Fabrication of Ni-alumina Composite Membrane via Powder and Bulk Impregnation Method for Hydrogen Separation

This work reports two preparation methods of Ni-Al2O3 composite to be used as a hydrogen separation membrane. The first method was powder impregnation while the second method was soaking-drying-firing or bulk impregnation. In the first method, the 10 wt pct Nickel (II) nitrate hexahydrate solution was mixed with Al2O3 powder. The mixed powders were dried at 100°C and uniaxially pressed into a disk shape at 7 MPa. The densification of composite membranes was accomplished by pressureless sintered at 900–1300°C. For the second preparation method, the Al2O3 disk support was prepared firstly by uniaxially pressing Al2O3 powder at 7 MPa and then sintered at 1000–1200°C for 2 h. After that, the Al2O3 support was soaked into 10 wt pct Ni solution, dried at 100°C and calcined at 900°C for 2 h. The soaking-drying-firing sequence was repeated ten times to finally obtain the Ni-Al2O3 membranes. After preparation process, the membranes fabricated from these two methods were reduced at 910°C for 2 h in hydrogen atmosphere. The effect of the preparation method on properties of membranes in terms of density, porosity, phase and microstructure are discussed.