Reactions

Editorial

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2 pages, 178 KiB

Open AccessEditorial

Editorial for Special Issue “Hydrogen Production and Storage”

by Valérie Meille, Luis M. Gandía, Sibudjing Kawi and Francesco Frusteri

Reactions 2022, 3(1), 87-88; https://doi.org/10.3390/reactions3010007 - 17 Jan 2022

Viewed by 2095

Abstract

Hydrogen appears as an unavoidable energy vector and an almost miracle solution to global warming for many people [...] Full article

(This article belongs to the Special Issue Hydrogen Production and Storage)

Research

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14 pages, 2404 KiB

Open AccessArticle

Microstructure and Hydrogen Storage Properties of the Multiphase Ti_0.3V_0.3Mn_0.2Fe_0.1Ni_0.1 Alloy

by Salma Sleiman, Maria Moussa and Jacques Huot

Reactions 2021, 2(3), 287-300; https://doi.org/10.3390/reactions2030018 - 23 Aug 2021

Cited by 9 | Viewed by 2864

Abstract

The hydrogen storage properties of a multi-component alloy of composition Ti_0.3V_0.3Mn_0.2Fe_0.1Ni_0.1 were investigated. The alloy was synthesized by arc melting and mechanical alloying, resulting in different microstructures. It was found that the as-cast alloy [...] Read more.

The hydrogen storage properties of a multi-component alloy of composition Ti_0.3V_0.3Mn_0.2Fe_0.1Ni_0.1 were investigated. The alloy was synthesized by arc melting and mechanical alloying, resulting in different microstructures. It was found that the as-cast alloy is multiphase, with a main C14 Laves phase matrix along with a BCC phase and a small amount of Ti₂Fe-type phase. The maximum hydrogen storage capacity of the alloy was 1.6 wt.%. We found that the air-exposed samples had the same capacity as the as-cast sample but with a longer incubation time. Synthesis by mechanical alloying for five hours resulted in an alloy with only BCC structure. The hydrogen capacity of the milled alloy was 1.2 wt.%, lower than the as-cast one. The effect of ball milling of the as-cast alloy was also studied. Ball milling for five hours produced a BCC structure similar to the one obtained by milling the raw materials for the same time. Full article

(This article belongs to the Special Issue Hydrogen Production and Storage)

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18 pages, 2416 KiB

Open AccessArticle

Adsorption-Based Hydrogen Storage in Activated Carbons and Model Carbon Structures

by Anatoly Fomkin, Anatoly Pribylov, Ilya Men’shchikov, Andrey Shkolin, Oleg Aksyutin, Alexander Ishkov, Konstantin Romanov and Elena Khozina

Reactions 2021, 2(3), 209-226; https://doi.org/10.3390/reactions2030014 - 7 Jul 2021

Cited by 24 | Viewed by 6543

Abstract

The experimental data on hydrogen adsorption on five nanoporous activated carbons (ACs) of various origins measured over the temperature range of 303–363 K and pressures up to 20 MPa were compared with the predictions of hydrogen density in the slit-like pores of model [...] Read more.

The experimental data on hydrogen adsorption on five nanoporous activated carbons (ACs) of various origins measured over the temperature range of 303–363 K and pressures up to 20 MPa were compared with the predictions of hydrogen density in the slit-like pores of model carbon structures calculated by the Dubinin theory of volume filling of micropores. The highest amount of adsorbed hydrogen was found for the AC sample (ACS) prepared from a polymer mixture by KOH thermochemical activation, characterized by a biporous structure: 11.0 mmol/g at 16 MPa and 303 K. The greatest volumetric capacity over the entire range of temperature and pressure was demonstrated by the densest carbon adsorbent prepared from silicon carbide. The calculations of hydrogen density in the slit-like model pores revealed that the optimal hydrogen storage depended on the pore size, temperature, and pressure. The hydrogen adsorption capacity of the model structures exceeded the US Department of Energy (DOE) target value of 6.5 wt.% starting from 200 K and 20 MPa, whereas the most efficient carbon adsorbent ACS could achieve 7.5 wt.% only at extremely low temperatures. The initial differential molar isosteric heats of hydrogen adsorption in the studied activated carbons were in the range of 2.8–14 kJ/mol and varied during adsorption in a manner specific for each adsorbent. Full article

(This article belongs to the Special Issue Hydrogen Production and Storage)

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14 pages, 2752 KiB

Open AccessArticle

Evaluation of Impurity Concentration Process and Mitigation Operation in Fuel Cell System for Using Biogas

by Yutaro Akimoto, Yuta Minei and Keiichi Okajima

Reactions 2021, 2(2), 115-128; https://doi.org/10.3390/reactions2020010 - 25 May 2021

Cited by 5 | Viewed by 3231

Abstract

For a low-carbon society, it is necessary to extract hydrogen for fuel cells from biogas rather than from fossil fuels. However, impurities contained in the biogas affect the fuel cell; hence, there is a need for system and operation methods to remove these [...] Read more.

