Effect of different metal in situ growing routes on the morphology and gas separation properties of polyetherimide/palladium nanocomposite asymmetric membranes

•An innovative synthesis of polymer/palladium asymmetric membranes is reported.•Specific location of in situ grown Pd nanoparticles within the membranes is obtained.•Significant enhancements of H2 permeance values without detrimental effect on the selectivity are achieved.

Objective: Here we report on an innovative synthesis of polymer/palladium asymmetric membrane that allows a control of the membrane morphology, the specific location of in situ grown Pd nanoparticles within the membrane and significant enhancement of H2 permeance values with respect to the reference polymer membrane.Materials and method: Nanocomposite asymmetric films have been prepared from polyetherimide and palladium acetate for Pd amount ranging from 0 to 15 wt%. In this work, we have at first demonstrated that polyetherimide/palladium acetate membranes of different porous microstructures could be successfully prepared from a cononsolvent process. The influence of the composition of the PEI solution and of the cononsolvent immersion bath on the precursor membrane morphology was studied. Pd nanoparticles were then in situ grown within the membranes by two different post-treatments, an annealing treatment with a final step at 220 °C or a chemical treatment consisting in immersing the precursor membranes in a methanol/sodium borohydride solution.Results: In this work, we have at first demonstrated that polyetherimide/palladium acetate membranes of different porous microstructures could be successfully prepared from a cononsolvent process. The structure and the repartition of the nanoparticles, determined from XRD and TEM characterizations, were discussed as a function of the in situ generation routes. The gas permeance was determined for H2 and CO2 and the ideal H2/CO2 selectivity factor was analysed for the two nanocomposite series. The nanocomposite membrane series prepared from the annealing post-treatment exhibited particularly interesting properties towards H2 separation applications.