Fe-containing zeolite catalysts are active in N₂O decomposition and direct oxidation of unreactive methane. Except for the well-known ability that acid sites realize the subsequent reaction of methanol to hydrocarbon, the roles of acidic protons in the direct oxidation of methane have not been studied regarding the formation of active Fe components and the reactivity in the reaction. Herein, on the premise of the comparable total Fe and Al contents, the acidity of one-pot synthesized Fe-AEI and ion-exchanged Fe/AEI zeolites was adjusted by various Na contents, and the catalytic activity in methane oxidation reactions was compared under different conditions. Ultraviolet–visible (UV–vis) spectra at 25–500 °C of the as-synthesized Fe-AEI and the reaction performance at the corresponding conditions were combined to clarify the formation of potential active Fe species. Acidic proton was favorable for the formation of potential active Fe species for the one-pot synthesized Fe-AEI zeolite. However, for the H-type Fe/AEI zeolite, thermal treatment at high temperatures was prone to dealuminate, reduced the number of anchors for Fe³⁺ attachment, and resulted in inactive Fe_xO_y. Furthermore, in contrast to the robust N₂O adsorption capacity of Na⁺, the acidic proton exhibited weak competition with Fe³⁺ for N₂O adsorption and thus contributed to the higher activity in the methane oxidation reaction. Our findings highlighted the importance of the acidic proton for the formation of potential active Fe species, the frail competition of adsorption N₂O with Fe species, and the feasibility of the tandem reaction of methane to methanol and methanol to hydrocarbon.

中文翻译：

---

含铁沸石的酸性质子在甲烷直接氧化中的作用


含铁沸石催化剂在 N₂O 分解和未反应性甲烷的直接氧化中具有活性。除了众所周知的酸位点实现甲醇与碳氢化合物的后续反应的能力外，酸性质子在甲烷直接氧化中的作用尚未研究过活性 Fe 组分的形成和反应性。本文在总 Fe 和 Al 含量相当的前提下，通过各种 Na 含量调节一锅合成的 Fe-AEI 和离子交换的 Fe/AEI 分子筛的酸度，并比较了不同条件下甲烷氧化反应中的催化活性。将合成的 Fe-AEI 在 25–500 °C 下的紫外-可见光 （UV-vis） 光谱和相应条件下的反应性能相结合，以阐明潜在活性 Fe 物种的形成。酸性质子有利于一锅法合成的 Fe-AEI 沸石潜在活性 Fe 种类的形成。然而，对于 H 型 Fe/AEI 分子筛，高温热处理容易脱离，减少了 Fe³⁺ 附着的锚栓数量，并导致 Fe_xO_y 失活。此外，与 Na⁺ 强大的 N₂O 吸附能力相比，酸性质子与 Fe³⁺ 对 N₂O 的吸附表现出弱竞争，因此有助于在甲烷氧化反应中具有更高的活性。我们的研究结果强调了酸性质子对潜在活性 Fe 物种形成的重要性、吸附 N₂O 与 Fe 物种的脆弱竞争，以及甲烷与甲醇和甲醇与碳氢化合物串联反应的可行性。