Dual-channel microreactor

Figure 4.34 Schematic of the inlet section of the dual-channel microreactor (bottom) and scanningelectron micrograph of a cut through the dual-channel section (top) (by courtesy of American Chemical Society) [274].

Figure 4.35 Flow pattern map for the nitrogen/ acetonitrile flow in the dual-channel microreactor. Annular flow wavy annular flow (WA) wavy annular-dry flow, (WAD) slug flow bubbly flow annular-dry flow (AD). Transition lines for nitrogen-acetonitrile flows in a triangular channel (224 pm) (solid line). Transition lines for air-water flows in triangular...

As a result of the increased illumination as well as the increased gas-liquid contact area per unit volume, the triple-channel microreactor exhibited better performance compared to the batch reactor, or even compared to a typical dual-channel microreactor [138,139]. Moreover, the scaleup process using the microreactor revealed higher productivity than the batch reactor, which would be valuable for the practical applications in a broad range of gas-liquid chemical reactions. 

Table 6.4 In situ diazomethane generation, separation, and conversion in the dual-channel microreactor at room temperature.

The photooxygenation of citronellol (93) was also studied by Park et al. [44]. In this work, different types of reactors were compared regarding the gas-hquid contact area and their performance in photooxygenation reactions. In this context, the authors developed a transparent dual-channel microreactor. The potential of dual-channel microreactors designed by Kim et al. has already been described in Section 6.2.2. 

Figure 6.47 Schematic illustration of photosensitized oxygenation in a dual-channel microreactor shielded with solvent-resistant coating. (Reproduced from Ref [44] with permission of the Royal Society of Chemistry.)...

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... 

With the use of falling-film microreactor or a microbubble column, yields of up to 28% were obtained with acetonitrile as solvent at conversions ranging from 7 to 76% and selectivities from 31 to 43% with regard to the monofluorinated product [308]. With the use of dual-channel reactor, conversions from 17 to 95% and selectivities from 37 to 10% were achieved using methanol as solvent [274]. The conversion of a laboratory bubble column, taken for comparison, ranged from 6 to 34% with selectivities of 17-50%, which is equivalent to yields of 2-8% [308],... 

The heart of the system is a microreactor packaging scheme that is based upon a commercially available microchip socket. This approach allows the silicon-based reactor die, which contains dual parallel reaction channels with more than 100 electrical contacts, to be installed and removed in a straightforward fashion without removing any fluidic and electronic connections. Various supporting microreactor functions, such as gas feed flow control, gas feed mixing, and various temperature control systems, are mounted on standard CompactPCI electronic boards. The boards are subsequently installed in a commercially available computer chassis. Electrical connections between the boards are achieved through a standard backplane and custom-built input-output PC boards. A National Instruments embedded real-time processor is used to provide closed-loop process control and... 

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