Enhancing the production of hydrogen via water–gas shift reaction using Pd-based membrane reactors

In this work, it is described an experimental study regarding the performance of a Pd–Ag membrane reactor recently proposed and suitable for the production of ultra-pure hydrogen. A dense metallic permeator tube was assembled by an innovative annealing and diffusion welding technique from a commercial flat sheet membrane of Pd–Ag. A “finger-like” configuration of the self-supported membrane has been designed and used as a packed-bed membrane reactor (MR) for producing ultra-pure hydrogen via water–gas shift reaction (WGS). ZnO/Al2O3 catalyst, from REB Research & Consulting, was used for packing the WGS membrane reactor. The performance of the reactor was evaluated in terms of CO conversion and H2 recovery in a wide range of conditions: temperature from 200 °C to 300 °C, feed pressure from 1.0 bar to 4.0 bar, vacuum and sweep-gas modes and with a simulated reformate feed (4.70% CO, 34.78% H2O, 28.70% H2, 10.16% CO2 balanced in N2). Also, the effect of the reactants feed composition was investigated and discussed. CO conversions remained in most conditions above the thermodynamic equilibrium based on feed conditions. In particular, it is worth mentioning that around 100% of CO conversion and almost complete H2 recovery was achieved when operating the MR at 300 °C with a GSHV = 1200 LN kgcat−1 h−1, Pfeed = 4 bar, Pperm = 3 bar and using 1000 mLN min−1 of sweep-gas.