介孔硅层柱蒙脱石材料合成的新方法与表征

利用十六烷基三甲基溴化铵(CTAB)将天然钠基蒙脱石改性成有机蒙脱石,以十二烷胺为模板剂,正硅酸乙酯为层柱前驱体,在室温下合成了新型介孔硅层柱蒙脱石材料.用XRD,TG,FTIR以及N₂等温吸附-脱附等技术对产物进行了表征.结果表明,合成材料具有大通道(净层间距为2.75nm)、介孔孔径且孔分布窄(平均孔径为2.17nm)、比表面积高(SBET=821.6m²/g)、热稳定性高(大于800℃)等特征.同时,通过改变中性胺的链长,研究了孔结构的调变规律,分析了材料的成孔机理和热稳定性提高的原因.

A Novel Method for Preparing Mesoporous Silica Pillared Montmorillonite Material and Its Structure Characterization

The mesoporous silica pillared clays, with porous montmorillonite(MMT) heterostructures, were synthesized by pillaring and template-assembly techniques.The purified MMTis modified by cetyltrimethylammonium bromide(CTAB).Mixtures of the modified MMT, dodecylamine(DDA) and tetraethylorthosilicate(TEOS) at MMT/DDA/TEO Smolar ratios of 1∶20∶150 were allowed to react for8h.Then the resulted intercalates were centrifuged and dried in air.Finally after calcination at 540 ℃ for {4 h} to remove the organic templates, the novel silica porous MMTheterostructures(PMHs) were obtained.The resulted PMHs were characterized by XRD, TG, FTIRand N2adsorption-desorption isotherms.The results indicate that the PMHs possess mesopore(average pore size of 2.17 nm), super-gallery height of 2.75 nm, a large BETspecific surface area of 821.6m2/g and high thermal stability up to 800℃. Through changing the chain length of neutral amine used, the adjustment of pore and gallery height of PMHs has been explored.The mechanism of pore formation through gallery template-assembly was postulated, and the higher thermal stability of PMHs was ascribed to uniformity of pillars.