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Symmetry
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Symmetry and Complexity of Catalysis in Flow Chemistry
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Symmetry and Complexity of Catalysis in Flow Chemistry

A special issue of Symmetry (ISSN 2073-8994). This special issue belongs to the section "Chemistry: Symmetry/Asymmetry".

Deadline for manuscript submissions: closed (31 January 2022) | Viewed by 18608

Special Issue Editors

Prof. Dr. Wladimir Reschetilowski

E-Mail Website
Guest Editor
Fakultät Chemie und Lebensmittelchemie, Technische Universität Dresden, Helmholtzstraße 14, 01069 Dresden, Germany
Interests: heterogeneous catalysis; zeolites; micro/mesoporous aluminosilicates; microreactor systems; flow chemistry; green chemistry
Special Issues, Collections and Topics in MDPI journals
Dr. Ekaterina Borovinskaya

E-Mail Website
Guest Editor
University of Technology Dresden/Saint-Petersburg State Institute of Technology (Technical University)
Interests: microreactor systems; catalysis processes; modeling and optimization

Special Issue Information

Dear Colleagues,

Flow microreactor systems are used in many chemical processes, from simple homogeneous conversions to complex catalytic and biochemical reactions. Their advantages are based on extremely small dimensions of reactor channels in the range from some micrometers to a few millimeters. This reduces the diffusion length and the mixing time in comparison with conventional reactors and provides better process control and safety. Special types of microreactors are created for different types of systems to ensure the greatest intensification of chemical processes. Especially, the spatial microfluidics symmetry and complexity of the reaction system used is always taken into account. Their main advantages are the improvement of the flow pattern and the intensification of mass and heat transfer as well as of the interaction between reactants at the molecular level. The aim of this Special Issue is, therefore, to cover recent advances in the field of the flow microreactor systems for a wide range of applications, including homogeneous and heterogeneous catalyzed reactions, polymer reactions, syntheses by means of biocatalysts, electrocatalysts, photocatalysts, and also nanotechnology and microwave-, plasma-, or tribochemical-activated reactions. We kindly invite you to contribute to the Special Issue with an emphasis on investigations of the effect of microscale applied fields dealing with symmetry and complexity of catalysis in flow chemistry.

Prof. Wladimir Reschetilowski
Dr. Ekaterina Borovinskaya
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. Symmetry 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

  • Microreactor
  • Micromixing
  • Symmetry and complexity of microfluidics
  • Symmetry and complexity of homogeneous catalysis
  • Symmetry and complexity of heterogeneous catalysis
  • Symmetry and complexity of polymer synthesis
  • Symmetry and complexity of organocatalysis
  • Symmetry and complexity of biocatalysis
  • Symmetry and complexity of electrocatalysis
  • Symmetry and complexity of photocatalysis
  • Symmetry and complexity of nanotechnology
  • Symmetry and complexity of plasma-activated reactions
  • Symmetry and complexity of microwave-activated reactions
  • Symmetry and complexity of tribochemical activated reactions
  • Symmetry and complexity of reaction networks
  • Modeling of complex chemical reactions
  • Optimization of complex chemical reactions
  • Computing applications in flow chemistry

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Published Papers (6 papers)

