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.

The Complex Crystal Structure and Abundant Local Defects of Zeolite EMM‐17 Unraveled by Combined Electron Crystallography and Microscopy

“…Hence, the structure of EMM-17 is characterized by ac omplex 3D channel system designated as 10(12) 10(12) 11-rings.I ti s worth noting that there are very few zeolites having 11membered rings,i ncluding gallogermanate JU-64, germanosilicate PKU-16, borosilicate EMM-25, aluminosilicate PST-31, and aluminosilicate NU-86. [28,[30][31][32][33] JU-64 and PKU-16 are unstable upon the removal of OSDAs.T oo ur knowledge, EMM-17 is the only 11-ring zeolite that can be synthesized in both aluminosilicate and silicate forms.I mportantly,i ts structure is highly stable under thermal and hydrothermal conditions (Figure S3), which means that its unique 11-ring channels are fully accessible and useful for separation and catalysis.…”

The Complex Crystal Structure and Abundant Local Defects of Zeolite EMM‐17 Unraveled by Combined Electron Crystallography and Microscopy

“…Hence, the structure of EMM‐17 is characterized by a complex 3D channel system designated as 10(12)×10(12)×11‐rings. It is worth noting that there are very few zeolites having 11‐membered rings, including gallogermanate JU‐64, germanosilicate PKU‐16, borosilicate EMM‐25, aluminosilicate PST‐31, and aluminosilicate NU‐86 [28, 30–33] . JU‐64 and PKU‐16 are unstable upon the removal of OSDAs.…”

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

“…[11] Rietveld refinement was also carried out using synchrotron PXRD data ( Figure S7 and Tables S3-S6). [12] Thef inal refined unit cell parameters determined were a = 13.8222(7) , b = 14.3797 5 (Figure 2a). These modified double-4 ring (d4r)u nits are connected one another by sharing the T-atoms in stellated points (in green), with glide arrangement, to form the PST-31 building chain (Figure 2b).…”

“…We next carried out PXRD and Rietveld analyses on the dehydrated, as-synthesized PST-31 to determine the OSDAl ocation (Figure S12 and Tables S8-S11). [12] A piece of the positive electron density remaining after initial scaling, [16] corresponding to a1 4DMP-C 4 2+ molecule,w as determined to be located within the large [4 2 .5 14 .6 4 .7 2 .9 4 ]c avity consisting of two [4.5 6 .6.9.11] and two [5.6.7.9.10.11] ones (Figure 4a). We also note that this OSDAspans the 10-and 11-rings,b ut not the 9-rings ( Figure S13).…”