Micro-packed Bed Reactors

Micro packed bed reactors have a larger flow-through channel, which contains particles brought to contact [65,68,69]. The flow of the gas-liquid mixture goes through the interstices and in this way a dispersive action is given, that is, continuously renewing the interfaces. 

The most striking advantage of the concept is the resemblance of industrially applied principles for gas-liquid and gas-liquid-solid operation. Commercial particles may be employed and exchange is fast and flexible. As further advantage, relatively large flows are provided, even when operating with a single device. Even parallel operation of many devices has been demonstrated [69]. 

Flow-pattern characterization is more difficult as the particle bed is not transparent and covers most of the flow-through chamber. Owing to the size distribution of the particles and respectively the width distribution of the interstices one major advantage of microreactors, that is, the structural and flow regularity, is decreased in impact, albeit not lost. Here, the availability of regular particles with uniform size can change the situation. 

Two-phase pressure drop in micropacked beds is very large, particularly, for particles with small diameter, and is significantly influenced by capillary forces, especially at higher reactor-to-partide diameter ratios [94]. The two-phase flow in micro packed bed reactors with radially nonuniform porosity distribution was simulated by solving a two-dimensional hydrodynamic model based on the volume-averaged mass and momentum conservation equations. 

A cartridge heater is inserted in the cover plate of the packed bed reactor [68]. The base plate provides conduits to the microreactor. The outlets are standard high-pressure fittings. Thermocouples are inserted in the slurry feed channels. 

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K. F., A micro packed-bed reactor for chemical synthesis, in Ehrfeld, W. (Ed.), Microreaction Technology 3rd International Conference on Microreaction Technology, Proc. of IMRET 3,... 

These characteristics make the cross-flow microreactor a useful experimental tool for investigating kinetics and optimizing reaction conditions. Experiments regarding CO oxidation confirmed the ability of the micro-packed bed reactor to deliver valuable information about kinetics and mechanism, which compares well with data previously obtained in macroscale reactors. 

Jensen, K. F., A micro packed-bed reactor for chemical synthesis, in Ehrfeld, W. 

The randomly micro packed bed reactors are used mainly for catalyst screening [3, 4]. The advantage of this type of catalytic reactor stems from the fact that the developed catalyst used in traditional reactors can be applied. In addition, the use of fine particles greatly increases the mass transfer between the fluid bulk and the catalyst surface. 

Estimate the pressure drop in a metallic foam with a porosity of efoam = 0.9 and a SSA of = 5000 m m and compare the result with pressure drop in a microstructered reactor with square channels and a micro packed bed reactor with a porosity of = 0.4. The three devices should have the same surface area referred to the volume occupied by the fluid, commonly called void volume Solution ... 

Figure 6.11 Mass transfer in micro packed bed reactors as function of superfidal velocity with the particle size as parameter. (Sc= 1 [, =0.5 < = 18-10" Pas /r = 1.2kgm ).

X.K., Myrstad, R., Venvik, H.J., Pfeifer, P., and Holmen, A. (2011) Characteristics of 16. an integrated micro packed bed reactor-heat exchanger for methanol synthesis... 

Tidona, B., Desportes, S., Altheimer, M., Ninck, K., Von Rohr, P. R. (2012). Liquid-to-particle mass transfer in a micro packed bed reactor. International Journal of Heat and Mass Transfer, 55(4), 522-530. 

Characteristics of an Integrated Micro Packed Bed Reactor-Heat Exchanger for methanol synthesis from syngas. Chemical Engineering Journal, Vol. 167, 496-503. 

Hayer F, Bakhtiary-Davijany H, Myrstad R, Holmen A, Pfeifer P, Venvik HJ. Characteristics of integrated micro packed bed reactor-heat exchanger configurations in the direct synthesis of dimethyl ether. Chemical Engineering and Processing 2013 70 77-85. 

Hydrogenation of cydohexene Micro-packed-bed reactor and microchannel with staggered array columns [73,76]... 

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