Enhancement of Fixed-bed Flow Reactions under Microwave Irradiation by Local Heating at the Vicinal Contact Points of Catalyst Particles

Haneishi, Naoto; Tsubaki, Shuntaro; Abe, Eriko; Maitani, Masato M.; Suzuki, Ei ichi; Fujii, Satoshi; Fukushima, Jun; Takizawa, Hirotsugu; Wada, Yuji

doi:10.1038/s41598-018-35988-y

Cited by 82 publications

(51 citation statements)

References 36 publications

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“…Regarding the non-thermal effects, the calculations proved that properties such as the polarizability of transition states and the stabilization of radicals and triplet state influence the reactivity by means of non-thermal effects. In the case of fixed bed flow reactors, an interesting study was carried out by Haneishi et al [28], whose studies allowed to conclude that the generation of local heating at the contact points between the catalyst particles is a key factor for enhancing fixed-bed flow reactions under microwave irradiation. The authors, in the case of the dehydrogenation of 2-propanol over a magnetite catalyst, reported the generation of local high temperature regions between catalyst particles under microwave heating.…”

Section: Microwave Heating Applications In Heterogeneous Catalysismentioning

confidence: 99%

Microwaves and Heterogeneous Catalysis: A Review on Selected Catalytic Processes

et al. 2020

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Since the late 1980s, the scientific community has been attracted to microwave energy as an alternative method of heating, due to the advantages that this technology offers over conventional heating technologies. In fact, differently from these, the microwave heating mechanism is a volumetric process in which heat is generated within the material itself, and, consequently, it can be very rapid and selective. In this way, the microwave-susceptible material can absorb the energy embodied in the microwaves. Application of the microwave heating technique to a chemical process can lead to both a reduction in processing time as well as an increase in the production rate, which is obtained by enhancing the chemical reactions and results in energy saving. The synthesis and sintering of materials by means of microwave radiation has been used for more than 20 years, while, future challenges will be, among others, the development of processes that achieve lower greenhouse gas (e.g., CO 2 ) emissions and discover novel energy-saving catalyzed reactions. A natural choice in such efforts would be the combination of catalysis and microwave radiation. The main aim of this review is to give an overview of microwave applications in the heterogeneous catalysis, including the preparation of catalysts, as well as explore some selected microwave assisted catalytic reactions. The review is divided into three principal topics: (i) introduction to microwave chemistry and microwave materials processing; (ii) description of the loss mechanisms and microwave-specific effects in heterogeneous catalysis; and (iii) applications of microwaves in some selected chemical processes, including the preparation of heterogeneous catalysts.A chemical process is conventionally energized by means of conductive heating with a steam boiler as a typical heat source. Nevertheless, a large variety of other forms of energy can be applied for PI, including ultrasounds (for reactions or crystal nucleation), light (in photocatalytic processes), electric fields (in extraction or for orientation of molecules), or microwaves. The microwave (dielectric) heating of materials has been known for a long time, and microwave ovens have been developed from more than 60 years. The studies by Gedye et al. in 1986 and 1988 [3,4] opened a period of very intensive investigation of the microwave effects on chemical reactions in homogeneous systems. Since then, hundreds of research papers have been published, and research has also expanded toward heterogeneous catalysis and its related chemical processes. This review gives an overview of the application of microwave technology to heterogeneous catalysis, including various chemical processes, as well as to the preparation of catalysts.

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Section: Microwave Heating Applications In Heterogeneous Catalysismentioning

confidence: 99%

Microwaves and Heterogeneous Catalysis: A Review on Selected Catalytic Processes

et al. 2020

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“…Significant efforts have been made to demonstrate the impact of microwave irradiation on thermal and catalytic chemical reactions in contrast to conventional processes. The key conclusions of these efforts include the noticeable improvements of microwaves on conversion, product yield and quality, energy consumption, and reaction rate among other aspects . However, the impact of this energy conversion mechanism on reaction kinetics, in particular activation energies and molecular mobility, is still undocumented.…”

Section: Microwave Heating Challenges and Controversial Issuesmentioning

confidence: 99%

“…Applying conventional heating in this type of reaction requires quenching or fast cooling the products to avoid undesirable further decompositions. Haneishi et al have demonstrated the temperature distribution of packed catalyst particles under microwave irradiation using the finite element method . Taking advantage of the enormous interaction between microwaves and active catalytic agents in this reaction and the low response of the produced gases to the microwaves can selectively enhance the reaction in a noticeable way.…”

Section: Prospective Microwave Applicationsmentioning

confidence: 99%

The development of industrial (thermal) processes in the context of sustainability: The case for microwave heating

et al. 2020

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The volumetric, uniform, and selective heating of microwaves is a novel technique with the potential to be established in a wide range of applications. The individual interaction of each phase/component of multiphase/multicomponent systems with microwaves creates more than a temperature in the system. Having a high local temperature on an active site that is a strong microwave receptor promotes catalytic and non‐catalytic reactions. The relatively low temperature of the bulk material(s) restricts the undesirable secondary reactions correspondingly. This finding has already led to several applications. In this work, the fundamentals of microwave heating and their prospective applications are debated. Select lab‐scale results of metal and sulphur removal from petroleum oil, pyrolysis of lignin, and dry reforming of methane are demonstrated. The expected impacts of microwaves on other multiphase reactions are proposed.

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“…Microwave (MW) heating processes have been applied to a lot of catalytic reactions [1][2][3][4][5][6][7][8]. In the heterogeneous gas-solid system, solid catalysts are selectively heated due to the interactions of the conduction electrons or the dipoles with MWs [1].…”

Section: Introductionmentioning

confidence: 99%

Drastic Microwave Heating of Percolated Pt Metal Nanoparticles Supported on Al2O3 Substrate

et al. 2020

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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.

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Enhancement of Fixed-bed Flow Reactions under Microwave Irradiation by Local Heating at the Vicinal Contact Points of Catalyst Particles

Cited by 82 publications

References 36 publications

Microwaves and Heterogeneous Catalysis: A Review on Selected Catalytic Processes

Microwaves and Heterogeneous Catalysis: A Review on Selected Catalytic Processes

The development of industrial (thermal) processes in the context of sustainability: The case for microwave heating

Drastic Microwave Heating of Percolated Pt Metal Nanoparticles Supported on Al2O3 Substrate

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