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Microwave Heating and Chemistry...
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Microwave Heating and Chemistry

A special issue of Processes (ISSN 2227-9717). This special issue belongs to the section "Chemical Processes and Systems".

Deadline for manuscript submissions: closed (15 December 2019) | Viewed by 17332

Special Issue Editors

Dr. Shuntaro Tsubaki

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Guest Editor
School of Materials and Chemical Technology, Tokyo Institute of Technology, Ookayama 2-12-1 E4-3, Meguro, Tokyo 152-8550, Japan
Interests: biomass conversion; green chemistry; hydrothermal chemistry; microwave chemistry
Dr. Tomohiko Mitani

E-Mail Website
Guest Editor
Research Institute of Sustainable Humanosphere, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
Interests: microwave heating; wireless power transfer; microwave engineering
Dr. Jun Fukushima

E-Mail Website
Guest Editor
Graduate School of Engineering, Department of Applied Chemistry, Tohoku University, 6-6-07, Aoba Aramaki, Aoba-ku, Sendai, Miyagi 980-8579, Japan
Interests: microwave processing; ceramics; functional material; nonequilibrium processing; carbon recycling

Special Issue Information

Dear Colleagues,

Under the Paris Agreement, reductions of carbon dioxide emission are strongly required in various industrial processes. Renewable-energy-based electrification of chemical processes is one of the important goals. Unlike the conventional heating method using heat transfer, microwave heating enables material-selective and rapid heating and is expected as a key technology to achieve electrified and energy-efficient industrial processes. For example, microwaves have already been put to practical use in industrial processes such as food processing, rubber vulcanization, drying, and extraction. By making use of its unique heating mode, microwaves can be also applied to broader range of chemical processes including material processing, fine-chemical syntheses (electronic materials and pharmaceuticals) and bulk chemical production in the near future.

This Special Issue on “Microwave Heating and Chemistry” aims to curate novel advances in the development and application of microwave heating to various chemical processes. Topics include, but are not limited to:

  • Aplications of microwaves to organic and inorganic chemical reactions, material processing, plasma procressing, food processing, waste treatments, biomass conversion, etc.
  • Design and engineering of microwave-assisted chemical processes including computational modeling.
  • Development of new microwave devices and applicators for chemical processes (e.g. semiconductor generator, phase-controlled, modulated and pulsed microwaves).
  • Evaluation of process and energy efficiency of microwave-assisted chemical processes.

Dr. Tsubaki Shuntaro
Prof. Tomohiko Mitani
Dr. Jun Fukushima
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Processes is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • microwave-assisted chemical reaction
  • microwave chemistry
  • intelligent microwave heating
  • industrial microwave process

Published Papers (6 papers)

