A Microporous Aluminosilicate with 12‑, 12‑, and 8‑Ring Pores and Isolated 8‑Ring Channels

Synthesis of new
zeolites with controlled pore architectures is
important in the field of catalysis and separation related to chemical
transformation, environmental protection, and energy-saving. Zeolites
containing channels of different sizes in the same framework have
been desirable. We report here the synthesis and structure of a novel
aluminosilicate zeolite (designated as YNU-5), the first zeolite containing
interconnected 12-, 12-, and 8-ring pores, as well as independent
straight 8-ring channels. The synthesis procedure is quite simple
and consists of conventional hydrothermal conditions as well as readily
available starting materials. The framework structure is stable enough
and Si/Al ratio is controllable between 9 and 350. Determination of
the crystal structure is performed by utilizing X-ray diffraction-based
techniques, revealing 9 independent tetrahedrally coordinated atoms.
This robust structure is expected to be industrially valuable and
several unusual combinations of composite building units are of considerable
interest in an academic sense. The new zeolite YNU-5 is promising
catalyst for the production of useful light olefins such as propylene
and butylenes in the dimethyl ether-to-olefin reaction, when the Si/Al
ratio is properly tuned by dealumination through simple acid treatments.