Interdigital mixer

Molar ratios of bromine to m-nitrotoluene ranging from 0.25 to 1.00 were applied. The reactants were contacted in an interdigital micro mixer followed by a capillary reactor. At temperatures of about 200°C nearly complete conversion is achieved (see Fig. 6). The selectivity to the target product benzyl bromide is reasonably high (at best being 85% at 200°C and higher being 80%). The main sideproduct formed is the nitro-substituted benzal bromide, i.e. the two-fold brominated side-chain product. 

Figure 1.19 Semi-analytical calculation of the speed of mixing in an advanced interdigital micro mixer, named SuperFocus, and comparison with previously developed interdigital micro mixers [120],...

Figure 1.20 Periodic concentration profile of a regular multi-lamellar pattern in a rectangular interdigital micro mixer, determined by photometric-type analysis [119].

Reactor 9 [R 9] Chip System with Triangular Interdigital Micro Mixer-Reaction Channel... 

This system is a chip version of three dimensional micro mixer-tube reactor setups [21]. It comprises a triangular interdigital micro mixer with a focusing zone that thins the multi-lamellae and a subsequent reaction channel that is surrounded... 

Figure4.9 Chip system with triangular interdigital micro mixer-reaction channel. First- (top) and second- (bottom) generation reactor designs [22],...

Right cut through the top part of the housing of the slit interdigital 3-D micro mixer comprising the slit-type focusing zone and the subsequent small channel to the outlet [40, 41). 

Figure 4.19 SEM of the feed part of a 2-D rectangular interdigital micro mixer [44].

Reactor 19 [R 19] Slit-Type Interdigital Micro Mixer-Tube Reactor... 

Interdigital micro mixers comprise feed channel arrays which lead to an alternating arrangement of feed streams generating multi-lamellae flows [39 2]. If processes have to be carried out with extended residence times (> 1 s) and/or at a temperature level different from the mixing step, tubes have to be attached to the interdigital micro mixers. Their internals comprise millimeter dimensions or below, if necessary. 

Figure 4.20 Schematic of laboratory-scale reaction system with a slit-type interdigital micro mixer as central element, used at Merck site [134],...

One version of this reactor concept is the combination of the triangular interdigital metal/steel micro mixer (for a detailed description, see [R 18]) vhth conventional PTFE tubing (Figure 4.21) [46, 48]. 

Figure 4.21 Flow sheet of a laboratory triangular interdigital micro mixer-tube reactor set-up, used for an industrial application, the so-called Clariant process [4Xj.

Reactor type Triangular interdigital micro Mixer material Specialty glass (Foturan )... 

Figure 4.37 Images of contacting sulfuric acid with dyed (iodine) toluene in a rectangularshaped interdigital micro mixer at two different flow rates. The system sulfuric acid/toluene (iodine) was taken as model for the reacting media sulfuric acid/benzal chloride [46. ...

Figure 4.38 Increase in benzaldehyde yield with increase in reaction temperature by performing benzal chloride hydrolysis in a slit-shaped interdigital micro mixer [46].

OS 1] [R 20] [P 1] A comparison of the selectivity/conversion behavior of an interdigital micro mixer-tube reactor with that of a mixing tee of about 1.5 mm inner diameter (and thus of larger internal dimensions) was made (Figure 4.39). For all data gathered, the performance of the micro mixer was much better, e.g. about 30% more selectivity at a given conversion [46]. 

P 28] A glass interdigital micro mixer was connected to PTFE tubes with an inner diameter of 2 mm which was immersed in an ice-water bath of appropriate temperature (laboratory set-up) [48, 108]. Operation was performed for 5-40 s at temperatures ranging from -12 to 50 °C. 

OS 40] [R 20] [P 28] The best yield obtained in the interdigital micro-mixer laboratory-scale set-up was 83% (22 °C 1000 ml h 8 s) ]48]. Compared with the performance of the industrial production process (65%, batch), this is an improvement of nearly 20%. Most experiments done at widely different residence time and reaction temperature did not differ from this best yield by more than 5-10%. 

OS 40] ]R 20] ]P 28] Using an interdigital micro mixer, a nearly constant yield could be obtained for the full range of residence times at 22 and 50 °C (5 0 s) [48]. At lower temperature (-12 °C), a maximum yield at a flow rate of 1000 ml h (5 s) is obtained. Still higher flow rates lead to a too low residence time (Figure 4.60). 

Figure 4.60 Yield of product and side/consecutive products as a function of flow rate, respectively residence time for the laboratory set-up with an interdigital micro mixer [48],...

OS 41a] [R 19] ]P 30] A study was undertaken to compare extended (1 h) processing in small vials (2 cm ) with short-time (100 s) continuous micro reactor and mini-batch (10 cm ) operation for 10 different substrates (C4-C8 alcohols) which were reacted with rhodium(I)-tris(m-sulfophenyl)phosphane [111]. The vials were either directly filled with the two phases yielding a bilayered fluid system with small specific interfaces or by interdigital micro mixer action yielding an emulsion with large specific interfaces. 

Figure 4.73 Schematic of laboratory-scale experimental set-up for polyacrylate formation. The Sulzer-type pre-mixer can be replaced by an interdigital micro mixer [125].

In turn, the interdigital micro mixer mixes much faster, provides more unique concentration profiles before reaction takes place and consequently changes the course of the reaction [125]. As a result, no high-molecular-weight polymer fraction is observed by GPC measurement and no fouling occurs, although the specific wall surfaces of the micro device are expected to promote deposition. 

OS 63] [R 27] [R 18] [P 46] Using a slit-type interdigital micro mixer prior to a liquid/liquid reaction system improves the conversion to 80%, hence close to the kinetic limits [117]. This is an improvement over using a microgrid in front of the reactor (see the Section Conversion/selectivity/yield - benchmarking to batch processing/kinetics, above). 

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