Micromixer high-pressure

Figure 4.42 High-pressure interdigital micromixer made of steel (by courtesy of IMM).

Process development was performed at laboratory scale using a slit-type interdigital micromixer-reactor, which was later replaced by a special high-pressure interdigital micromixer [12]. The mixers are followed by a cartridge filled with catalyst, which acts as mini-trickle bed. Many further plant details have been developed for the safe operation of the hazardous process gas mixture, but remain undisclosed. 

The reactants were contacted in a high-pressure interdigital micromixer followed by a capillary reactor, all immersed in an oil bath [45,46]. Pure bromine and pure aromatic were fed, mixed and reacted. By a high-temperature, high-pressure (high-p,T) route, the side-chain bromination of meta-nitrotoluene was achieved. This allows one to extend the operational range much beyond the boiling point, which is the technical limit of many reactions carried out batchwise. 

An interdigital slit-type high-pressure micromixer followed by a tube (0.9 mm inner diameter 2.6 m long) was used [48]. The micromixer-tube reactor was submersed into a thermostat bath for temperature setting. HPLC pumps fed the monomer and initiator flows. A back-pressure cartridge (70 bar) and a pressure sensor served for pressure control. The temperature was set to 105 °C. The processing protocol was carried out conventionally, using the specs of similar batch processes. 

Table 6.4 Performance data for the free-radical polymerization of styrene at two monomer concentrations. The behavior of three reactors is compared - flask, T-junction (Tj), and high-pressure interdigital micromixer (HPIMM) by experiment and by modeling [49].

Continuous nitroxide-mediated block copolymerization of n-butyl acrylate (first monomer) and styrene (second monomer) can be performed using two serial 900-p m inner diameter stainless steel microtube reactors (Fig. 29) [215]. For the second polymerization process, the influence of mixing was examined by changing micromixers. The use of a high-pressure interdigital multilamination micromixer (HPIMM) provided by the Institut fiir Mikrotechnik Mainz (Mainz, Germany), can significantly reduce the polydispersity index = 1.36, 120°C) compared... 

Optimizing the efficiency of droplet formation, disintegration and stabilization is the domain of microengineered devices. Here, micromixers, optimized high-pressure homogenizer nozzles and specific microfluidic devices such as microchannels are under investigation. 

The capillary micromixer has proven to be a fast and versatile mixing device. The great advantage of the capillary micromixers are the short dead time while operating at low pressures. The small observation volume so far precludes application of, for example, UV-Vis absorbance spectroscopy, for which the sample requirements are relatively high. 

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