Toward extensive application of Pd/ceramic membranes for hydrogen separation: A case study on membrane recycling and reuse in the fabrication of new membranes

• The palladium at Pd/Al2O3 membranes can be recycled by HCl–H2O2 treatment.
• Both the recycled palladium and Al2O3 substrate can be reused.
• The prepared new membranes are as permeable and selective as the originals.
• It reduces the membrane cost and solves the problem of limited membrane life.

The increasing applications of hydrogen energy greatly promote the development of composite palladium membranes, which are ideal for hydrogen purification because of their high permeability, excellent permselectivity and easy modulation. However, these membranes are still associated with problems such as high cost and limited operating life. This work investigates membrane recycling and reuse as a solution to these problems. Pd/Al2O3 membranes were prepared by electroless plating. The recycling of palladium was achieved by treating it with HNO3 and HCl–H2O2 agents. Adequate results were achieved using an agent composed of 2 mol/L HCl and 1 mol/L H2O2. The recycled palladium can be utilized in a new plating bath, while the Al2O3 substrate remaining after palladium recycling can be reused as the substrate material for the preparation of new membranes. The surface morphology, thickness and permeation performances of the recycled membranes, as characterized by scanning electron microscopy, metallographic microscopy and permeation tests, are similar to those of the original palladium membranes. It can be concluded that the recycling and reuse of the Pd/Al2O3 membranes are successful and may provide a solution to the current key problems associated with the application of composite palladium membranes.