BASIC CONCEPT AND ADVANTAGES

In many conventional reactors, the reactants arc typically premixed and the products are brought in contact with the reactants until equilibrium is approached. Thus the reaction conversion is limited by the reaction equilibrium. Furthermore, uncontrolled contact between the reaction components may lead to certain reaction paths for some undesirable intermediate or side products. Finally, the valuable catalysts need to be immobilized or encapsulated in some carriers and their loss should be minimized to make the catalytic reaction processes economically viable. 

Introduction of a permselective membrane to a reactor zone opens up opportunities for resolving the above important reaction performance issues. An overview of this concept will be given next followed by some examples portraying the benefits of a membrane reactor. 

It is instructive to illustrate one of the major advantages of a membrane reactor by examining a generic reversible reaction  

The implications of being able to increase the conversion of an equilibrium reaction by using a permselective membrane are several. First, a given reaction conversion may be attained at a lower operating temperature or with a lower mean residence time in a membrane reactor. This could also prolong the service life of the reactor system materials or catalysts. Second, a thermodynamically unfavorable reaction could be driven closer to completion. Thus, the consumption of the feedstock can be reduced. A further potential advantage is that, by being able to conduct the reaction at a lower temperature due to the use of a membrane reactor system, some temperature-sensitive catalysts may find new applications [Matsuda et al., 1993]. 

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