Repair of Pd-based composite membrane by polishing treatment

In this study, polishing treatment was introduced to repair Pd-based composite membrane. Some pinholes remained after sputtering with palladium followed by heat-treatment at 723 K for 2 h. The pinholes drastically decreased the hydrogen perm-selectivity of the Pd-based composite membrane. In order to remove the pinholes, we introduced polishing treatment after the palladium sputtering. Scanning election microscopy (SEM) analysis and helium leak tests confirmed the effectiveness of the polishing treatment in removing the pinholes. The helium leaks were drastically decreased by the polishing treatment. Hydrogen permeation and helium leak tests showed that the polishing treatment increased the hydrogen perm-selectivity from 52 to >40,000 with a hydrogen permeation flux of 1.8 × 10−1 mol m−2 s−1 at a pressure difference of 100 kPa and temperature of 673 K.The advantage of our membrane fabrication procedures lies in its simplicity. Our coating and polishing method offers the promise of highly reproducible Pd-based composite membrane.

► Pd-based composite membrane could be repaired with very simple polishing treatment.
► The H2/He perm-selectivity increased from 52 to >40,000 after polishing treatment.
► The polishing treatment provides high reproducibility of Pd-based composite membrane.