Palladium alloy tube application and separation of impurities. Palladium alloy hydrogen purification principle is, under the 300-500 ℃, the stay on one side of the purification of hydrogen in palladium tube, adsorb hydrogen on the palladium tube wall, as a result of the palladium 4 d shell lack of two electrons, it can generate unstable with hydrogen bonds (palladium and the reaction is reversible hydrogen), under the action of palladium, ionized hydrogen protons as the radius of 1.5 x 1015 m, while palladium lattice constant of 3.88 x 10-10 m (20 ℃), it can through palladium tube, under the action of palladium protons combined with electrons to form hydrogen molecules, escape from the other side of the palladium tube. On the surface of palladium tube, the undissociated gas is not permeable, so high purity hydrogen can be obtained from palladium tube. Although palladium has unique transmittance to hydrogen, it is difficult to use pure palladium as transmittance membrane because it is easy to oxidize at high temperature and low recrystallization temperature. By adding a palladium IB and Ⅷ element, made from alloy, palladium can improve mechanical properties of palladium. At present, silver accounts for about 20-30% of palladium alloys, and the content of other components (such as gold, etc.) in steel pipes is less than 5%. The rate of hydrogen penetration through palladium alloy is related to temperature, film thickness, and pressure difference between raw hydrogen and pure hydrogen (delta P). Increasing temperature, increasing delta P and decreasing film thickness will increase hydrogen penetration rate. However, when the temperature increases, the tensile strength of the permeable membrane decreases. Therefore, the temperature of palladium alloy tube is usually controlled at 450℃. Certain impurities can lead to palladium poisoning, deterioration of permeability and even destruction of membrane. Palladium poisoning is caused by arsenide, halogen, oil vapor, sulfur and dust. Palladium alloys can be made into tubes (called palladium tubes) or membranes (called palladium membranes).
Tag: Palladium alloy tube ， Palladium alloy
