Overview of Pd-based membranes for producing pure hydrogen and state of art at ENEA laboratories

Membrane reactors for producing hydrogen are devices coupling a membrane and a catalyst bed: they perform simultaneously both the reaction and the hydrogen separation. In this way, reaction conversions beyond the thermodynamic values can be attained (shift effect). In particular, Pd-based dense membranes are capable to separate selectively the hydrogen from other gases. Their use into membrane reactors which carry out dehydrogenation reactions permits producing ultra-pure hydrogen. This review considers the techniques of manufacturing Pd-based membranes, the design of membrane reactor modules and the processes for producing pure hydrogen via reforming of hydrocarbons and alcohols. Mainly, the work carried out at ENEA Frascati laboratories and a comparative description of other relevant technologies are considered in this paper.