Cross-Linked Smectites. V. Synthesis and Properties of Hydroxy-Silicoaluminum Montmorillonites and Fluorhectorites
Cross-Linked Smectites. V. Synthesis and Properties of Hydroxy-Silicoaluminum Montmorillonites and Fluorhectorites
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交联蒙皂石。
DOI：
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发表时间：
1987
期刊：
影响因子：
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通讯作者：
J. Shabtai
中科院分区：
文献类型：
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作者：
J. Sterte;J. Shabtai
通过两个步骤制备含有羟基-SiAl（HSA）寡阳离子的溶液：（1）用NaOH水溶液处理原酸和AlCl 3的混合物，然后老化产物;和（2）羟基-Al 13寡阳离子的初步制备和老化，然后后者与原酸反应。Na，Ca-蒙脱石与HSA低聚阳离子的离子交换产生了柱撑交联蒙脱石（命名为HSA-CLM），风干样品的最大d（001）值为19.5 μ m，在250°C/10−3 μ m脱气后的最大表面积约为500 m2/g。Li-氟锂蒙脱石的相应离子交换产生HSA氟锂蒙脱石（HSA-CLFH），其显示最大d（001）值为19.0 μ m，表面积为355 m2/g。HSA-CLM和HSA-CLFH产品的计算结构式，基于元素分析，表明随着柱撑溶液中Si/Al比的增加，插层HSA寡阳离子中的Si/Al比逐渐增加。使用方法2和应用1.6-2.5 mmole（Si）Al/g蒙脱石的比率获得HSA-CLM和HSA-CLFH产品的最佳d（001）值和表面积。通过在250°和700°C之间热处理和随后测量d（001）值和表面积来确定HSA-CLM和HSA-CLFH产品的热稳定性。HSA-CLFH产物的d（001）值在400° ~ 500°C范围内随温度升高而增加，在500° ~ 600°C范围内基本保持不变。HSA-CLM产物显示出表面积逐渐减小，而在柱化溶液中以1.04-2.18的Si/Al比制备的HSA-CLFH产物随着温度从250° C增加至600°C显示出恒定的表面积。HSA-CLM和HSA-CLFH显示出比通过用羟基-Al 13寡阳离子柱撑获得的参考Al-CLM和Al-CLFH样品更高的酸度。这种增加的酸度可能是由于在HSA寡聚阳离子中存在酸性表面硅烷醇基团。
Solutions containing hydroxy-SiAl (HSA) oligocations were prepared by two procedures: (1) treatment of a mixture of orthosilicic acid and AlCl3 with aqueous NaOH, followed by aging of the product; and (2) preliminary preparation and aging of hydroxy-Al13 oligocations followed by reaction of the latter with orthosilicic acid. Ion exchange of Na,Ca-montmorillonite with HSA oligocations yielded pillared, cross-linked montmorillonites (designated as HSA-CLM) showing a maximum d(001) value of 19.5 Å for air-dried samples, and maximum surface areas of ~500 m2/g after outgassing at 250°C/10−3 torr. Corresponding ion exchange of Li-fluorhectorite yielded HSA fluorhectorites (HSA-CLFH) showing a maximum d(001) value of 19.0 Å and a surface area of 355 m2/g. Calculated structural formulae for the HSA-CLM and HSA-CLFH products, based on elemental analysis, showed a gradual increase in the Si/Al ratio in the intercalated HSA oligocations with increasing Si/Al ratio in the pillaring solution. Optimum d(001) values and surface areas of HSA-CLM and HSA-CLFH products were obtained using method 2 and applying a ratio of 1.6–2.5 mmole (Si)Al/g smectite.The thermal stabilities of HSA-CLM and HSA-CLFH products were determined by heat treatment between 250° and 700°C and subsequent measurement of the d(001) values and surface areas. HSA-CLFH products showed the unusual behavior of increase of d(001) with increase in temperature from 400° to 500°C, and essential constancy of d(001) from 500° to 600°C. The HSA-CLM products showed a gradual decrease in surface area, whereas the HSA-CLFH products prepared with a Si/Al ratio of 1.04–2.18 in the pillaring solution showed constant surface areas with increasing temperature from 250° to 600°C. HSA-CLM and HSA-CLFH show sharply higher acidities compared with those of reference Al-CLM and Al-CLFH samples obtained by pillaring with hydroxy-Al13 oligocations. This increased acidity is probably due to the presence of acidic, surface silanol groups in the HSA oligocations.