Single-channel microreactor

Microreactor scale-up is built upon the premise of numbering up channels. Figure 11.1. A single channel is demonstrated with the same geometry and fluid hydrodynamics as a full-scale reactor. Numbering up rehes on creating a massively... 

Figure 4.33 Schematic of the single-channel microreactor used for fluorinations with elemental fluorine (by courtesy of the Royal Society of Chemistry) [272].

The microreactor contained a single channel with two feeds for gas and liquid [309,273]. The gas flows were set so high that an annular-flow regime was reached with a central gas core surrounded by a liquid film wetting the channel. This flow pattern has a very high interface and low liquid-side resistance due to the thin film. Formic acid was used as a solvent. 

The performance of a single-channel and a numbered-up three-channel microreactor was similar [273]. Some differences were found that probably originate more from fluctuations in the hydrodynamics than from the numbering up. 

The oxidation of cyclohexanol to cyclohexanone with fluorine and aqueous acetonitrile was performed in a single-channel microreactor operated under annular flow at room temperature. A conversion of 84% and a selectivity of 74% were observed [313], In a similar way, diols such as 1,2-cyclohexanediol were partly or fully oxidized. A 53% selectivity to the monooxidation product was obtained at a conversion of 87% the dioxidation product was obtained with 30% yield. 

FIGURE 23 Scheme of a single channel microreactor for methane steam reforming [182]. (Adapted with permission from Elsevier.)... 

To eliminate uncertainties associated with distribution of the reaction mixture to multiple parallel microchannels, and to eliminate associated axial dispersion in the necessary distribution and collection headers, a single channel microreactor was constructed of commercially available tubing. The criteria that governed the selection of the reactor and other tubing dimensions included ... 

Our ultimate vision was to automate the reactor scale-up process, from experimental design through the development of mathematical models of reaction kinetics. To achieve this vision, we chose to first demonstrate that a custom, single channel microreactor could be used to generate quantitative scale-up data. 

DifTerent types of microreactors, ranging from single-channel to multi-channel designs, and even more complex falling film reactors, have been investigated for carrying out photochemical reactions. Reported channel dimensions of photomicroreactors range from 10 to 1000 pm. 

Figure 1.1 Microreactors (40 mm x 15 mm x 1.0-1.5 mm) for gas-liquid-solid Pt-catalyzed cyclohexene hydrogenation at room temperature (a) single-channel and (b) 10 parallel channel configuration, (a) Reprinted with permission from [18], Copyright 2001 American Chemical Society (b) reproduced from [19] with permission, Copyright 2002 IEEE.

Single channel microreactor Three channel microreactor... 

Perfluorination of tetrahydrofuran and cyclohexane derivatives can be achieved to give the perfluorinated product in high yield (Scheme 8.6). These hazardous perfluorination processes can be carried out safely in single-channel microreactors with high yields. 

Both reactor types R3 and R4 use the segmented flow (Taylor) principle. They are divided into two categories R3 has very small channels (<1 mm) and R4 are monolith reactors (honeycomb), well developed on the laboratory scale with at least one example of industrial application. Category R3 includes single-channel and multi-ple-channel reactors [10], etched in silicon [10] or glass [10,11], with wall-coated or immobilized catalysts in the case of gas-liquid-solid additions [12], and capillary microreactors for gas-liquid-liquid systems [13]. 

C. de Bellefon, T. Lamouille, N. Pestre, F. Bornette, H. Pennemann, F. Neumann, V. Hessel, Asymmetric catalytic hydrogenations at micro-litre scale in a helicoidal single channel falling film microreactor, Catal. Today 2005, 110, 179-187. 

Figure 25.3 Single-channel microreactor covered with Pyrex glass (heating element not visible) filled with 0.1 wt.% rhodium on alumina [8].

FFMR, falling film microreactor PBMR, packed-bed microreactor MM, micromixer MBC, microbubble column MMR, microstructured mesh reactor SCR, single-channel reactor... 

Hydrolytic processes in continuous-flow were investigated not only on a preparative scale. For example, a miniaturized single channel microreactor was applied for KR of 2-(phenoxymethyl) oxirane to screen the enantiomer selectivity of epoxy hydrolases created by directed evolution [98]. 

Compared to batch and single-channel microreactors, the results clearly demonstrate that the daily output can considerably be increased by application of the scaled-up dual-channel microreactor. In the next step, the dual-channel reactor was applied for the photosensitized oxidation of aDyUc alcohols 99 (Figure 6.48). The corresponding products, aUyl hydroperoxide alcohols 100, can be employed for the synthesis of artemisinin-derived antimalarial 1,2,4-trioxanes. The... 

The process of wet-chemical etching of single-crystalline silicon was the first process suitable for the mass fabrication of micromechanical components [53]. Simple geometric structures like grooves, channels or membranes have been incorporated in microreactor components such as pumps, valves, static mixers and (most often) analytical devices. Bonding processes, either thermally or... 

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