Effect of CeO2-YSZ intermediate layers for enhanced hydrogen permeance of palladium membrane supported on porous α-Al2O3 tube
摘要
Hydrogen is considered a future fuel. However, mostly hydrogen is generated with other gases such as CO, CO2, N2, etc. Therefore, the separation of hydrogen from these gases is vital. Palladium-based membranes are commonly used for hydrogen separation. However, preparing a defect-free membrane on porous substrate is still a major challenge. This study highlights the development of appropriate intermediary layers to facilitate uniform palladium deposition on commercially available alumina substrates. CeO2-YSZ intermediate layers are used on a porous alumina tube before depositing the palladium layer. YSZ and CeO2 layers are deposited through the vacuum-assisted dip-coating method, and the palladium layer is deposited on the intermediate CeO2-YSZ layers using the electroless pore plating (ELP-PP) method. The single solution of the Pd is used to prepare the membrane by optimizing the solution's N2H4 (0.1 M–0.5 M) concentration. SEM and EDS analyses are carried out to investigate the membrane surface morphology and pore size distribution, focusing on understanding the intermediate layer's effect. The permeation property of the membrane is tested at different temperatures (300–400 ℃) and pressure ranges (0.5–3.0 bar). The membrane testing is performed with pure hydrogen and hydrogen and nitrogen mixture of different compositions. At 400 °C, the membrane permeability was 3.3 × 10–6 mol s−1 m−2 Pa−1 at 1 bar, which is one of the highest reported values compared with the literature. The nitrogen is retained completely, ensuring the hydrogen's high purity.