Membrane microreactors concept

Following the principles of process intensification, there has been recently a growing interest in integration of unit operations by merging a microreactor vrith a membrane separation unit. The concept of membrane microreactors is applied in biocatalysis [97,98], and chemical catalysis where various catalysts can be attached to the membrane pores (zeolites [99], carbon nanofibers as support [100], metals [101]) (Figure 9.25). 

A further improvement of the multiphase reactor concept using lipase for enantioselective transformation has been recently reported, that is, an emulsion enzyme membrane reactor. Here, the organic/water interface within the pores at the enzyme level is achieved by stable oil-in-water emulsion, prepared by membrane emulsification. In this way, each pore forms a microreactor containing immobilized... 

The concept of process intensification aims to achieve enhancement in transport rates by orders of magnitude to develop multifunctional modules with a view to provide manufacturing flexibility in process plants. In recent years, advancement in the field of reactor technology has seen the development of catalytic plate reactors, oscillatory baffled reactors, microreactors, membrane reactors, and trickle-bed reactors. One such reactor that is truly multifunctional in characteristics is the spinning disk reactor (SDR). This reactor has the potential to provide reactions, separations, and good heat transfer characteristics. 

Notably, a key problem with the use of microreactors is that, historically, many reactions have been developed to be driven to complehon by relying on the formation of either small molecules or precipitates if small molecules are one of the reachon products, they would be boiled off to drive the reaction. Both mechanisms can be a problem in microreactors. Consequenhy, work is underway to couple membranes and other separahon concepts to enable the small molecules to be extracted from the reaction mix and drive the reachon. With solids formation, the requirement is that the solids exit the system without plugging. While this has been demonstrated it is not clear whether solids formahon will be a major problem when dealing with these types of reachons. 

Demonstrate high performance desulfurizer, catalyst, microreactor and microcombustor/ microvaporizer concepts that will enable production of compact fuel processors for proton exchange membrane (PEM) fuel cells ... 

Future Trends in Reactor Technology The technical reactors introduced here so far are those used today in common industrial processes. Of course, research and development activities in past decades have led to new reactor concepts that may have advantages with respect to process intensification, higher selectivities, and safety and environmental aspects. Such novel developments in catalytic reactor technology are, for example, monolithic reactors for multiphase reactions, microreactors to improve mass and heat transfer, membrane reactors to overcome thermodynamic and kinetic constraints, or multifunctional reactors combining a chemical reaction with heat transfer or with the separation in one instead of two units. It is beyond the scope of this textbook to cover all the details of these new fascinating reactor concepts, but for those who are interested in a brief outline we summarize important aspects in Section 4.10.8. 

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