A Thermal Study of Al-Pillared Montmorillonites
| Autor: | Hong Yan Xu, Xing Tong Chen |
|---|---|
| Rok vydání: | 2011 |
| Předmět: |
Thermogravimetric analysis
Materials science Yield (engineering) General Engineering Mineralogy Hydrothermal circulation law.invention chemistry.chemical_compound Differential scanning calorimetry Montmorillonite chemistry Chemical engineering law Calcination Fourier transform infrared spectroscopy BET theory |
| Zdroj: | Advanced Materials Research. 187:112-116 |
| ISSN: | 1662-8985 |
| DOI: | 10.4028/www.scientific.net/amr.187.112 |
| Popis: | Al-pillared montmorillonites (Al-MMT) were synthesized from naturally occurring sodium montmorillonite through exchange of interlamellar ions with hydroxyalumina polycations. Furthermore, Powder X-ray diffraction (XRD), Fourier transformation infra-red spectra (FTIR), Thermogravimetric analysis (TG), and differential scanning calorimetry (DSC) were applied in order to study the themal stability, hydrothermal stability and synthesis mechanisms of pillared materials. The Al-MMT are thermally stable and hydrothermal stability up to700°C. X-ray diffractograms of Al-MMT calcined at 700 0C show a sharp and intense d001 peak, corresponding to a basal spacing of 1.66nm. Until calcinations at 8000C, the pillared clays generally retain their structural ordering as evidenced by a broad basal (001) peak, which is an indication that the layer structure lost some long-range ordering. In a 100% steam flow under atmospheric pressure at 7000C, the characteristic d001 spacing of Al-MMT decreases from 1.83nm to 1.71nm, intensity of basal peak reduced by58%. However, after hydrothermal at 8000C, the basal (001) peak is not observed, indicating a complete structural collapse. Synthesis mechanisms for Al-MMT are established. Some of tetrahedral silicons or aluminums inverse towards gallery to react with pillaring agents and yield Alp-O-AlsⅣ or Alp-O-Sis bridges which would firmly fix the pillars to the host clay. |
| Databáze: | OpenAIRE |
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