Example 1 Product Removal with Membranes Extractor

Example 1 Product Removal with Membranes ( Extractor ) 

Removal of the products of reversible reactions was the area where, initially, the most intensive efforts related to the development of membrane reactors were undertaken. The simple principle, which is based on removing one of the products of a desired reaction via a membrane from the reaction zone is illustrated in Fig. 12.5. 

In most of the studies mentioned, it was possible to demonstrate positive effects related to the presence of the membrane. Results of reactor simulations were 

1 to 12.5.6. Subsequently, a reactant distributor was considered which aimed to enhance selectivity with respect to an intermediate product. The corresponding results are presented in Section 12.6. In both cases the reaction rates of the model reactions investigated were measured carefully for the specific catalysts applied. This information was then used to describe and analyze the two membrane reactor concepts investigated. 

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Improved selectivity in the liquid-phase oligomerization of i-butene by extraction of a primary product (i-octene C8) in a zeolite membrane reactor (acid resin catalyst bed located on the membrane tube side) with respect to a conventional fixed-bed reactor has been reported [35]. The MFI (silicalite) membrane selectively removes the C8 product from the reaction environment, thus reducing the formation of other unwanted byproducts. Another interesting example is the isobutane (iC4) dehydrogenation carried out in an extractor-type zeolite CMR (including a Pt-based fixed-bed catalyst) in which the removal of the hydrogen allows the equilibrium limitations to be overcome [36],... 

Pervaporation-assisted catalysis is a typical example of an operation eflide-ntly carried out in extractor-type catalytic membrane reactors. Esterification is by far the most studied reaction combined with pervaporation. " Esters are a class of compounds with wide industrial appUcation, from polymers to fragrance and flavour industries. Esterification, a reaction between a carboxylic acid and an alcohol with water as a by-product, is an equilibrium-limited reaction. So, this is a typical reaction that can be carried out advantageously in a extractor-type membrane reactor. By selectively removing the reaction product water, it is possible to achieve a conversion enhancement over the thermodynamic equilibrium value based on the feed conditions. 

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