For a low-carbon society, it is necessary to extract hydrogen for fuel cells from biogas rather than from fossil fuels. However, impurities contained in the biogas affect the fuel cell; hence, there is a need for system and operation methods to remove these impurities. In this study, to develop a fuel cell system for the effective utilization of biogas-derived hydrogen, the compositional change and concentration of impurities in the hydrogen recirculation system under actual operation were evaluated using process simulation. Then, the mitigation operation for performance degradation using simple purification methods was evaluated on the proton exchange membrane fuel cells (PEMFC) stack. In the process simulation of the hydrogen recirculation system, including the PEMFC stack, the concentration of impurities remained at a level that did not pose a problem to the performance. In the constant voltage test for a simulated gas supply of biogas-derived hydrogen, the conditions for applying the methanation reforming and air bleeding methods were analyzed. As a result, methanation reforming is more suitable for supplying biogas-containing CO to the PEMFC stack for continuous operation. Full article

(This article belongs to the Special Issue Hydrogen Production and Storage)

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16 pages, 3249 KiB

Open AccessArticle

Design and Test of a Miniature Hydrogen Production Integrated Reactor

by Ion Velasco, Oihane Sanz, Iñigo Pérez-Miqueo, Iñigo Legorburu and Mario Montes

Reactions 2021, 2(2), 78-93; https://doi.org/10.3390/reactions2020007 - 16 Apr 2021

Cited by 2 | Viewed by 2613

Abstract

A detailed study of the experimental issues involved in the design and operation of a methanol steam microreformer is presented in this paper. Micromachining technology was utilized to fabricate a metallic microchannel block coupling the exothermic and endothermic process. The microchannel block was [...] Read more.

A detailed study of the experimental issues involved in the design and operation of a methanol steam microreformer is presented in this paper. Micromachining technology was utilized to fabricate a metallic microchannel block coupling the exothermic and endothermic process. The microchannel block was coated with a Pd/ZnO catalyst in the reforming channels and with Pd/Al₂O₃ in the combustion channels by washcoating. An experimental system had been designed and fine-tuned allowing estimation of the heat losses of the system and to compensate for them by means of electric heating cartridges. In this way, the heat necessary for the reforming reaction is provided by methanol combustion, thanks to the temperature and flow cascade controller we developed. Thus, the coupling of both reactions in a block of microchannels without the interference caused by significant heat loss due to the small size of the laboratory microreactor could be studied. Runs of this microreformer device were carried out, varying the deposited catalyst amount, methanol steam reforming temperature and space velocity. When the reforming reaction was compensated by the combustion reaction and the heat losses by the electric heating, an almost isothermal behavior of the microchannel reactor was observed. In the less favorable case, with a 460 mg catalyst load, ΔT_MSR was about 8 K and ΔT_COMB was about 16 K. This confirmed good coupling of the methanol steam reforming and the methanol combustion. Full article

(This article belongs to the Special Issue Hydrogen Production and Storage)

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13 pages, 10602 KiB

Open AccessArticle

Low-Temperature Methane Partial Oxidation over Pd Supported on CeO₂: Effect of the Preparation Method and Precursors

by Shiva Fazlikeshteli, Xavier Vendrell and Jordi Llorca

Reactions 2021, 2(1), 30-42; https://doi.org/10.3390/reactions2010004 - 17 Feb 2021

Cited by 11 | Viewed by 4102

Abstract

The catalytic production of syngas by the partial oxidation of methane (POM) was investigated over Pd supported on ceria (0.5–2 Pd wt.%) prepared by incipient wetness impregnation and by mechanochemical methods. The performance of the Pd/CeO₂ catalyst prepared by milling CeO₂ [...] Read more.

The catalytic production of syngas by the partial oxidation of methane (POM) was investigated over Pd supported on ceria (0.5–2 Pd wt.%) prepared by incipient wetness impregnation and by mechanochemical methods. The performance of the Pd/CeO₂ catalyst prepared by milling CeO₂ and Pd acetate was superior to that prepared by milling CeO₂ and Pd nitrate and to Pd/CeO₂ prepared by impregnation from Pd acetate. The best catalytic activity of the Pd/CeO₂ catalyst prepared from CeO₂ and Pd acetate was obtained by milling at 50 Hz for 5 min. Two-step combustion and reforming reaction mechanism were identified. Remarkably, methane conversion increased progressively with Pd loading for the catalysts prepared by incipient wetness impregnation, whereas low metal loading showed better conversion of methane for the catalysts prepared by ball milling using Pd acetate. This was explained in terms of an impressive dispersion of Pd species with a strong interaction with the surface of ceria, as deduced from transmission electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy characterization, which revealed a large quantity of highly oxidized species at the surface. Full article

