Journal of the Clay Science Society of Japan (in Japanese)

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Smectite-type porous materials having catalytically active metal cations in octahedral sheets are prepared from metal chloride and water glass with a hydrothermal method. The pore structure (surface area, pore volume and pore diameter) of the porous materials can be controlled by adjusting pH values and the addition of quaternary alkyl ammonium salts during the hydrothermal synthesis. In this manuscript, the synthesis of smectite-type porous materials is briefly described, and their catalysis and catalyst support properties for commercially important reactions are introduced. In the part of the catalysis, 1-butene isomerization, carbon dioxide insertion, and desulfurization activities of smectite-type porous materials having divalent cations (Ni^2＋, Mg^2＋, and Co^2＋) and alkali cations (Li^＋, Na^＋ and K^＋) are described. In the part of the support usage, n-butane hydrogenolysis over platinum metal particles supported on smectite-type porous materials having divalent cations (Ni^2＋, Mg^2＋, and Co^2＋), and hydrogenation of acrylonitrile-butadiene rubber in organic solvents over palladium metal particles supported on pore-size-controlled smectite-type porous materials.

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The four smectite clays in the CSSJ reference samples have been examined using TEM/STEM imaging and energy dispersive X-ray spectroscopy (EDS) in SEM and STEM, to characterize their chemical compositions, grain sizes, impurity minerals, and other properties. Fine calcite particles were commonly found along with quartz in the Tsukinuno samples (JCSS-3101, 3101b), which serve as the primary source of calcium as reported in previous bulk analyses. Cristobalite, quartz, and feldspar are prevalent impurity minerals in the Mikawa sample (JCSS-3102), and the STEM-EDS analysis revealed that the composition of the smectite clay is definitely montmorillonite with subtle difference from the Tsukinuno montmorillonite. The synthetic saponite (JCSS-3501) displayed a wide range of crystal sizes. Sulfate and sodium ions are concentrated in the aggregates of very fine saponite crystallites compared to the saponite particles with larger sizes.

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