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Research

13 pages, 12149 KiB  
Article
Drastic Microwave Heating of Percolated Pt Metal Nanoparticles Supported on Al2O3 Substrate
by Taishi Ano, Masato M. Maitani, Yuka Sato, Shuntaro Tsubaki and Yuji Wada
Processes 2020, 8(1), 72; https://doi.org/10.3390/pr8010072 - 05 Jan 2020
Cited by 9 | Viewed by 2899
Abstract
Microwave (MW) heating of supported metal nanoparticles (NPs) presents attractive effects on catalysis such as the rapid heating processes and the enhancement of the reaction rate. Improving the heating property of the NPs, which act as the catalytic active sites, the MW effects [...] Read more.
Microwave (MW) heating of supported metal nanoparticles (NPs) presents attractive effects on catalysis such as the rapid heating processes and the enhancement of the reaction rate. Improving the heating property of the NPs, which act as the catalytic active sites, the MW effects will become more significant. Here we show a systematic study about the supported Pt NPs structure to improve the MW heating property. We found that the drastic heating was induced by a percolated Pt NPs structure, where the conduction electrons move around in the two-dimensional network. On the other hand, no heating was observed in an isolated Pt NPs system with the confined electrons. We conclude that the percolation of the Pt NPs giving the network structure is one of the important key factors for the efficient MW heating. The optimized Pt NPs catalyst leads to the dramatic MW effects on catalytic reactions. Full article
(This article belongs to the Special Issue Microwave Heating and Chemistry )
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9 pages, 2432 KiB  
Article
Microwave Heating Behavior in SiC Fiber-MO2 Mixtures (M = Ce, Zr)—Selective Heating of Micrometer-Sized Fibers Facilitated by ZrO2 Powder
by Keiichiro Kashimura, Jun Fukushima, Tomoaki Namioka, Takashi Fujii, Hirotsugu Takizawa and Hideoki Fukushima
Processes 2020, 8(1), 47; https://doi.org/10.3390/pr8010047 - 01 Jan 2020
Cited by 4 | Viewed by 2350
Abstract
SiC fiber-MO2 (M = Ce, Zr) mixtures with various compositions were heated by applying an 80 W microwave electric field, to investigate their heating rate, maximum temperature, and dielectric constant. For the SiC fiber-CeO2 mixture, all three parameters [...] Read more.
SiC fiber-MO2 (M = Ce, Zr) mixtures with various compositions were heated by applying an 80 W microwave electric field, to investigate their heating rate, maximum temperature, and dielectric constant. For the SiC fiber-CeO2 mixture, all three parameters continued to increase as the weight ratio of the SiC fiber increased; in contrast, for the SiC fiber-ZrO2 mixture, these parameters reached a maximum value at a certain composition. A thermal gradient of 500 °C was observed at a microlevel in the SiC fiber-ZrO2 mixture, and hot spots were located in regions with a certain composition. This result not only contributes to designing a novel good microwave absorber but also presents new aspects with regard to high-temperature microwave processing, including the mechanism behind the high-temperature gradients on the order of micrometers as well as engineering applications that utilize these high-temperature gradients. Full article
(This article belongs to the Special Issue Microwave Heating and Chemistry )
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9 pages, 2379 KiB  
Article
Nitridation Reaction of Titanium Powders by 2.45 GHz Multimode Microwave Irradiation using a SiC Susceptor in Atmospheric Conditions
by Jun Fukushima, Keiichiro Kashimura and Hirotsugu Takizawa
Processes 2020, 8(1), 20; https://doi.org/10.3390/pr8010020 - 21 Dec 2019
Cited by 4 | Viewed by 2817
Abstract
A titanium nitride (TiN) coating using microwaves can be accomplished in air, and satisfies the required conditions of an on-demand TiN coating process. However, the coating mechanism using microwaves is not completely clear. In this study, to understand the detailed mechanism of microwave [...] Read more.
A titanium nitride (TiN) coating using microwaves can be accomplished in air, and satisfies the required conditions of an on-demand TiN coating process. However, the coating mechanism using microwaves is not completely clear. In this study, to understand the detailed mechanism of microwave titanium nitridation in air, the quantity of nitrogen and oxygen in reacted TiN powder has been investigated by an inert melting method. Titanium powders were irradiated with microwaves by a multi-mode type 2.45 GHz microwave irradiation apparatus, while also being held at various temperatures for two different dwell times. X-ray diffraction (XRD) results revealed that nitridation of the powder progressed with increasing process temperature, and the nitridation corresponds to the powder color after microwave irradiation. The nitrogen contents of the samples increased with increasing processing temperature and dwell time, unlike oxygen. It is postulated that the reaction of convected air with titanium is a key role to control nitridation in this system. Full article
(This article belongs to the Special Issue Microwave Heating and Chemistry )
