Performance of a Pd/PSS membrane reactor to produce high purity hydrogen via WGS reaction

In this work, the performances of WGS reaction carried out in a porous stainless steel (PSS) supported Pd-based membrane reactor (MR) have been experimentally investigated in terms of conversion, hydrogen recovery and hydrogen purity of permeate stream. A 20 μm thick Pd-based membrane prepared by electroless plating and a high temperature Fe–Cr based WGS catalyst have been used during the experimental campaign. Influence of parameters such as reaction pressure (from 7 to 11 bar) and gas hourly space velocity, GHSV (from 3450 to 14,000 h−1), at different steam to carbon ratio (from 1/1 to 4/1) has been investigated at the reaction temperature of 390 °C. As a best result of this work, by supplying a hydrogen rich-gas mixture such as 8% CO, 32% H2O, 24% CO2, 36% H2 to the MR operated at GHSV = 3450 h−1 and reaction pressure of 11 bar, almost 80% CO conversion, 70% hydrogen recovery with hydrogen permeate purity around 97% have been reached. Membrane fouling due to coke coverage on the membrane surface has been proven to be fully reversible: after 700 h of tests in WGS mixtures, H2 permeation and both H2/He and H2/N2 ideal selectivities remained unchanged.