Microstructured falling film reactor

Yeong, K. K., Gavriilidis, A., Zape, R., Hessel, V., Catalyst preparation and deactivation issues for nitrobenzene hydrogenation in a microstructured falling film reactor, Catal. Today 81, 4 (2003) 641-651. 

FIGURE 11 Components (left) and schematic drawing (right) of the microstructured falling film reactor (64 parallel channels, 300 pm wide, 100 pm deep, 78 pm long) [100], (Adapted with permission from Elsevier.)... 

K.K. Yeong, A. Gavriilidis, R. Zapf, V. Hessel, Experimental studies of nitrobenzene hydrogenation in a microstructured falling film reactor, Chem. Eng. Sci. 59 (2004) 3491. 

Microstructured devices for fluid-fluid systems exist in a number of configurations. They can be roughly classified into three types based on the contacting principles [ 1] micromixer, microchannels, and falling film microreactors. The first two types of devices are used for all fluid-fluid applications while the microstructured falling film reactor is used only for gas-liquid systems. Depending on the application, these microstructured devices can also be used in series, for example. 

Microstructured Falling Film Reactor for Gas-Liquid Reactions... 

The main drawback of the microstructured falling film reactor is the short residence time of the liquid in the channels, which typically varies between 5 and 20 s, depending on physical properties of the liquid and the operating conditions. The residence time can be increased by lengthening the microchannel or by decreasing the angle of descent, which can be achieved by helicoidal microchannel falling... 

Mass Transfer in Microstructured Falling Film Reactors... 

Example 7.4 investigates the mass transfer in microstructured falling film reactor. 

In a vertically placed 20 parallel channel microstructured falling film reactor of 60 mm length, 1 mm width, and 0.3 mm depth, gas and liquid flows with 46 ml min and 3.6 ml min , respectively, estimate (1) thickness ofthe wall film, (2) mean velocity of liquid film, (3) Fourier number, (4) Reynolds number, and (5) mass transfer coefficient, k. ... 

Microstructured falling film and micro bubble column reactor Single micro channel operating in annular flow regime Microstructured falling film reactor Microstructured falling film reactor... 

The microstructured falling film reactor has also been used for chlorination reactions [77]. Chlorination of acetic acid at a temperature over 140 C was carried out and the by-product (dichloroacetic acid) was reduced significantly, meaning that there is no need for additional costly and time-consuming separation processes. Further, a photochemical gas-liquid reaction by the selective photochlorination of toluene-2,4-diisocyanate (TDl) was demonstrated [78]. 

If we consider a microstructured falling film reactor, the liquid phase is reduced to a small liquid layer between the gas phase and the solid catalyst as shown schematically in Figure 8.6a. The thickness of this film (5(j ,) depends on the liquid flow as discussed in Chapter 7. Because of the surface forces the wetting liquids form a meniscus within the chaimel. With increasing flow rate the meniscus becomes more and more flat. This is demonstrated on Figure 8.6b for a channel with a width of 300 pm and a height of the side walls of 100 pm [11]. The channel... 

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