Methane Steam Reforming in a Staged Membrane Reactor: Influence of the Number of Stages and Amount of Catalyst

In this work, the performances of a tube-shell staged membrane reactor (SMR) for methane steam reforming are analyzed by computer modelling in terms of methane conversion, hydrogen recovery factor and hydrogen recovery yield. The internal tube (the permeate side) is represented by the Pd-alloy membrane, whereas the reaction occurs in the packed bed retentate side. The staged membrane reactor is composed of several reactive and inert stages laid out in alternative series and tilled with catalytic and inert pellets, respectively. For this analysis, a I-D model including momentum, energy and mass transfer is used. Its validation was already performed by means of experimental data taken from literature (Caravella et al., 2008). In particular, the specific topic of the investigation is the role of the number of reactive and inert stages and of the amount of catalyst, comparing the obtained results with those of the conventional membrane reactor (MR). A very significant result of the analysis is that an SMR with a sufficiently high number of stages can reach performances very close to those of the MR with a significantly smaller amount of catalyst (up to 70% lower) for all the temperatures considered. As a consequence, the amount of saved catalyst can be evaluated, relating it to the performance losses with respect to the conventional MR and providing a qualitative and quantitative rule to exploit efficiently the catalyst.