Alkaline-earth oxide nanoparticles obtained by aerogel methods. Characterization and rational for unexpectedly high surface chemical reactivities

被引:153
作者
Koper, OB [1 ]
Lagadic, I [1 ]
Volodin, A [1 ]
Klabunde, KJ [1 ]
机构
[1] KANSAS STATE UNIV, DEPT CHEM, MANHATTAN, KS 66506 USA
关键词
D O I
10.1021/cm970357a
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Aerogel preparation of MgO and CaO nanoparticles involves a sol-gel approach where methoxides are converted to hydroxide gels followed by hypercritical drying and vacuum dehydration. This produces, for these particular hydroxides/oxides, ultrafine particulates rather than monoliths. These particulate materials have exhibited unexpectedly high surface chemical reactivities that have allowed their successful use as high-capacity destructive adsorbents for toxic chemicals, including chlorocarbons, organophosphorus compounds, and acid gases. Detailed characterization involving X-ray diffraction (XRD), gas adsorption/pore distribution analysis, infrared, TEM, AFM, XPS, probe molecule adsorption, and elemental analysis has allowed a rationale to be developed that helps explain the high chemical reactivities observed, especially for CaO. Pore volume and size distribution, unusual surface morphologies with a high ratio of edge ion/surface ions, and trace residual (persistent) surface -OH and -OCH3 seem to be the main factors allowing these nanoparticulates to be isolable and stable and yet highly reactive, and results for CaO are emphasized herein.
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页码:2468 / 2480
页数:13
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