Computer Simulation Of Hydrogen Permeation In Pure Pd And PdAu Alloy

Hydrogen, as a clean energy carrier, has potential applications due to its goodcombustibility, fast rate of combustion, pollution-free combustion, cleanliness, etc.Hydrogen will become a regenerated resource if the industrialization of solarhydrogen production comes true. Owing to their perfect hydrogen permeability,Palladium (Pd) and its alloy membranes are applied for hydrogen separation andpurification. The performance prediction of Pd-based membranes under differentconditions is important for the practical production. Based on the reliable theory andfeasible method, we can predict the performance of Pd membranes by modeling toreduce the workload of experimental studies.The performance prediction of Pd-based membranes by modeling can be dividedinto two aspects. One is related to the hydrogen diffusion in the bulk of the membrane,and the other is related to the adsorption of hydrogen on the surface of the membrane.In this dissertation, many methods are applied to study the diffusion of hydrogen,including the studying of binding energy of hydrogen to metal lattice applyingCASTEP module which is based on the density functional theory (DFT), and thecalculation of diffusion coefficients of hydrogen in Pd applying Discover modulewhich is based on molecular dynamics. The Binding energy of the Octahedral-site (Osite) in pure palladium is -0.10eV which is obtained from CASTEP module. Thisvalue is close to the referenced one (-0.12 eV) which is obtained from VASP module.As for the Tetrahedron-site (T site), we find out that the hydrogen atom mustovercome an energy barrier of 0.33 eV if it shifts from O site to T site. This resultindicates that the hydrogen atom actually locates at O site only, which is inaccordance with the reported reference. Additionally, we carried out the calculation ofthe binding energy of Pd-Au alloy. We find out that when Au content is beyond 25 %in Pd, the solubilityof hydrogen decreases as theAu content increases.