Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
J Environ Sci (China). 2011;23(4):681-6. doi: 10.1016/s1001-0742(10)60482-2.
The adsorption and desorption of N2O on main-group ion-exchanged ZSM-5 was studied using temperature-programmed desorption (TPD) and density functional theory (DFT) calculations. TPD experiments were carried out to determine the desorbed temperature Tmax corresponding to the maximum mass intensity of N2O desorption peak and adsorption capacity of N2O on metal-ion-exchanged ZSM-5s. The results indicated that Tmax followed a sequence of Ba2+ > Ca2+ > Cs+ > K+ > Na+ > Mg2+ and the amount of adsorbed N2O on main-group metal cation followed a sequence of Ba2+ > Mg2+ > Ca2+ > Na+ > K+ > Cs+. The DFT calculations were performed to obtain the adsorption energy (Eads), which represents the strength of the interaction between metal cations and the N-end or O-end of N2O. The calculation results showed that the N-end of the N2O molecule was favorably adsorbed on ion-exchanged ZSM-5, except for Cs-ZSM-5. For alkali metal cations, the Eads of N2O on cations followed the order which was the same to that of Tmax: Cs+ > K+ > Na+. The calculated and experimental results consistently showed that the adsorption performances of alkaline-earth metal cations were better than those of alkali metal cations.
采用程序升温脱附（TPD）和密度泛函理论（DFT）计算研究了 N2O 在主族离子交换 ZSM-5 上的吸附和解吸。通过 TPD 实验确定了与 N2O 解吸峰最大质量强度相对应的脱附温度 Tmax 和金属离子交换 ZSM-5 上 N2O 的吸附容量。结果表明，Tmax 遵循 Ba2+ > Ca2+ > Cs+ > K+ > Na+ > Mg2+的顺序，主族金属阳离子上吸附的 N2O 量遵循 Ba2+ > Mg2+ > Ca2+ > Na+ > K+ > Cs+的顺序。进行了 DFT 计算以获得吸附能（Eads），它表示金属阳离子与 N2O 的 N 端或 O 端之间相互作用的强度。计算结果表明，N2O 分子的 N 端优先吸附在离子交换的 ZSM-5 上，除了 Cs-ZSM-5 以外。对于碱金属阳离子，N2O 在阳离子上的 Eads 顺序与 Tmax 相同：Cs+ > K+ > Na+。计算和实验结果一致表明，碱土金属阳离子的吸附性能优于碱金属阳离子。
