Synthesis, Structure Solution, Characterization, and Catalytic Properties of TNU-10:  A High-Silica Zeolite with the STI Topology

Abstract

A high-silica zeolite (Si/Al = 7.1) with the STI framework topology, denoted TNU-10, has been synthesized in the presence of 1,4-bis(N-methylpyrrolidinium)butane and Na(+) cations as structure-directing agents, and its structure in the proton form has been refined against laboratory powder X-ray data in space group Fmmm (a = 13.533(1) A, b = 17.925(2) A, c = 17.651(2) A). The space group symmetry is supported by electron diffraction and energy minimization studies. The as-made and proton form of TNU-10 are extensively characterized by elemental and thermal analyses, scanning electron microscopy, N(2) adsorption, multinuclear solid-state NMR, IR, and temperature-programmed desorption of ammonia, and the location of the organic structure-directing agent in the channel system is determined by molecular modeling. The catalytic properties of H-TNU-10 and Co-TNU-10 are evaluated for the skeletal isomerization of 1-butene to isobutene and the selective reduction of NO with methane, respectively. When compared to H-ferrierite, a low selectivity to isobutene is observed for H-TNU-10. However, it is found that Co-TNU-10 exhibits a maximum NO conversion of 93% at 823 K under conditions of high concentrations of methane (16,000 ppm) and water vapor (10%) and in the presence of 2.6% O(2), which is considerable higher than even the value (74%) obtained from Co-ferrierite, known as the best catalyst for this reaction, under the identical conditions.

Synthesis and Formation Mechanism of Textured MOF-5

“…For example, reasonably good HRTEM images have been obtained from zeolites, C 60 /trimethylbenzene composite, and MOFs. [32][33][34][35] Using a very low dose of electron beam, some HRTEM images of fragments of MOF-5 nanoplates were obtained as shown in Figures 5e and 5f. Although some structural degradation is visible in the HRTEM images, weak crystalline fringes are observed along the profile and long axis of the nanoplates.…”

Study of propane oxidation on Cu-zeolite catalysts by in-situ EPR and IR spectroscopies

“…Zeolite TNU-9 was synthesized according to the procedure described previously [21,22], using 1,4-bis-(N-methylpryrrolidinium)-butane and Na + cations as structure directing agents (SDAs). ITQ-2 was prepared by swelling the MCM-22 precursor with a water solution of hexadecyltrimethylammonium bromide and tetrapropylammonium hydroxide following the method depicted in previous publications [23,24].…”

Structural Chemistry of Zeolites

“…This is very encouraging, as ever more complex structures are prepared, and suggests that an inability to grow single crystals should not limit our discovery of their intricate architectures. Both TNU-9 and IM-5 crystallize in the presence of the same organic SDA, bis-N-methylpyrrolidiniumbutane, which has also been shown to favor the crystallization of several other zeolites depending on solution pH, Si/Al ratio, additional cations, and so on [29]. This is a clear indication that the detailed composition of the hydrothermal reaction mixture plays a crucial role in supplying species for the growth of these complex solids.…”

“…Zones has investigated the effect of variation of Si/Al and Si/B ratios in the gel as additional parameters in the syntheses with new potential SDAs [26], and Corma (and the Mulhouse and Stockholm groups) found that the inclusion of germanium had a strong structure-directing influence, because of its propensity to favor the formation of D4Rs [11, 27,28] . Furthermore, the addition of inorganic cations and variation of alkalinity (OH − /T) have been shown to have an important influence on the zeolite structure to form [29].…”