Ramos Francisca S O, Pastore Heloise O
Micro and Mesoporous Molecular Sieves Group, Institute of Chemistry, University of Campinas, 270, Monteiro Lobato St., University Campus, Campinas, 13083-862, SP, Brazil.
Dalton Trans. 2017 Sep 12;46(35):11728-11737. doi: 10.1039/c7dt02241g.
Al heteroions have been incorporated into the silicate layers of Na-RUB-18 in three different molar ratios Si/Al (22, 40 and 42) through a post-synthesis procedure under hydrothermal conditions. Systematic characterization (XRD, Si NMR, Al NMR and SEM) showed that these Na-[Al]-RUB-18 layered aluminosilicates are free from impurities, and the aluminum did not affect the crystallinity of the material, and also did not change its morphology. Al NMR showed that aluminum was incorporated in the tetrahedral position and the layered sample with molar ratio Si/Al = 22 has also displayed octahedral coordination. These layered aluminosilicates which consist of lamella stacking in the c direction had their interlayer space expanded by ion exchange with CTA. The swollen samples were pillared with TEOS, as the SiO pillar precursor, and octylamine, as the hydrolyzing agent and co-surfactant. Pillared materials presented type IV isotherms with a BET surface area in the range of 223-323 m g and mesoporous with 2-4 nm, while their layered precursors Na-[Al]-RUB-18 showed type II isotherms with a BET surface area in the range of 7-12 m g. Additionally, the acidity present in the layers of these pillared solids was proved by in situ ethanol dehydration monitored by FTIR.
通过水热条件下的后合成程序，已将三种不同摩尔比Si/Al（22、40和42）的杂离子掺入Na-RUB-18的硅酸盐层中。系统表征（XRD、Si NMR、Al NMR和SEM）表明，这些Na-[Al]-RUB-18层状铝硅酸盐不含杂质，铝不影响材料的结晶度，也不改变其形态。Al NMR表明铝掺入四面体位置，摩尔比Si/Al = 22的层状样品还显示出八面体配位。这些由沿c方向的薄片堆叠组成的层状铝硅酸盐通过与CTA进行离子交换使其层间空间扩大。用TEOS作为SiO柱前驱体，用辛胺作为水解剂和共表面活性剂对溶胀的样品进行柱撑。柱撑材料呈现IV型等温线，BET表面积在223 - 323 m²/g范围内，且具有2 - 4 nm的介孔，而其层状前驱体Na-[Al]-RUB-18呈现II型等温线，BET表面积在7 - 12 m²/g范围内。此外，通过FTIR监测原位乙醇脱水证明了这些柱撑固体层中存在酸性。
