摘要:
用密度泛函方法和相对论有效原子实势,分别对PdCO2，PdCO和PdH的基态几何构型进行优化, 得到PdCO2分子基态为Cs构型, Pd与CO2分子在同一平面, 键长PdC为0.203 0 nm, CO为0.118 3 nm, CO′为0.121 0 nm, 键角∠OCO′为154.215°,电子状态为1A′; PdCO分子基态电子状态为1+, 键长PdC为0.183 4 nm, CO为0.114 0 nm, 键角∠PdCO为180°; PdH分子基态为2∑, 键长PdH为0.152 6 nm。根据电子-振动近似理论计算了不同温度下金属Pd 与CO2，CO及H2分子反应的生成热力学函数, 导出了反应平衡压力随温度的变化关系。分析认为杂质CO2气体引起Pd合金膜中毒可能是由于CO2分子吸附在Pd膜表面,形成Pd的CO2化合物后，再自发分解为PdO和CO，而使Pd表面出现O和CO中毒所致。
Abstract:
The structures of PdCO2, PdCO, and PdH are optimized by the relativistic effective core potential (RECP) and the density functional theory B3P86 method. The results show that the stable geometry of Pd-CO2 molecule is plane structure. The ground state of PdCO2 is (X1A′) of Cs group. The structure parameters of RPdC, RCO, RC O′ and∠OCO′ are 0.203 0 nm, 0.118 3 nm, 0.121 0 nm and 154.215°,respectively. For PdCO molecule, the ground state is 1∑+, and the structure parameters of R(PdC), R(CO), and ∠PdCO are 0.183 4 nm, 0.114 0 nm, and 180°, respectively. The ground state of PdH is 2∑, and the bond length is 0.152 6 nm. Furthermore, the thermodynamic functions of PdCO2, PdCO, and PdH are also calculated according to electronic-vibration approximation. An
点击查看大图
下载:
