Abstract DNL-6, a silicoaluminophosphate (SAPO) molecular sieve with RHO topology, was hydrothermally synthesized using a new structure-directing agent (SDA), N,N′-dimethylethylenediamine. The obtained samples were characterized by X-ray diffraction, X-ray fluorescence, X-ray photoelectron spectroscopy, scanning electron microscopy, and N2 adsorption, which indicated that the synthesized DNL-6s have high crystallinity and relatively high Si content ranging from 20% to 35%. Solid-state magic-angle-spinning (MAS) nuclear magnetic resonance (13C, 29Si, 27Al, 31P, and 27Al multiple-quantum (MQ)) was conducted to investigate the status of the SDA and local atomic environment in the as-synthesized DNL-6. Thermal analysis revealed the presence of a large amount of amines in the DNL-6 crystals (about 4.4 SDAs per α-cage), which was the reason for the formation of DNL-6 with an ultrahigh Si content (36.4% Si per mole). Interestingly, DNL-6 exhibited excellent catalytic performance for methanol amination. More than 88% methanol conversion and 85% methylamine plus dimethylamine selectivity could be achieved due to the combined contribution of strong acid sites, suitable acid distribution, and narrow pore dimensions of DNL-6.

中文翻译：

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磷酸硅铝分子筛DNL-6：新型模板剂N,N'-二甲基乙二胺的合成及其催化应用

摘要 DNL-6 是一种具有 RHO 拓扑结构的硅铝磷酸盐 (SAPO) 分子筛，采用新型结构导向剂 (SDA) N,N'-二甲基乙二胺水热合成。所得样品通过 X 射线衍射、X 射线荧光、X 射线光电子能谱、扫描电子显微镜和 N2 吸附表征，表明合成的 DNL-6s 具有较高的结晶度和较高的 Si 含量，范围为 20%到 35%。进行固态魔角自旋 (MAS) 核磁共振（13C、29Si、27Al、31P 和 27Al 多量子 (MQ)）以研究合成中 SDA 和局部原子环境的状态DNL-6。热分析显示 DNL-6 晶体中存在大量胺（每个 α-笼约 4.4 个 SDA），这就是形成具有超高 Si 含量（每摩尔 36.4% Si）的 DNL-6 的原因。有趣的是，DNL-6 表现出优异的甲醇胺化催化性能。由于 DNL-6 的强酸位、合适的酸分布和窄孔尺寸的综合贡献，可以实现超过 88% 的甲醇转化率和 85% 的甲胺加二甲胺选择性。