‐Gradient Electrode for Microbubble Manipulation toward Controllable Water Splitting

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Catalytic molten metals for the direct conversion of methane to hydrogen and separable carbon

Cited by 360 publications

References 40 publications

Atomistic Models for Highly‐Dispersed PtSn/γ‐Al2O3 Catalysts: Ductility and Dilution Affect the Affinity for Hydrogen

Atomistic Models for Highly‐Dispersed PtSn/γ‐Al2O3 Catalysts: Ductility and Dilution Affect the Affinity for Hydrogen

Enhancement of the Yield of Ammonia by Hydrogen‐Sink Effect during Plasma Catalysis

A Multi‐Bioinspired Dual‐Gradient Electrode for Microbubble Manipulation toward Controllable Water Splitting

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Product

Resources

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Atomistic Models for Highly‐Dispersed PtSn/γ‐Al₂O₃ Catalysts: Ductility and Dilution Affect the Affinity for Hydrogen

Atomistic Models for Highly‐Dispersed PtSn/γ‐Al₂O₃ Catalysts: Ductility and Dilution Affect the Affinity for Hydrogen