Plate-Type Membrane Microreactors

Currently, the membranes incorporated in MMRs are mainly zeolite and Pd-based dense metal ones. Incorporation of these membranes in microreactors can be achieved using one of the preparation methods described in previous chapters. 

An important issue in catalytic MMRs is the proper incorporation of active catalysts within microchannels. Packing a powdered catalyst in the microchannels presents obvious difficulties in terms of pressure drop and flow distribution. Therefore, the catalyst is usually deposited as a thin catalytic coating on the surface of the microchannels in MMRs. These coatings should not only provide enough catalytic loads, but also have high mechanical stability to withstand extremely severe conditions in terms of temperature and 

Synthesis of the oxide powder slurry. The oxide power is dispersed under vigorous stirring in deionized water with acetic acid and acrylic acid as binders. The suspension is kept under stirring for 24 h prior to deposition at room temperature. 

Coating deposition. The slurry is applied to the microchannels of the platelets using a syringe. Even though the use of a syringe is not a commercially viable process in the production of bulk quantity of coated platelets, it is a convenient way to achieve catalyst deposition on a laboratory scale with good layer quality. Any excess of suspension should be wiped off. 

Drying and calcination at elevated temperature. The platelets are dried at ambient temperature in air. The coated microchannel platelets are finally calcined at 800°C for 4h. 

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T. Eukuda, T. Maid, K. Mae, Design of a plate-type catalytic microreactor with CO2 permeation membrane for water-gas shift reaction, Chem. Eng. Technol. 35 (2012) 1205-1213. 

A distinctive feature of microreactors is the microchannels for fluid flow. MMRs are mainly characteristic of such microchannels with anchored catalysts for reactions and miniature membranes to perform separation, which are formed on the porous ceramic or metal supports. Based on the configuration and architecture of the reactor, MMRs can be classified into two categories plate type and tubular type. 

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