Examples for Microreactor Applications

The exploration of new process regimes is tightly correlated to the task of chemical production [3, 8, 25]. Microreactors will then not only serve to investigate processes of macroreactors under ideal or otherwise not feasible conditions, but are expected to partially replace macroreactors for different applications. An example for a reaction which can hardly be achieved even on a laboratory scale is the direct fluorination of aromatics. 

The stable encapsulation of biological cargo is important for applications in drug delivery. However, for some applications, enhanced permeability can be advantageous, for example in the design of microreactors. In this case, diffusion of low molecular weight species can initiate and maintain reactions occurring inside the capsule (see Sect. 4). 

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]. 

A general application area of microreactors is screening. Screening applications have been described, for example, for catalyst search in the area of heterogeneously catalyzed gas-phase reactions [23] and homogeneously catalyzed gas-liquid reactions and for parameter screenings in process development. 

Microreactor Technology In the last years, some examples of Radziszewski reaction have been reported using microreactor technology, which allows the development of more sustainable methods thanks to the miniaturization and increased safety and efficiency [60, 61]. In particular, the Stevens and the Orru groups developed in cooperation a procedure for the continuous production of highly substituted imidazoles [62, 63]. They were motivated by the possibility of making the method previously reported by Orra [64] more interesting for industrial applications. The latest procedure... 

Nowadays, catalytic microreactors for gas phase reactions have become established as tools for laboratory and pilot scale investigations. The first examples of microreactors becoming established in chemical production have been published, but many other applications are being kept proprietary. Microreactors are heading for... 

---