Interlayer Expansion of the Hydrous Layer Silicate RUB-36 to a Functionalized, Microporous Framework Silicate: Crystal Structure Analysis and Physical and Chemical Characterization

The hydrous layer silicate RUB-36, (C6H16N)(4) [H4Si36O76], has been used for an interlayer expansion reaction with dichlorodimethylsilane to interconnect neighboring ferrierite-type layers to a three-dimensional framework silicate. The linker group (-O-Si(CH3)(2)-O-) still has the two methyl groups in the as-synthesized form (material name COE-3 [Si20O38(CH3)(4)] for the silicate framework) rendering hydrophobic properties. The interlayer expanded zeolite, IEZ, is thermally stable and can be calcined at 550 degrees C to yield a hydrophilic material COE-4 [Si20O38(OH)(4)]. Si-29 solid state MAS NMR experiments confirm the insertion of the linker group and the methyl and hydroxyl substitution in the as-made and calcined form, respectively. The BET surface area is 238 m(2)/g for COE-3 and 350 m(2)/g for COE-4. COE-3 and COE-4 crystallize in space group Pm with a = 12.2503(3) angstrom, b = 13.9752(2) angstrom, c = 7.3850(1) angstrom, and beta = 107.33(1)degrees and a = 12.16985(4) angstrom, b = 13.95066(3) angstrom, c = 7.37058(2) angstrom, and beta = 107.30(1)degrees, respectively. Rietveld crystal structure refinement of the PXRD pattern of COE-3 and COE-4 reveal the expanded, two-dimensional 10-ring pore system including the linker group as homogeneous structural property of the materials.