【摘要】 采用Dmol3程序中密度泛函理论(DFT)的广义梯度方法GGA/BLYP和DND基组研究了银离子交换的丝光沸石([Ag]-AlMOR)结构及其对NOx分子吸附性能的影响,获得吸附复合物的平衡几何结构参数、吸附能以及红外振动频率等数据.结果表明,NOx分子与丝光沸石间的主要作用力为NOx分子中的氮(或氧)原子上的孤对电子和Ag+间的静电作用力.吸附能数据表明,NOx分子以η1-N模式吸附在[Ag]-AlMOR分子筛中的结构更稳定;在η1-N模式中,NOx分子吸附作用强度的次序为NO>NO2>N2O.红外振动频率结果表明,吸附态NOx分子中N—O和N—N键伸缩振动频率的位移趋势与N—O和N—N键变化规律基本相一致.另外,对[Ag]-AlMOR分子筛的抗硫、抗水及抗氧化性能也进行了研究和分析.更多还原

【Abstract】 NOx adsorption in [Ag]-AlMOR molecular sieve was investigated by using density functional theory (DFT) with the generalized gradient approximation (GGA) method and the Becke exchange plus Lee-Yang-Parr correlation (BLYP)level as well as the DND basis set of the Dmol3 module. Equilibrium structure parameters, adsorption energies, and vibrational frequencies were obtained and compared. Results showed that the interaction between NOx and [Ag]-AlMOR was dominated by the action between the lone electron pair of N or O of NOx and Ag+. Calculated adsorption energies indicated that η1-N mode was more stable than η1-O mode. In the η1-N mode, adsorption energy values of NOx in [Ag]-AlMOR followed the order: NO>NO2>N2O. The trend of N—O and N—N bond vibrational frequencies in [Ag]-AlMOR complexes compared to free NOx were in line with the changes of N—O and N—N bond distances. The resistance of [Ag]-AlMOR to SO2, H2O, and O2 was also studied and analyzed.更多还原