Modelling and optimization of hydrogen yield in membrane steam reforming reactors

Low-temperature steam reforming is an interesting alternative to traditional hydrogen production methods, making it possible to couple the reactor with solar heating. The main limitation in this process is imposed by thermodynamic equilibrium, which may be overcome by considering the use of a pre-reformer, in which equilibrium conversions are easily reached, followed by a membrane reactor, in which additional hydrogen production takes place along with its separation from the other products. This work is based on an overview of studies previously carried out by the same authors on the influence of pressure on the interplay between transport, permeation, and reaction in methane steam reforming membrane reactors and focuses on the behaviour of yield, defined as the ratio between the flow rate of hydrogen permeating across the membrane and at the inlet of the reactor. In the present work we show that all the curves depicting the yield, corresponding to a variety of operating conditions, can be rescaled onto a single master curve, thus providing the most compact representation of the reactor's performance. Furthermore, we show that the invariant scaling is robust with respect to changes of the reactor geometry.