Formation and dehydration enthalpy of gallosilicate zeolites
Formation and dehydration enthalpy of gallosilicate zeolites
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没食子硅酸盐沸石的形成和脱水焓
DOI：
10.1016/j.micromeso.2007.08.043
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
A. Navrotsky
中科院分区：
文献类型：
--
作者：
P. Sun;A. Navrotsky
合成了Ga-NaSOD、Ga-NaFAU、Ga-NaNAT、Ga-KNAT*（Ga-KNAT和Ga-KTNU-2的混合物）、Ga-KLTL和Ga-KTNU-1等镓硅酸盐分子筛，并通过X射线衍射（XRD）、微探针分析、热重分析和差示扫描量热（TG-DSC）对其进行了表征。一般情况下，除了Ga-KNAT* 外，Ga替代Al后，晶格参数增加。用高温氧化物熔体溶液量热法测定了这些沸石的生成和脱水性能。与具有相似Si/T3+的类似铝硅酸盐沸石相比，镓硅酸盐沸石具有相似的每摩尔四面体的脱水焓，但由于Ga沸石的扩大晶胞中的H2O分子的数目较大，因此具有较少的每摩尔水的吸热脱水焓。每摩尔水的脱水焓是骨架密度的单调函数，而每摩尔四面体的脱水焓主要受阳离子类型的影响。镓硅酸盐沸石具有比类似的铝硅酸盐沸石更少的来自氧化物组分的放热形成碎片，证实了它们的较低稳定性。水化和脱水镓硅酸盐沸石的形成周期与Ga/（Ga+Si）比和骨架密度（FD）有关。
Gallosilicate zeolites Ga-NaSOD, Ga-NaFAU, Ga-NaNAT, Ga-KNAT* (a mixture of Ga-KNAT and Ga-KTNU-2), Ga-KLTL and Ga-KTNU-1 have been synthesized and characterized by X-ray diffraction (XRD), microprobe analysis, thermogravimetric analysis and differential scanning calorimetry (TG-DSC). Generally, the lattice parameters increase after Ga substitution for Al, except for Ga-KNAT*. The formation and dehydration enthalpies of these zeolites were measured by high temperature oxide melt solution calorimetry. Compared to the analogous aluminosilicate zeolite of similar Si/T3+, the gallosilicate zeolite has similar dehydration enthalpy per mole of tetrahedra, but has less endothermic dehydration enthalpy per mole of water due to the larger number of H2O molecules in the enlarged unit cell of the Ga zeolite. The dehydration enthalpy per mole of water is a monotonic function of framework density while that per mole of tetrahedra is mainly influenced by cation type. The gallosilicate zeolites have less exothermic formation enthalpies from oxide components than the analogous aluminosilicate zeolites, confirming their lower stability. The formation enthalpies of hydrated and dehydrated gallosilicate zeolites are correlated with Ga/(Ga+Si) ratio and framework density (FD).
影响因子：
1.6
作者：
T. Nagase;A. Chatterjee;A. Tanaka;M. A. L. Tanco;K. Tazaki
通讯作者：
T. Nagase;A. Chatterjee;A. Tanaka;M. A. L. Tanco;K. Tazaki