Noise-sustained structures in differential-flow reactors with autocatalytic kinetics

<div>The interface between two immiscible liquids represent an ideal substrate for the assembly of nanomaterials. The defect free surface provides a reproducible support for creating densely packed ordered materials. Here a droplet flow reactor is presented for the synthesis and/ or assembly of nanomaterials at the interface of the emulsion. Each droplet acts as microreactor for a reaction between decamethylferrocene (DmFc) within the hexane and metal salts (Ag+/ Pd2+) in the aqueous phase. The hypothesis was that a spontaneous, interfacial reaction would lead to the assembly of nanomaterials creating a Pickering emulsion. The subsequent removal of the solvents showed how the Ag nanoparticles were trapped at the interface and retain the shape of the droplet, however the Pd nanoparticles were dispersed with no tertiary structure. To further exploit this, a one-step process where the particles are synthesised and then assembled into core-shell materials was proposed. The same reactions were performed in the presence of oleic acid stabilise Iron oxide nanoparticles dispersed within the hexane. It was shown that by changing the reaction rate and ratio between palladium and iron oxide a continuous coating of palladium onto iron oxide microspheres can be created. The same reaction with silver, was unsuccessful and resulted in the silver particles being shed into solution, or incorporated within the iron oxide micro particle. These insights offer a new method and chemistry within flow reactors for the creation of palladium and silver nanoparticles. We use the technique to create metal coated iron oxide nanomaterials but the methodology could be easily transferred to the assembly of other materials.</div><div><br></div>

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Comparison of Isobutane/n-Butenes Alkylation over Y-Zeolite Catalyst in CSTR, Fixed Bed and Circulating Flow Reactors

Review Journal of Chemistry ◽

10.1134/s2079978020010045 ◽

2020 ◽

Vol 10 (1-2) ◽

pp. 58-72

Author(s):

D. A. Sladkovskiy ◽

K. V. Semikin ◽

A. V. Utemov ◽

S. P. Fedorov ◽

E. V. Sladkovskaya ◽

...

Keyword(s):

Zeolite Catalyst ◽

Fixed Bed ◽

Y Zeolite ◽

Flow Reactors

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Simultaneous Kinetics of Selenite Oxidation and Sorption on δ-MnO2 in Stirred-Flow Reactors

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18062902 ◽

2021 ◽

Vol 18 (6) ◽

pp. 2902

Author(s):

Zheyong Li ◽

Yajun Yuan ◽

Lin Ma ◽

Yihui Zhang ◽

Hongwei Jiang ◽

...

Keyword(s):

Rate Constant ◽

Photoelectron Spectroscopy ◽

Oxide Surfaces ◽

Kinetic Rate Constant ◽

Flow Reactors ◽

Mn Oxide ◽

Remediation Strategies ◽

Process Of Se ◽

Kinetics Of

Selenium (Se) is an essential and crucial micronutrient for humans and animals, but excessive Se brings negativity and toxicity. The adsorption and oxidation of Se(IV) on Mn-oxide surfaces are important processes for understanding the geochemical fate of Se and developing engineered remediation strategies. In this study, the characterization of simultaneous adsorption, oxidation, and desorption of Se(IV) on δ-MnO2 mineral was carried out using stirred-flow reactors. About 9.5% to 25.3% of Se(IV) was oxidized to Se(VI) in the stirred-flow system in a continuous and slow process, with the kinetic rate constant k of 0.032 h−1, which was significantly higher than the apparent rate constant of 0.0014 h−1 obtained by the quasi-level kinetic fit of the batch method. The oxidation reaction was driven by proton concentration, and its rate also depended on the Se(IV) influent concentration, flow rate, and δ-MnO2 dosage. During the reaction of Se(IV) and δ-MnO2, Mn(II) was produced and adsorbed strongly on Mn oxide surfaces, which was evidenced by the total reflectance Fourier transform infrared (ATR-FTIR) results. The X-ray photoelectron spectroscopy (XPS) data indicated that the reaction of Se(VI) on δ-MnO2 produced Mn(III) as the main product. These results contribute to a deeper understanding of the interface chemical process of Se(IV) with δ-MnO2 in the environment.

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Towards a Novel Computer-Aided Optimization of Microreactors: Techno-Economic Evaluation of an Immobilized Enzyme System

Symmetry ◽

10.3390/sym13030524 ◽

2021 ◽

Vol 13 (3) ◽

pp. 524

Author(s):

Philip Pietrek ◽

Manfred Kraut ◽

Roland Dittmeyer

Keyword(s):

Magnetic Beads ◽

Glucose Dehydrogenase ◽

Packed Bed ◽

Detailed Knowledge ◽

Reaction Conditions ◽

Flow Reactors ◽

Continuous Flow Reactors ◽

Enzyme Cascades ◽

And Control ◽

Physical And Chemical

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.

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