Alkaline-Earth Oxide Nanoparticles Obtained by Aerogel Methods. Characterization and Rational for Unexpectedly High Surface Chemical Reactivities

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• 作者：Olga B. Koper ; Isabelle Lagadic ; Alexander Volodin ; and Kenneth J. Klabunde
• 刊名：Chemistry of Materials
• 出版年：1997
• 出版时间：November 1997
• 年：1997
• 卷：9
• 期：11
• 页码：2468 - 2480
• 全文大小：809K
• 年卷期：v.9,no.11(November 1997)
• ISSN：1520-5002

文摘

Aerogel preparation of MgO and CaO nanoparticles involves asol-gel approach wheremethoxides are converted to hydroxide gels followed by hypercriticaldrying and vacuumdehydration. This produces, for these particularhydroxides/oxides, ultrafine particulatesrather than monoliths. These particulate materials have exhibitedunexpectedly high surfacechemical reactivities that have allowed their successful use ashigh-capacity destructiveadsorbents for toxic chemicals, including chlorocarbons,organophosphorus compounds, andacid gases. Detailed characterization involving X-ray diffraction(XRD), gas adsorption/pore distribution analysis, infrared, TEM, AFM, XPS, probe moleculeadsorption, andelemental analysis has allowed a rationale to be developed that helpsexplain the highchemical reactivities observed, especially for CaO. Pore volumeand size distribution, unusualsurface morphologies with a high ratio of edge ion/surface ions, andtrace residual (persistent)surface -OH and -OCH₃ seem to be the main factorsallowing these nanoparticulates to beisolable and stable and yet highly reactive, and results for CaO areemphasized herein.