NO_x分子在[Ag]-AlMOR分子筛中的吸附

NO_x Adsorption in [Ag]-AlMOR Molecular Sieve

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.

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 Drool^3 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 η^1-N mode was more stable than η^1-O mode. In the η^1-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.