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Research

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20 pages, 5008 KiB  
Article
Towards a Novel Computer-Aided Optimization of Microreactors: Techno-Economic Evaluation of an Immobilized Enzyme System
by Philip Pietrek, Manfred Kraut and Roland Dittmeyer
Symmetry 2021, 13(3), 524; https://doi.org/10.3390/sym13030524 - 23 Mar 2021
Cited by 2 | Viewed by 3113
Abstract
Immobilized multi-enzyme cascades are increasingly used in microfluidic devices. In particular, their application in continuous flow reactors shows great potential, utilizing the benefits of reusability and control of the reaction conditions. However, capitalizing on this potential is challenging and requires detailed knowledge of [...] Read more.
Immobilized multi-enzyme cascades are increasingly used in microfluidic devices. In particular, their application in continuous flow reactors shows great potential, utilizing the benefits of reusability and control of the reaction conditions. However, capitalizing on this potential is challenging and requires detailed knowledge of the investigated system. Here, we show the application of computational methods for optimization with multi-level reactor design (MLRD) methodology based on the underlying physical and chemical processes. We optimize a stereoselective reduction of a diketone catalyzed by ketoreductase (Gre2) and Nicotinamidadenindinukleotidphosphat (NADPH) cofactor regeneration with glucose dehydrogenase (GDH). Both enzymes are separately immobilized on magnetic beads forming a packed bed within the microreactor. We derive optimal reactor feed concentrations and enzyme ratios for enhanced performance and a basic economic model in order to maximize the techno-economic performance (TEP) for the first reduction of 5-nitrononane-2,8-dione. Full article
(This article belongs to the Special Issue Symmetry and Complexity of Catalysis in Flow Chemistry)
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21 pages, 5570 KiB  
Article
Intermediate Gas Feed in Bi- or Triphasic Gas–Liquid(–Liquid) Segmented Slug Flow Capillary Reactors
by Niclas von Vietinghoff, David Hellmann, Jan Priebe and David W. Agar
Symmetry 2020, 12(12), 2092; https://doi.org/10.3390/sym12122092 - 16 Dec 2020
Cited by 3 | Viewed by 2312
Abstract
Segmented slug flow systems in capillaries have already shown good potential for process intensification, due to their symmetry in the characteristic flow pattern. However, several challenges remain in this technology. For instance, in gas-consuming reactions, like Aliq + Bgas→Cliq [...] Read more.
Segmented slug flow systems in capillaries have already shown good potential for process intensification, due to their symmetry in the characteristic flow pattern. However, several challenges remain in this technology. For instance, in gas-consuming reactions, like Aliq + Bgas→Cliq, the gas droplets shrink and may even disappear, limiting the conversions and throughputs of capillary reactor systems. To overcome such shortcomings, an intermediate gas feed was developed. In order to maintain the well-defined slug flow characteristics, it is necessary to introduce the gas rapidly and precisely, in small aliquots of <10 µL. This allows us to preserve the well-defined alternating triphasic slug flow. A miniaturized electrolysis cell, together with a flow-observing system, was thus devised and implemented successfully as an intermediate gas feed. Feeding a new gas droplet into an existing liquid–liquid segmented flow had a success rate of up to 99%, whereas refilling an existing gas droplet is often limited by a lack of coalescence. Here, only at low volumetric flows, 70% of the gas bubbles were refilled by coalescence. Full article
(This article belongs to the Special Issue Symmetry and Complexity of Catalysis in Flow Chemistry)
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7 pages, 211 KiB  
Article
Single-Route Linear Catalytic Mechanism: A New, Kinetico-Thermodynamic Form of the Complex Reaction Rate
by Gregory S. Yablonsky, Denis Constales and Guy B. Marin
Symmetry 2020, 12(10), 1748; https://doi.org/10.3390/sym12101748 - 21 Oct 2020
Cited by 5 | Viewed by 2045
Abstract
For a complex catalytic reaction with a single-route linear mechanism, a new, kinetico-thermodynamic form of the steady-state reaction rate is obtained, and we show how its symmetries in terms of the kinetic and thermodynamic parameters allow better discerning their influence on the result. [...] Read more.
For a complex catalytic reaction with a single-route linear mechanism, a new, kinetico-thermodynamic form of the steady-state reaction rate is obtained, and we show how its symmetries in terms of the kinetic and thermodynamic parameters allow better discerning their influence on the result. Its reciprocal is equal to the sum of n terms (n is the number of complex reaction steps), each of which is the product of a kinetic factor multiplied by a thermodynamic factor. The kinetic factor is the reciprocal apparent kinetic coefficient of the i-th step. The thermodynamic factor is a function of the apparent equilibrium constants of the i-th equilibrium subsystem, which includes the (n−1) other steps. This kinetico-thermodynamic form separates the kinetic and thermodynamic factors. The result is extended to the case of a buffer substance. It is promising for distinguishing the influence of kinetic and thermodynamic factors in the complex reaction rate. The developed theory is illustrated by examples taken from heterogeneous catalysis. Full article
(This article belongs to the Special Issue Symmetry and Complexity of Catalysis in Flow Chemistry)
8 pages, 1336 KiB  
Article
Prediction in Chaotic Environments Based on Weak Quadratic Classifiers
by Alexander Musaev and Ekaterina Borovinskaya
Symmetry 2020, 12(10), 1630; https://doi.org/10.3390/sym12101630 - 2 Oct 2020
Cited by 3 | Viewed by 2447
Abstract
The problem of prediction in chaotic environments based on identifying analog situations in arrays of retrospective data are considered. Traditional recognition schemes are ineffective and form weak classifiers in cases where the system component of the observed process is represented by a non-periodic [...] Read more.
The problem of prediction in chaotic environments based on identifying analog situations in arrays of retrospective data are considered. Traditional recognition schemes are ineffective and form weak classifiers in cases where the system component of the observed process is represented by a non-periodic oscillatory time series (realization of chaotic dynamics). The objective is to develop a system of such classifiers, which allows for improvements in the quality of forecasts for non-stationary dynamics in flow processes. The introduced technique can be applied for the prediction of oscillatory non-periodic processes with non-stationary noise, i.e., dependence of different relay frequencies, external electric potential and microchannel width in an electrokinetic micromixer. Full article
(This article belongs to the Special Issue Symmetry and Complexity of Catalysis in Flow Chemistry)
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14 pages, 2519 KiB  
Article
Enzymatic Degradation of 2,4,6-Trichlorophenol in a Microreactor using Soybean Peroxidase
by Rodrigo A. Costa, Alexandre S. Cunha, José Carlos G. Peres, Adriano R. Azzoni, Enzo Laurenti and Ardson S. Vianna, Jr.
Symmetry 2020, 12(7), 1129; https://doi.org/10.3390/sym12071129 - 7 Jul 2020
Cited by 2 | Viewed by 2348
Abstract
Soybean peroxidase is an enzyme extracted from soybean seed hulls. In the presence of hydrogen peroxide, the enzyme has the potential to catalyze the biodegradation of toxic substances like chlorophenols. For this reason, its use in wastewater treatment processes is environmentally friendly since [...] Read more.
Soybean peroxidase is an enzyme extracted from soybean seed hulls. In the presence of hydrogen peroxide, the enzyme has the potential to catalyze the biodegradation of toxic substances like chlorophenols. For this reason, its use in wastewater treatment processes is environmentally friendly since the enzyme can be obtained from a renewable and abundant raw material. In this work, enzymatic biodegradation of 2,4,6-trichlorophenol performed by soybean peroxidase in a microreactor was studied experimentally and theoretically. The experimental data set was obtained with a volume of 250 μL by using different soybean peroxidase concentrations and different reaction times. The fluid dynamics of the microreactor was modeled as well, using ANSYS CFX. The simulations exhibited secondary flows, which enhanced mixing. Although the laminar flow was developed, it can be assumed to be a well-mixed medium. The kinetic data were evaluated through a mechanistic model, the modified bi-bi ping-pong model, which is adequate to represent the enzymatic degradation using peroxidases. The model was composed of an initial value problem for ordinary differential equations that were solved using MATLAB. Some kinetic constants were estimated using the least square function. The results of the model fit well the experimental data. Full article
(This article belongs to the Special Issue Symmetry and Complexity of Catalysis in Flow Chemistry)
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Review

