J. Heyrovský Institute of Physical Chemistry of the Academy of Sciences of the Czech Republic, Dolejškova 3, 182 23 Prague 8, Czech Republic.
Chemphyschem. 2013 Feb 25;14(3):520-31. doi: 10.1002/cphc.201200900. Epub 2013 Jan 14.
The role of framework oxygen atoms in N(2)O decomposition [N(2)O(g)→N(2)(g) and 1/2O(2)(g)] over Fe-ferrierite is investigated employing a combined experimental (N(2)(18)O decomposition in batch experiments followed by mass spectroscopy measurements) and theoretical (density functional theory calculations) approach. The occurrence of the isotope exchange indicates that framework oxygen atoms are involved in the N(2)O decomposition catalyzed by Fe-ferrierite. Our study, using an Fe-ferrierite sample with iron exclusively present as Fe(II) cations accommodated in the cationic sites, shows that the mobility of framework oxygen atoms in the temperature range: 553 to 593 K is limited to the four framework oxygen atoms of the two AlO(4)(-) tetrahedra forming cationic sites that accomodate Fe(II). They exchange with the Fe extra-framework (18)O atom originating from the decomposed N(2)(18)O. We found, using DFT calculations, that O(2) molecules facilitate the oxygen exchange. However, the corresponding calculated energy barrier of 87 kcal mol(-1) is still very high and it is higher than the assumed experimental value based on the occurrence of the sluggish oxygen exchange at 553 K.
采用实验（批处理实验中 N2(18)O 的分解，随后进行质谱测量）和理论（密度泛函理论计算）相结合的方法，研究了 N2O 分解[ N2O（g）→N2（g）和 1/2O2（g）]在 Fe-丝光沸石上的作用。同位素交换的发生表明，框架氧原子参与了 Fe-丝光沸石催化的 N2O 分解。我们的研究使用的是一种 Fe-丝光沸石样品，其中的铁仅以 Fe(II)阳离子的形式存在于阳离子位中，表明在 553 至 593 K 的温度范围内，框架氧原子的迁移性仅限于形成阳离子位的两个 AlO4(-)四面体的四个框架氧原子，这些阳离子位容纳 Fe(II)。它们与来自分解的 N2(18)O 的 Fe 架外（18）O 原子发生交换。我们通过 DFT 计算发现，O2 分子促进了氧交换。然而，相应的计算能垒为 87 kcal mol(-1)仍然非常高，并且高于基于 553 K 时缓慢的氧交换发生而假设的实验值。