(This article belongs to the Special Issue Hydrogen Production and Storage)

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9 pages, 2439 KiB

Open AccessArticle

Influence of Nanoconfinement on the Hydrogen Release Processes from Sodium Alanate

by Kenneth Tuul and Rasmus Palm

Reactions 2021, 2(1), 1-9; https://doi.org/10.3390/reactions2010001 - 18 Jan 2021

Cited by 8 | Viewed by 2726

Abstract

Sodium alanate (NaAlH₄) is a prospective H₂ storage material for stationary and mobile applications, as NaAlH₄ contains 7.4 wt% of H₂, and it is possible to do multiple H₂ release and accumulation cycles. Nanoconfinement is a [...] Read more.

Sodium alanate (NaAlH₄) is a prospective H₂ storage material for stationary and mobile applications, as NaAlH₄ contains 7.4 wt% of H₂, and it is possible to do multiple H₂ release and accumulation cycles. Nanoconfinement is a potential solution to enhance the H₂ release properties of NaAlH₄. To optimize the supporting material and the synthesis method used for the nanoconfinement of NaAlH₄, a better understanding of the influence of nanoconfinement on the H₂ release processes is necessary. Thus, the H₂ release from bulk, purely nanoconfined, and intermediate NaAlH₄ is measured at different temperature ramp rates, and the characteristic parameters for each hydrogen release process are determined. Activation energies for each process are determined using the Kissinger method, and the effect of nanoconfinement on the activation energies is analysed. The impact of nanoconfinement on the H₂ release processes from NaAlH₄ and the limitations of each process in case of bulk and nanoconfined NaAlH₄ are presented and discussed. Nanoconfinement of NaAlH₄ decreases activation energies of the initial reversible H₂ release steps to between 30 and 45 kJ mol⁻¹ and increased the activation energy of the last irreversible H₂ release step to over 210 kJ mol⁻¹. Full article

(This article belongs to the Special Issue Hydrogen Production and Storage)

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Review

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33 pages, 4727 KiB

Open AccessReview

Smart Designs of Anti-Coking and Anti-Sintering Ni-Based Catalysts for Dry Reforming of Methane: A Recent Review

by Xingyuan Gao, Jangam Ashok and Sibudjing Kawi

Reactions 2020, 1(2), 162-194; https://doi.org/10.3390/reactions1020013 - 14 Dec 2020

Cited by 44 | Viewed by 5626

Abstract

Dry reforming of methane (DRM) reaction has drawn much interest due to the reduction of greenhouse gases and production of syngas. Coking and sintering have hindered the large-scale operations of Ni-based catalysts in DRM reactions at high temperatures. Smart designs of Ni-based catalysts [...] Read more.

Dry reforming of methane (DRM) reaction has drawn much interest due to the reduction of greenhouse gases and production of syngas. Coking and sintering have hindered the large-scale operations of Ni-based catalysts in DRM reactions at high temperatures. Smart designs of Ni-based catalysts are comprehensively summarized in fourth aspects: surface regulation, oxygen defects, interfacial engineering, and structural optimization. In each part, details of the designs and anti-deactivation mechanisms are elucidated, followed by a summary of the main points and the recommended strategies to improve the catalytic performance, energy efficiency, and utilization rate. Full article

(This article belongs to the Special Issue Hydrogen Production and Storage)

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Other

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8 pages, 326 KiB

Open AccessViewpoint

Liquid Organic Hydrogen Carriers or Organic Liquid Hydrides: 40 Years of History

by Valérie Meille and Isabelle Pitault

Reactions 2021, 2(2), 94-101; https://doi.org/10.3390/reactions2020008 - 5 May 2021

Cited by 20 | Viewed by 4896

Abstract

The term LOHC stands for Liquid Organic Hydrogen Carriers. The term has been so well accepted by the scientific community that the studies published before the existence of this name are not very visible. In this mini-review, we have tried to rehabilitate various [...] Read more.

The term LOHC stands for Liquid Organic Hydrogen Carriers. The term has been so well accepted by the scientific community that the studies published before the existence of this name are not very visible. In this mini-review, we have tried to rehabilitate various studies that deserve to be put back in the spotlight in the present context. Studies indeed began in the early 1980s and many publications have compared the use of various organic carriers, various catalysts and reactors. Recent reviews also include the economic aspects of this concept. Full article

(This article belongs to the Special Issue Hydrogen Production and Storage)

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