Research

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16 pages, 3869 KiB

Open AccessArticle

Sponge-like CoNi Catalysts Synthesized by Combustion of Reactive Solutions: Stability and Performance for CO₂ Hydrogenation

by Nikolay Evdokimenko, Zhanna Yermekova, Sergey Roslyakov, Olga Tkachenko, Gennady Kapustin, Denis Bindiug, Alexander Kustov and Alexander S. Mukasyan

Materials 2022, 15(15), 5129; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15155129 - 23 Jul 2022

Cited by 7 | Viewed by 2303

Abstract

Active and stable catalysts are essential for effective hydrogenation of gaseous CO₂ into valuable chemicals. This work focuses on the structural and catalytic features of single metals, i.e., Co and Ni, as well as bimetallic CoNi alloy catalysts synthesized via combustion of [...] Read more.

Active and stable catalysts are essential for effective hydrogenation of gaseous CO₂ into valuable chemicals. This work focuses on the structural and catalytic features of single metals, i.e., Co and Ni, as well as bimetallic CoNi alloy catalysts synthesized via combustion of reactive sol-gels. Different characterization methods were used for studying the relationships between the structure, composition, and catalytic activity of the fabricated materials. All catalysts exhibited highly porous sponge-like microstructure. The outermost surfaces of the CoNi alloys were more saturated with Co, while a stoichiometric Co/Ni ratio was observed for the particle’s bulk. Catalytic properties of the as-synthesized powders were studied in the CO₂ hydrogenation reaction at 300 °C for over 80 h of time on stream. All the catalysts demonstrated exceptional selectivity with respect to CH₄ formation. However, the combination of elemental Co and Ni in a single phase resulted in a synergistic effect in bulk alloy catalysts, with activity twofold to threefold that of single-metal catalysts. The activity and stability of the CoNi₃ catalyst were higher than those previously reported for Ni-based catalysts. The reasons for this behavior are discussed. Full article

(This article belongs to the Special Issue Structure and Properties of Nanoparticles in Flame/Combustion)

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7 pages, 3490 KiB

Open AccessArticle

Nanoparticle Generation in Glowing Wire Generator: Insight into Nucleation Peculiarities

by Elena Fomenko, Igor Altman, Lucija Boskovic and Igor E. Agranovski

Materials 2021, 14(24), 7775; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14247775 - 16 Dec 2021

Cited by 2 | Viewed by 1717

Abstract

The paper studies nanoparticle formation in a glowing wire generator (GWG), in which the gas carrier flows around heated metal wire, producing aerosols from a vapor released from the surface. The device has been customized, enabling the use of a double-wire in different [...] Read more.

The paper studies nanoparticle formation in a glowing wire generator (GWG), in which the gas carrier flows around heated metal wire, producing aerosols from a vapor released from the surface. The device has been customized, enabling the use of a double-wire in different orientations in regard to the gas flow. Such alterations provided different effective distances between wires enabling investigation of their mutual influence. Concentration of particles produced in the GWG at different parameters (applied voltage and a gas flow) was carefully measured and analysed. Different regimes of a nanoparticle nucleation were identified that resulted from the applied voltage variation and the gas flow direction. In particular, independent nucleation of nanoparticles on both parts of the wire occurred in the wire plane’s configuration perpendicular to the gas flow, whilst dependent nucleation of nanoparticles was observed at a certain specific set of parameters in the configuration, in which the wire plane was parallel to the gas flow. Two corresponding functions were introduced in order to quantify those nucleation regimes and they tend to zero when either independent or dependent nucleation occur. The peculiarities found ought to be considered when designing the multi-wire GWGs in order to further extend the device’s range for industrial applications. Full article

(This article belongs to the Special Issue Structure and Properties of Nanoparticles in Flame/Combustion)

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Review

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35 pages, 5194 KiB

Open AccessReview

Flame Synthesis of Carbon and Metal-Oxide Nanoparticles: Flame Types, Effects of Combustion Parameters on Properties and Measurement Methods

by Raul Serrano-Bayona, Carson Chu, Peng Liu and William L. Roberts

Materials 2023, 16(3), 1192; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16031192 - 30 Jan 2023

Cited by 7 | Viewed by 2351

Abstract

Carbon and metal-oxide nanoparticles (NP) are currently synthesized worldwide for various applications in the solar-energy, optical, pharmaceutical, and biomedical industries, among many others. Gas phase methods comprise flame synthesis and flame spray pyrolysis (FSP), which provide high efficiency, low cost, and the possibility [...] Read more.

Carbon and metal-oxide nanoparticles (NP) are currently synthesized worldwide for various applications in the solar-energy, optical, pharmaceutical, and biomedical industries, among many others. Gas phase methods comprise flame synthesis and flame spray pyrolysis (FSP), which provide high efficiency, low cost, and the possibility of large-scale applications. The variation of combustion operation parameters exerts significant effects on the properties of the NPs. An analysis of the latest research results relevant to NP flame synthesis can provide new insight into the optimization of these methods and the development of these techniques for a large scale. This review offers insight into the current status of flame synthesis for carbon and metal-oxide NPs—specifically containing analysis and comparison of the most common carbon and metal-oxide NP production techniques. The burner configurations used at the laboratory scale and large scale are also discussed, followed by the assessment of the influence of combustion parameters on the properties of NPs. Finally, the features of the measurement techniques applied for determining NP properties were described. Full article

(This article belongs to the Special Issue Structure and Properties of Nanoparticles in Flame/Combustion)

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