An Aluminosilicate Zeolite Containing Rings of Tetrahedral Atoms with All Odd Numbers from Five to Eleven

Abstract

Herein we report the synthesis, structure solution, and catalytic properties of PST‐31, which has an unprecedented framework topology. This high‐silica (Si/Al=16) zeolite was synthesized using a pyrazolium‐based dication with a tetramethylene linker as an organic structure‐directing agent (OSDA) in hydroxide media. The PST‐31 structure is built from new building layers containing four‐, five‐, six‐, and seven‐membered rings, which are connected by single four‐membered rings in the interlayer region to form a two‐dimensional pore system. Its channels consist of [4.56.6.9.11] and [5.6.7.9.10.11] cavities and are thus delimited by nine‐, ten‐, and eleven‐membered rings. The OSDA cations in as‐synthesized PST‐31 were determined to reside without disorder in the large [42.514.64.72.94] cavities composed of smaller [4.56.6.9.11] and [5.6.7.9.10.11] ones, leading to a symmetry coincidence between the OSDA and the surrounding zeolite cavity. The proton form of PST‐31 was found to be selective for the cracking of n‐hexane to light olefins.

Next generation of nanozymes: A perspective of the challenges to match biological performance

“…In fact, crystals as small as 50 nm can be fully solved by electron diffraction methods. 131 Among the many advantages of TEM over other characterization methods is that it combines spectroscopic analyses with diffraction and imaging; therefore, besides solving the crystal structure with sub-angstrom resolution, it also provides particle size distribution. Conventionally, image analyses have been performed using a parallel beam in this TEM mode; however, complementary to this mode, the electron beam can be controlled to converge into a small probe that scans over the sample, a modality known as scanning transmission electron microscopy (STEM).…”

EMM-25: The Structure of Two-Dimensional 11 × 10 Medium-Pore Borosilicate Zeolite Unraveled Using 3D Electron Diffraction

“…Among the 15 that have been reported, only five have 11-ring pore windows, which are intermediate in size to medium- and large-pore zeolites. Of the five, JU-64 ( JSR ) and PKU-16 ( POS ) are gallogermanate and germanosilicate, respectively, which are unstable to calcination of the organic structure directing agent (OSDA), and only EMM-17, NU-86, and PST-31 are catalytically active aluminosilicates. − PST-31, however, does not contain 11-membered ring channels. NU-86 was the first aluminosilicate zeolite with a proposed 11-ring channel system, and EMM-17 possesses the framework proposed for NU-86 and can be prepared in all-silica or higher-silica compositions.…”