Interlayer Expansion of the Layered Zeolite Precursor RUB-39: A Universal Method To Synthesize Functionalized Microporous Silicates
Gies, Hermann × Mueller, Ulrich Yilmaz, Bilge Tatsumi, Takashi Xie, Bin Xiao, Feng-Shou Bao, Xinhe Zhang, Weiping De Vos, Dirk #
American Chemical Society
Chemistry of Materials vol:23 issue:10 pages:2545-2554
Interlayer expansion reaction leads to a new family of microporous framework silicates using hydrous layer silicates as precursors. Using silylating agents such as dichlor-dimethylsilane (DCDMS), neighboring layers connect. In addition to the topotactic condensation of hydrous silicates, this leads to expanded silicate frameworks, with the number of pore openings increased by two Si-units. The hydrous layer silicate RUB-39 has been subjected to interlayer expansion reaction, using DCDMS at 180 degrees C, yielding new, crystalline microporous frameworks (COE-1 and COE-2), varying in their methyl function carrying as-made and oxidized calcined forms, respectively. An intersecting two-dimensional (2D) channel system with 10- and 12-membered rings is accessible for probe molecules, leading to a surface area of 540 m(2)/g and a pore volume of 0.169 cm(3)/g. The powder diagram was indexed in space group P2 with a = 15.609(3) angstrom, b = 11.163(1) angstrom, c= 7.301(1) angstrom, and beta = 91.2(1)degrees for COE-1 and a = 15.594(4) angstrom, b = 11.039(2) angstrom, c = 7.276(1) angstrom, and beta = 91.2(1)degrees for calcined COE-2. Rietveld of the powder X-ray diffractometry (PXRD) diagram confirmed the framework topology for COE-1 and COE-2 (chi(2) = 8.0 and 9.9, respectively) and showed that the silicate framework suffers from stacking disorder after interlayer expansion reaction. DIFFaX simulations allowed for the modeling of the stacking disorder, showing that RRO- and HEU-type stacking occurs.