Synthesis and Structure Determination of a New Microporous Zeolite with Large Cavities Connected by Small Pores

A new small-pore germanosilicate zeolite, named as ITQ-49,
has
been synthesized using a new ditetraalkylphosphonium dication as an
organic structure-directing agent, and its structure has been solved
by direct methods applied to the powder X-ray diffraction pattern
of the calcined solid. This new zeolite crystallizes in the space
group Immm with cell parameters a = 19.6007(8) Å, b = 18.3274(7) Å, and c = 16.5335(6) Å. The pore topology of ITQ-49 consists
of large, nonspherical cavities that are connected to each other through
small eight-membered-ring windows, resulting in a unidirectional small-pore
zeolite that has a relatively large adsorption capacity. Also, ITQ-49
contains double four-membered-ring units where Ge is preferentially
located, and fluoride anions are placed inside these units.