Defect size analysis approach combined with silicate gel/ceramic particles for defect repair of Pd composite membranes

Pd composite membranes show great potential in several important fields, such as high-purity H2 separation and production, due to unique permeability to hydrogen and its isotopes. However, the significant defect formation on palladium membranes and following decline in H2 selectivity resulted from either preparation process or thermal/chemical stability issues exist as a great challenge for their commercial applications. The currently existing techniques for defect repair of Pd composite membranes show either high complexity or limited effect thus limiting their practical applications. In this study, we presented a novel approach, i.e., strongly adhesive and high temperature resistant silicate gel (HTRSG)/ceramic particles, in combination with home-developed “modified” liquid–liquid displacement porometry (MLLDP) for defect size distribution analysis, where the latter can provide important guidance for the selection of appropriate particles sizes. The experimental results with thin Pd membranes indicated significant improvement in H2 permselectivity without decreasing H2 permeance after defect repair treatment. Moreover, silicate gel exhibits great durability under high temperature conditions. This approach features high simplicity, effectiveness and low cost, and is especially suitable for on-site repair of spent membranes in future applications. In addition, it is universal for defect repair of other inorganic membranes, and can also be used for the sealing of membrane modules.