Laboratory microreactor processing

The increased interfacial area in the microreactor led to an increased pressure drop. The energy dissipation factor, the power unit per reactor volume, of the microreactor process was thus higher (sv = 2-5 kW/m3) than that of the laboratory trickle-bed reactors (sv = 0.01-0.2 kW/m3) [277]. This is, however, outperformed by the still larger gain in mass transfer so that the net performance of the microreactor is better. 

Microreactor processing was revised by comparison with traditional means at a laboratory level [11,14]. 

Fig. 6.18 Flow sheet of the laboratory-scale microreactor configuration of the phenyl boronic acid microreactor process, equipped with an interdigital micromixer. (Courtesy of the American Chemical Society [30].)...

Microreactor Laboratory-scale Process Developments for Future Industrial Use... 

Microreactor Laboratory-scale Process Developmentsfor Future Industrial Use I 111... 

A variety of microreactors for liquid-liquid reactions are available and have been described in literature. The adopted throughputs start from below the mLh level for analytical purposes. Micromixers for laboratory-scale process development or organic synthesis can handle flows from mLh to Lh . For the range from above 10 Lh up to tens of m h microstructured mixers are also available and some are already in production use. 

Figure 9.29 Reduction of reaction times by as given in Ref. [119]) as compared to standard several orders of magnitude using a falling film organic laborato processing with a laboratory microreactor (FFMR) or micro bubble columns bubble column (LBC). x residence time. Source (MBC I and II, denoting different dimensions, By courtesy of I MM.

The same features were found for pilot-size microreactor operation (see Figure 11.33). Brightness and transparency were the same, and the color strength could even be increased to 149% [91]. The mean particle size was even smaller as compared to the laboratory-scale microreactor processing (microreactor D50 = 90 nm, s = 1.5 batch 050=600 nm, s=2.0), probably due to process optimization. 

Stainless steel is the material of choice for process chemistry. Consequently, stainless steel microreactors have been developed that include complete reactor process plants and modular systems. Reactor configurations have been tailored from a set of micromixers, heat exchangers, and tube reactors. The dimensions of these reactor systems are generally larger than those of glass and silicon reactors. These meso-scale reactors are primarily of interest for pilot-plant and fine-chemical applications, but are rather large for synthetic laboratories interested in reaction screening. The commercially available CYTOS Lab system (CPC 2007), offers reactor sizes with an internal volume of 1.1 ml and 0.1 ml, and modular microreactor systems (internal reactor volumes 0.5 ml to... 

Hessel V, Hofmann C, Lob P, Lohndorf J, Lowe H, Ziogas A (2005) Aqueous Kolbe-Schmitt synthesis using resorcinol in a microreactor laboratory rig under high-P,T conditions. Org Process Res Dev 9 479-489 Inoue T, Schmidt MA, Jensen KF (2007) Microfabricated multiphase reactors for the direct synthesis of hydrogen peroxide from hydrogen and oxygen. Ind Eng Chem Res 46 1153-1160... 

The modern methods of three dimensional microfabrication have lead to the development of extremely miniaturized chemical and biotechnological systems. These so called microreactors represent novel approaches in respect of production flexibility and chemical reactions not yet applied in chemical processing. This has stimulated world-wide research in this field so that the technical feasibility of such devices has been demonstrated in the laboratory scale. 

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. 

Thus, it is more flexible to run both reactions continuously [44]. A microreactor is used for the more demanding, highly exothermic reaction, whereas a static mixer is sufficient for the second reaction. After laboratory process development, a pilot phase... 

Catalytic activity was studied in laboratory and bench-scale reactor systems. Laboratory catalytic tests (n-hexane conversion) were carried out in a through-flow reactor under the following conditions T=200-450 °C LHSV=7 h. Bench-scale tests were run in a continuous -flow high-pressure microreactor unit, using diesel oil as a feedstock. Catalysts were reduced and then sulfided at 330 °C for 5 h. The process was studied at T=300-330 °C, LHSV=3 h p=3.5 MPa and H2 CH=500 Nm /m. The criterion for catalyst activity assessment was the freezing point (-20 °C) the measurements were done for the stabilized products. 

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