Chapter 13: Palladium-based Selective Membranes for Hydrogen Production

In a membrane reactor one or more chemical reactions, generally catalytically promoted, are carried out in the presence of a membrane selectively permeated by one of the reaction products. As result of a lower reaction temperature, another major advantage emerges, i.e. the possibility of a better heat integration, as the use of gas exhausts from a gas turbine or solar heated molten salts. In view of the significant potential advantages, attention hereafter is paid mostly to membrane reactor engineering focusing on the most interesting applications.

Membrane integration criticism has to be carefully faced. If the selective membrane is directly integrated in the reaction environment, coupling catalyst and membrane operating conditions leads to the necessity to define a compromise optimization in order to promote both the kinetics and permeability, without damaging the membrane always requesting stringent thermal threshold. On the other hand, the membrane can be integrated externally, by an architecture which foresees reaction and separation steps in series. In this way, catalyst and membrane operating conditions are independent and their optimal operating conditions can be defined separately.

It is a worthy assessment that the development of such innovative reactors requires ad hoc design criteria definition.

Such a note, focused mainly on hydrogen production processes, is articulate in:

• Basic features of membrane reactors

• Open or closed architecture

• Heat integration strategies

• Case studies applications.