Stability of electroless pore-plated Pd-membranes in acetic acid steam membrane-reformers for ultra-pure hydrogen production

Abstract

Electroless Pore-Plated (ELP-PP) membranes were successfully incorporated for the first time into a membrane reactor to produce hydrogen by acetic acid steam reforming (AASR), exhibiting adequate resistance against harsh operating conditions. Membranes were prepared onto tubular PSS supports modified with Pd/CeO2 particles and scaled-up around four times in length with high reproducibility respect previous studies. H-2 permeances from 4.49 to 5.67.10(-4) mol m(-2) s(-1) Pa-0.5 were found for pure H-2 at 350-450 degrees C, decreasing for mixtures due to concentration-polarization at higher pressures but also certain inhibition caused by CO2 at pressures below 50 Pa-0.5. The combination of membranes with Ni/SBA-15 catalysts in packed-bed membrane reactors (PBMR) evidenced the simultaneous improvement of acetic acid conversion and hydrogen yield respect to analogous experiments in traditional packed-bed reactors (PBR). A very similar product distribution was obtained for both configurations, PBR and PBMR, when using fresh catalysts, although marked deviations were found in case of regenerating the catalysts. Then, higher selectivity towards coke reached for PBMR, which lead to around 30% for the most elevated pressure under investigation. However, even at these harsh conditions, the mechanical integrity of ELP-PP membranes was maintained. Thus, the benefits of combining catalysts and ELP-PP membranes in a PBMR for AASR were demonstrated.