NO_x分子在[Ag]-MAPO-5(M=Si,Ti)分子筛中的吸附

NOx Molecule Adsorption in [Ag]-MAPO-5(M=Si,Ti) Molecular Sieves

采用密度泛函理论(DFT)研究了银离子交换的硅磷酸铝([Ag]-SAPO-5)和钛磷酸铝([Ag]-TAPO-5)分子筛结构及其对NOx分子的吸附,获得吸附复合物的平衡几何结构参数和吸附能.结果表明,NOx分子以η1-N模式吸附在[Ag]-SAPO-5和[Ag]-TAPO-5分子筛中的结构更稳定,其吸附作用强度的次序为NO2>NO>N2O.[Ag]-SAPO-5和[Ag]-TAPO-5对NO和NO2分子的活化程度要比N2O大.相比[Ag]-AlMOR,[Ag]-SAPO-5和[Ag]-TAPO-5对NOx分子的活化程度较大.还对[Ag]-SAPO-5和[Ag]-TAPO-5分子筛的抗硫、抗水及抗氧化性能进行了研究和分析.另外,通过自然键轨道(NBO)计算,分析了NOx分子与平衡离子Ag+之间的作用机理.

NOx adsorption in silver-exchanged aluminophosphate molecular sieves（[Ag]-SAPO-5 and [Ag]-TAPO-5） was investigated using the density functional theory（DFT）.Equilibrium structure parameters and adsorption energies were obtained and compared.The results indicated that the η1-N mode was more stable than the η1-O mode.The adsorption energy values of NOx followed the order： NO2NON2O.Compared to the free gas state,the bond parameters of NO and NO2 in the adsorbed state changed more than that of N2O in [Ag]-SAPO-5 and [Ag]-TAPO-5.Moreover,[Ag]-SAPO-5 and [Ag]-TAPO-5 had a higher activation for the NOx molecule compared to [Ag]-AlMOR.The resistance capabilities of [Ag]-SAPO-5 and [Ag]-TAPO-5 to SO2,H2O,and O2 were also studied and analyzed.In addition,the interaction mechanism of NOx in silver-exchanged aluminophosphate molecular sieves was investigated using natural bond orbital（NBO） analysis.