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International Center for Materials Nanoarchitectonics (WPI-MANA)

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[[Research Highlights Vol.49] Porous Structure of a Layered Silicate with Selective Adsorption Properties Revealed](https://mdr.nims.go.jp/datasets/94e1fa10-140a-4d84-95ab-7ed2cb008c0a)

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2022/03/31 16:27 Porous Structure of a Layered Silicate with Selective Adsorption Properties Revealed| MANAhttps://www.nims.go.jp/mana/research/highlights/vol49.html 1/2Previous  Index  NextResearch Highlights[Vol. 49]Porous Structure of a Layered Silicate with Selective Adsorption PropertiesRevealed20 Mar, 2019Figure: The structure of magadiite features pores that have a selective adsorption function.It is not always easy to precisely determine the crystal structure of layered materials — but inorder to fully understand and exploit their properties, detailed structural information is needed.Magadiite is such a layered material, used as an adsorbent and a catalyst. It is known thatmagadiite is a kind of layered silicates: tetrahedra, each with oxygen atoms at the vertices and asilicon atom in the center, grouped in planar arrangements. The precise structure, however, wasnot known — partly because the material typically occurs as small lamellas displaying poorcrystallinity — until now. Satoshi Tominaka at the International Center for MaterialsNanoarchitectonics (MANA), National Institute for Materials Science (NIMS), Tsukuba, Japan, andcolleagues have succeeded in determining the crystal structure of magadiite. Based on theirstructural insights, Yusuke Ide (MANA, NIMS) and colleagues also managed to explain why thematerial has outstanding photocatalytic properties and proved its application in the synthesis ofpure benzoic acid from toluene using a photocatalyst system.The researchers looked at Na-magadiite (the natural, sodium-containing form) and H-magadiite(the ‘protonated’ form, obtained by removing sodium). By collecting X-ray diffraction data andusing a method called pair-distribution-function analysis, they were able to come up with ahttps://www.nims.go.jp/mana/research/highlights/vol48.htmlhttps://www.nims.go.jp/mana/research/highlights/index.htmlhttps://www.nims.go.jp/mana/research/highlights/vol50.html2022/03/31 16:27 Porous Structure of a Layered Silicate with Selective Adsorption Properties Revealed| MANAhttps://www.nims.go.jp/mana/research/highlights/vol49.html 2/2structural model. Importantly, they found that in Na-magadiite, along the silicate layers,micropores filled with sodium atoms occur. Removing the Na content (by acid treatment) resultedin a structure with channels.The porosity of H-magadiite was confirmed by looking at nitrogen gas (N2) adsorption.N2 molecules can enter the pores; the size of the pores was estimated to be around half ananometre.The team also found that although the pores in H-magadiite are small, they can absorb benzoicacid (C6H5COOH). This property is of high importance in the photocatalytic synthesis of benzoicacid from toluene (C6H5CH3), with titanium oxide (TiO2) as a catalyst. By letting the synthesis takeplace in an environment with H-magadiite, the yield of benzoic acid was much higher than normal;the explanation is that the pores of H-magadiite temporarily store the C6H5COOH molecules.Now that the full structure of magadiite has been established — including the geometry of themicropores along the thin silicate layers — further applications of the material can be investigated.Quoting the scientists: “These structural features of magadiite are expected to create advancedapplications of magadiite as we demonstrated [for the case of benzoic acid production withmagadiite as a selective adsorbent].”Reference“Zeolitic intralayer microchannels of magadiite, a natural layered silicate, to boost green organicsynthesis”Yusuke Ide, Satoshi Tominaka, Hiroyuki Kono, Rahul Ram, Akihiko Machida, and Nao TsunojiJournal : Chem. Sci. 9 8637 (2018).DOI : 10.1039/c8sc03712dAffiliationsInternational Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for MaterialsScience (NIMS), Namiki 1-1, Tsukuba, Ibaraki 305-0044, JapanContact informationInternational Center for Materials Nanoarchitectonics(WPI-MANA)National Institute for Materials Science1-1 Namiki, Tsukuba, Ibaraki 305-0044 JapanPhone: +81-29-860-4710E-mail: mana-pr[AT]ml.nims.go.jphttps://samurai.nims.go.jp/profiles/ide_yusuke?locale=enhttps://samurai.nims.go.jp/profiles/tominaka_satoshi?locale=enhttps://pubs.rsc.org/en/content/articlelanding/2018/SC/C8SC03712D#!divAbstract