SSZ-52, a Zeolite with an 18-Layer Aluminosilicate Framework Structure Related to That of the DeNOx Catalyst Cu-SSZ-13

A new
zeolite (SSZ-52, |(C14H28N)6Na6(H2O)18|[Al12Si96O216]), related to the DeNOx catalyst Cu-SSZ-13
(CHA framework type), has been synthesized using an unusual
polycyclic quaternary ammonium cation as the structure-directing agent.
By combining X-ray powder diffraction (XPD), high-resolution transmission
electron microscopy (HRTEM) and molecular modeling techniques, its
porous aluminosilicate framework structure (R3̅m, a = 13.6373(1) Å, c = 44.7311(4) Å), which can be viewed as an 18-layer stacking
sequence of hexagonally arranged (Si,Al)6O6 rings
(6-rings), has been elucidated. The structure has a three-dimensional
8-ring channel system and is a member of the ABC-6 family of zeolites
(those that can be described in terms of 6-ring stacking sequences)
like SSZ-13, but it has cavities that are twice as large. The code
SFW has been assigned to this new framework type. The large cavities
contain pairs of the bulky organic cations. HRTEM and XPD simulations
show that stacking faults do occur, but only at the 5–10% level.
SSZ-52 has considerable potential as a catalyst in the areas of gas
conversion and sequestration.