Reactive Distillation

Also known as catalytical distillation, this technique involves the use of a catalyst within a distillation column (see Figure 3.8.16). When the reaction and distillation occur in one step, a separate reaction step is eliminated.

The chemical reactions best suited for reactive distillation are those characterized by unfavorable reaction equilibria, high reaction heat, and significant reaction rates at distillation temperatures. For example, reactions with unfavorable equilibria are those in which the reaction products contain high concentrations of unconverted reactants. For these reactions, continuously removing one or more products from the reacting mixture substantially increases product conversion. A recently introduced structured packing that incorporates a catalyst may have significant benefits with this application.

A commercial process that uses catalytic distillation is the production of methyl-ieri-butyl ether (MTBE), an octane enhancer made from methanol and isobytlene. Other

Phase III

Phase I

Permeation applications under testing include cumene from benzene and propylene; tert-amyl methyl ether (TAME); and ETBE, an octane enhancer similar to MTBE, made by reactive distillation from C4 and C5 feedstocks.

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