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12 pages, 3031 KiB  
Article
Joining of Al2O3 Rods Using Microwaves and Employing Sic Particles as Adhesive
by Natsuko Kimura, Takashi Fujii, Keiichiro Kashimura and Wataru Nakao
Processes 2019, 7(10), 750; https://doi.org/10.3390/pr7100750 - 15 Oct 2019
Cited by 1 | Viewed by 2312
Abstract
The joining of Al2O3 rods using SiC particles in a microwave field was examined. SiC with high microwave absorption characteristics is coated on the fracture surface of Al2O3 rods. Then, microwave irradiation is performed using a 2.45 [...] Read more.
The joining of Al2O3 rods using SiC particles in a microwave field was examined. SiC with high microwave absorption characteristics is coated on the fracture surface of Al2O3 rods. Then, microwave irradiation is performed using a 2.45 GHz single-mode cavity and the Al2O3 rods are rapidly joined. Energy dispersive X-ray spectroscopy reveals that the substance generated on the joining surface comprises Al and O. It is believed that the SiC interacts with the microwave to generate microwave plasma and that the plasma melts the Al2O3 rods. Thus, the matrix melts and the fracture surfaces are joined. Full article
(This article belongs to the Special Issue Microwave Heating and Chemistry )
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16 pages, 3922 KiB  
Article
Sweep Frequency Heating based on Injection Locked Magnetron
by Fengming Yang, Wenwen Wang, Bo Yan, Tao Hong, Yang Yang, Huacheng Zhu, Li Wu and Kama Huang
Processes 2019, 7(6), 341; https://doi.org/10.3390/pr7060341 - 05 Jun 2019
Cited by 13 | Viewed by 3000
Abstract
Conventional microwave heating has serious problems such as non-uniform heating and low efficiency. A novel magnetron microwave sweep frequency heating method is proposed to improve microwave heating uniformity. In this method, the frequency-sweeping signal is injected into the magnetron by the injection frequency-locking [...] Read more.
Conventional microwave heating has serious problems such as non-uniform heating and low efficiency. A novel magnetron microwave sweep frequency heating method is proposed to improve microwave heating uniformity. In this method, the frequency-sweeping signal is injected into the magnetron by the injection frequency-locking technique, and the microwave sweep frequency heating of the magnetron is realized. In this paper, a complicated injection frequency locking system is given and analyzed and a multiphysics calculation model based on the finite element method for electromagnetic waves and heat transfer is established. The calculation of microwave sweep frequency heating is realized by the combination of COMSOL and MATLAB. The results show that the sweep frequency heating has an obvious superiority. An experiment is carried out to verify the simulation results. The simulation results are in agreement with the experimental data. Moreover, the effect of sweep bandwidth and sweep interval on heating uniformity is discussed. Full article
(This article belongs to the Special Issue Microwave Heating and Chemistry )
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13 pages, 3303 KiB  
Article
High-Temperature Permittivity and Microwave Pretreatment Characteristics of Nickel-Containing Sludge from Battery Production
by Zhanyong Guo, Ping Guo, Guang Su, Demei Zhai, Fang Cheng and Fachuang Li
Processes 2019, 7(5), 257; https://doi.org/10.3390/pr7050257 - 03 May 2019
Cited by 5 | Viewed by 3173
Abstract
Permittivity is a vitally important parameter for the description of the absorption and heating characteristics of materials under microwave irradiation. In this paper, the permittivity of nickel-containing sludge (NCS), which is created during battery production as a cheap secondary resource, was measured at [...] Read more.
Permittivity is a vitally important parameter for the description of the absorption and heating characteristics of materials under microwave irradiation. In this paper, the permittivity of nickel-containing sludge (NCS), which is created during battery production as a cheap secondary resource, was measured at temperatures from 20 °C to 600 °C at 2.45 GHz using the cavity perturbation method. In addition, the loss tangent (tanδ) and penetration depth (Dp) of microwaves into the material were calculated. The results of the permittivity study show that the dielectric constant (ε′) and dielectric loss factor (ε″) of the NCS increase with increasing temperature. The variations of the loss tangent (tanδ) and penetration depth (Dp) with the temperature can be divided into two parts at 200 °C. The effect of the initial moisture content on the dielectric properties of the material is notably greater than that of the temperature, which was confirmed by the heating curve. After microwave pretreatment, the nickel-containing phase is transformed into NiO, while the weight of NCS is reduced by more than 20%, the particle size is significantly reduced and the leaching time reduce 20 min than that of conventional heating. Full article
(This article belongs to the Special Issue Microwave Heating and Chemistry )
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