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18 pages, 4793 KiB  
Review
Continuous-Flow Photocatalytic Microfluidic-Reactor for the Treatment of Aqueous Contaminants, Simplicity, and Complexity: A Mini-Review
by Zhongwei Gao, Changqing Pan, Chang-Ho Choi and Chih-Hung Chang
Symmetry 2021, 13(8), 1325; https://doi.org/10.3390/sym13081325 - 23 Jul 2021
Cited by 16 | Viewed by 5007
Abstract
Water pollution is a growing global issue; there are many approaches to treating wastewater, including chemical coagulation, physical adsorption, and chemical oxidation. The photocatalysis process has provided a solution for removing pollutants from wastewater, where the pair of the photoelectron and hole works [...] Read more.
Water pollution is a growing global issue; there are many approaches to treating wastewater, including chemical coagulation, physical adsorption, and chemical oxidation. The photocatalysis process has provided a solution for removing pollutants from wastewater, where the pair of the photoelectron and hole works through an asymmetric way to degrade the contaminants under UV irradiation. This method offers an alternative route for treating the pollutant with a lower energy cost, high efficiency, and fewer byproducts. A continuous-flow microfluidic reactor has a channel size from tens to thousands of micrometers, providing uniform irradiation and short diffusion length. It can enhance the conversion efficiency of photocatalysis due to the simple spatial symmetry inside the microreactor channel and among the individual channels. In addition, the bandgap of TiO2, ZnO, or other photocatalyst nanoparticles with symmetric crystal structure can be modified through doping or embedding. In this mini-review, a review of the reported continuous-flow photocatalytic microfluidic reactor is discussed from the perspective of both microreactor design and material engineering. Full article
(This article belongs to the Special Issue Symmetry and Complexity of Catalysis in Flow Chemistry)
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