Palladium (Pd) nanoparticles offer excellent hydrogen affinity in mixed matrix membrane for gas separation. In order to avoid aggregation, Pd nanoparticles have to be stabilized before blending into polymer matrix. Pd nanoparticles can be thermodynamically stabilized and dispersed using electrostatic and/ or steric forces of a stabilizer which is typically introduced during the formation of Pd nanoparticles in the inversed microemulsion. Polyvinylpyrrolidone, polyethylene glycol (PEG) and sodium hydroxide in ethylene glycol exhibited good effect on particles passivation. However, the effects of these stabilizers on membrane morphology and separation performance were unknown. The aim of this work is to incorporate polymer-stabilized Pd nanoparticles into Polysulfone (PSf) membranes for hydrogen separation. The microstructure of Pd nanoparticles was first analyzed by TEM. Phase inversion method was then adopted for the preparation of asymmetric PSf/nanoPd MMMs. The separation performance of MMMs was investigated by using nitrogen and hydrogen as test gases and the membrane characteristics were further studied using SEM and FTIR. The highest permeability for H2 was 255.82 GPU with selectivity of 6.89. The results suggested that PEG provides good contact between nanoparticles and the polymer. TEM and FTIR results revealed that these stabilizers have significant effects on the synthesized Pd nanoparticles size. Also, SEM results showed that the MMMs incorporated with thermodynamically nanoPd in PEG achieved satisfactory asymmetric structure which explains the good performance in gas separation.
Microporous materials with tailored structural properties for enhanced gas separation