Fujiyama Shinjiro, Yoza Kenji, Kamiya Natsumi, Nishi Koji, Yokomori Yoshinobu
Applied Chemistry, National Defense Academy, Hashirimizu, Yokosuka, Kanagawa, Japan.
Bruker AXS, Yokohama, Kanagawa, Japan.
Acta Crystallogr B Struct Sci Cryst Eng Mater. 2015 Feb;71(Pt 1):112-8. doi: 10.1107/S2052520615000256. Epub 2015 Feb 1.
The entrance and diffusion pathway of CO2 and dimethyl ether (DME) in MFI-type zeolite channels were investigated by a selective sealing method using large silicalite-1 crystals. The MFI-type zeolite has two kinds of orthogonal channels: straight channels and sinusoidal channels. The mouths of the straight channels are on (010) crystal faces, while those of the sinusoidal channels are on (100) faces. The channel mouths are directly sealed by silicone resin on the (100) and (010) faces so as to restrict the entrance and diffusion pathways to straight and sinusoidal channel pathways, respectively. The locations and loadings of the guest CO2 and DME molecules are determined by single-crystal X-ray diffraction structural analysis. The loadings show the difference of the adsorption rates between the pathways. The straight channel pathway is 4.2 times faster than the sinusoidal channel pathway for the CO2, and the sinusoidal channel pathway is 5.1 times faster than the straight channel pathway for the DME. It reveals their dominant pathways and the anisotropy of adsorption. The dominant pathway correlates to the stability of the channel as adsorption sites.
采用大尺寸硅沸石-1晶体的选择性密封方法，研究了二氧化碳（CO₂）和二甲醚（DME）在MFI型沸石通道中的入口和扩散路径。MFI型沸石有两种正交通道：直通道和正弦通道。直通道的口位于（010）晶面上，而正弦通道的口位于（100）面上。通过硅树脂直接在（100）和（010）面上密封通道口，从而分别将入口和扩散路径限制为直通道路径和正弦通道路径。客体CO₂和DME分子的位置和负载量通过单晶X射线衍射结构分析确定。负载量显示了不同路径之间吸附速率的差异。对于CO₂，直通道路径的吸附速率比正弦通道路径快4.2倍；对于DME，正弦通道路径的吸附速率比直通道路径快5.1倍。这揭示了它们的主要扩散路径以及吸附的各向异性。主要扩散路径与作为吸附位点的通道稳定性相关。
