Surface heating and energy transfer in pulsed microwave catalytic systems: A microwave-induced acoustic study

Wan, J. K. S.; Ioffe, M. S.

doi:10.1163/156856794x00126

Cited by 19 publications

(8 citation statements)

References 12 publications

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“…This opens up the possibility of using the coupling to microwaves of one component in a mixture to drive a chemical reaction with a second component which may be transparent to microwaves . The desired chemical selectivity in the products is typically achieved by appropriate microwave pulsing as well as changing the material used as a sensitizer. − ,− …”

Section: Discussionmentioning

confidence: 99%

Effect of Dielectric Constant, Cavities in Series, and Cavities in Parallel on the Product Distribution of the Oligomerization of Methane via Microwave Plasmas

et al. 1996

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The use of microwave-induced plasmas as a method to oligomerize methane to higher hydrocarbons has been studied. The pressure range used was 10−20 Torr and the applied power was 60 W. The microwave power is coupled to the plasma by means of either an Evenson or a Beenakker cavity, the Beenakker being the most effective. We explored the effect of the presence of a dielectric material on the product distribution for this reaction. The values of the dielectric constants for these materials varied from 2.6 for Pb(Ac)2 to 10 000 for MnO2 relative to the vacuum. No direct correlation was found, but in some cases the selectivities toward C6s to C8s were enhanced. TiO2 and Li2CO3 increased the selectivities toward C6s. SnO2 was the best for selectivities to C7s and C8s. When a coating of Si/SiC on the reactor walls was present in the plasma zone, the selectivities toward C6s and C7s increased with respect to both materials (Si and SiC) by themselves. We also studied the effect of cavities in series and cavities in parallel on the oligomerization of methane with and without dielectric material in between the cavities. When methane and iodine are activated separately and then recombined, it seems that the oligomerization of methane is enhanced toward higher hydrocarbons. We found that when a dielectric material is placed in between and when the distance between the two cavities in series is the largest, the oligomerization of methane toward high molecular weight hydrocarbons is maximized.

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Section: Discussionmentioning

confidence: 99%

Effect of Dielectric Constant, Cavities in Series, and Cavities in Parallel on the Product Distribution of the Oligomerization of Methane via Microwave Plasmas

et al. 1996

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“…The influence of both the microwave frequency and pulsed microwave irradiation was considered; optimal reaction conditions were determined in the presence of a solid catalyst. 13 Of particular interest were catalysts that absorbed microwave radiation, and not least was the notion of differential heating in the quality of a reaction group that involved formation of hot spots on the catalyst surface. Accordingly, the next section examines selective heating of a heterogeneous catalyst (metallic or organic catalyst) by the microwaves.…”

Section: Catalysis Science and Technology Minireviewmentioning

confidence: 99%

“…Temperatures reached following 2 min pulsed microwave irradiation of some substrates are collected in Table 1 for catalyst and catalyst support powders 13 note that the heating efficiency depends, among other factors, on the presence of oxygen vacancies, on particle size, and on the crystal structure of the materials. The efficiency of heating is influenced by the composition of the metal oxide particles.…”

Section: Catalysis Science and Technology Minireviewmentioning

confidence: 99%

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Role of microwaves in heterogeneous catalytic systems

Horikoshi

Serpone

2014

Catal. Sci. Technol.

144

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“…The article presents an application for a simple and efficient effectively 1D approach for the solution of a 3D problem. Note that quite similar 1D approaches where considered in the literature to study, e.g., complex transients in pulsed OA spectroscopy [16], surface heating and energy transfer in pulsed microwave catalytic systems [17], and, thin-film piezoelectric ultrasonic sensors [18].…”

Section: Introductionmentioning

confidence: 99%

Numerical prediction of the piezoelectric transducer response in the acoustic nearfield using a one-dimensional electromechanical finite difference approach

Melchert¹,

Blumenröther²,

Meinhardt‐Wollweber³

et al. 2017

Preprint

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We present a simple electromechanical finite difference model to study the response of a piezoelectric polyvinylidenflourid (PVDF) transducer to optoacoustic (OA) pressure waves in the acoustic nearfield prior to thermal relaxation of the OA source volume.The assumption of nearfield conditions, i.e. the absence of acoustic diffraction, allows to treat the problem using a one-dimensional numerical approach. Therein, the computational domain is modeled as an inhomogeneous elastic medium, characterized by its local wave velocities and densities, allowing to explore the effect of stepwise impedance changes on the stress wave propagation. The transducer is modeled as a thin piezoelectric "sensing" layer and the electromechanical coupling is accomplished by means of the respective linear constituting equations. Considering a low-pass characteristic of the full experimental setup, we obtain the resulting transducer signal. Complementing transducer signals measured in a controlled laboratory experiment with numerical simulations that result from a model of the experimental setup, we find that, bearing in mind the apparent limitations of the one-dimensional approach, the simulated transducer signals can be used very well to predict and interpret the experimental findings.

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Surface heating and energy transfer in pulsed microwave catalytic systems: A microwave-induced acoustic study

Cited by 19 publications

References 12 publications

Effect of Dielectric Constant, Cavities in Series, and Cavities in Parallel on the Product Distribution of the Oligomerization of Methane via Microwave Plasmas

Effect of Dielectric Constant, Cavities in Series, and Cavities in Parallel on the Product Distribution of the Oligomerization of Methane via Microwave Plasmas

Role of microwaves in heterogeneous catalytic systems

Numerical prediction of the piezoelectric transducer response in the acoustic nearfield using a one-dimensional electromechanical finite difference approach

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