Adsorption Behavior Of Impurity Gas On Pd Alloy Surface

Based on the relativistic effective core potential (RECP/SDD) for Pd and Y atoms, AUG-cc-pVTZ or 6-311++G** basis function for N atom and 6-311++G** basis function for C and O atoms, the structures of PdN, PdN₂, PdH₂, Pd-CO, Pd-OC, YCO and YN₂ have been calculated using B3LYP method in Gaussian 98 program, and the thermodynamic functions have been calculated by ah initio method.The results show that the ground state of PdN is ⁴E^- and the ground state of PdN₂ is C_∞V symmetry and ^-Σ⁺ state. The Murrell-Sorbie potential energy function of PdN molecule has been fitted through the least square fitting, and the potential energy function of PdN₂ is given by many-body expansion theory. The potential energy curves describe the structure character of PdN and PdN₂ ground state molecules rightly, which detail the inner transfer process of Pd.Considering the characteristics of different motion types, the vibration energy or electronic and vibration entropy of the molecule is assumed to be the corresponding value of its solid state. ΔH^?, ΔS^?,ΔG^? and reaction equilibrium pressures of Pd or Y with N₂, H₂ and CO have been calculated based on this approximation. Comparing the equilibrium pressures, the capability of N₂, H₂ and CO adsorbed on Pd surface can be gained, and a project can be brought to reduce adsorption of CO on Pd surface. Comparing ΔG^? of YCO(s), YN₂(s), YH₂(s), Pd-CO(s), PdN₂(s) and PdH₂(s), the capability of Y adsorbing CO, N₂ and H₂ can be gained, as well as the capability of Y and Pd adsorbing CO, N₂ and H₂. Then it can be gained that when Y is mixed in Pd, it can weaken the adsorption of CO and N₂ on Pd-Y alloys surface as well as strengthen the adsorption for H₂ on alloys surface.