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Ray L. Frost Anthony W. Musumeci Thor Bostrom Moses O. Adebajo Matt L. Weier Wayde Martens 《Thermochimica Acta》2005,429(2):179-187
The thermal decomposition of hydrotalcites with chromate, molybdate and sulphate in the interlayer has been studied using thermogravimetric analysis coupled to a mass spectrometer measuring the gas evolution. X-ray diffraction shows the hydrotalcites have a d(0 0 3) spacing of 7.98 Å with very small differences in the d-spacing between the three hydrotalcites. XRD was also used to determine the products of the thermal decomposition. For the sulphate-hydrotalcite decomposition the products were MgO and a spinel MgAl2O4, for the chromate interlayered hydrotalcite MgO, Cr2O3 and spinel. For the molybdate interlayered hydrotalcite the products were MgO, spinel and MgMoO4. EDX analyses enabled the formula of the hydrotalcites to be determined. Two processes are observed in the thermal decomposition namely dehydration and dehydroxylation and for the case of the sulphate interlayered hydrotalcite, a third process is the loss of sulphate. Both the dehydration and dehydroxylation take place in three steps each for each of the hydrotalcites. 相似文献
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Frost RL Erickson KL Kloprogge TJ 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,61(13-14):2919-2925
Raman spectroscopy has been used to study the nitrate hydrotalcite mbobomkulite NiAl2(OH)16(NO3).4H2O. Mbobomkulite along with hydrombobomkulite and sveite are known as 'cave' minerals as these hydrotalcites are only found in caves. Two types of nitrate anion are observed using Raman spectroscopy namely free or non-hydrogen bonded nitrate and nitrate hydrogen bonded to the interlayer water and to the 'brucite-like' hydroxyl surface. Two bands are observed in the Raman spectrum of Ni-mbobomkulite at 3576 and 3647 cm(-1) with an intensity ratio of 3.36/7.37 and are attributed to the Ni3OH and Al3OH stretching vibrations. The observation of multiple water stretching vibrations implies that there are different types of water present in the hydrotalcite structure. Such types of water would result from different hydrogen bond structures. 相似文献
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