Synthesis and characterization of chiral zeolite ITQ-37 by using achiral organic structure-directing agent

The chiral zeolite germanosilicate ITQ-37 has been prepared by using a new achiral organic structure-directing agent 3′,4′-dihydro-1′H-spiro[isoindoline-2,2′-isoquinolin]-2-ium (denoted as OSDA-1). The crystallization field diagram and the influence of synthetic factors on the synthesis of ITQ-37, such as crystallization temperature, crystallization time, source materials, and water amount have been studied. The as-synthesized samples have been characterized by XRD, ICP, CHN, TG, TEM, DLS, NMR, N2 adsorption and NH3-TPD analysis. The results indicate that the as-synthesized ITQ-37 is a pure phase, and the particle size is of ca. 200 nm. The OSDA-1 cations remain intact in the final product and the framework structure of ITQ-37 maintains up to 500 °C after the removal of OSDA. In addition, Al atoms can be introduced into the framework of germanosilicate ITQ-37 with the Al/(Si + Ge) molar ratio of ca. 1/160–1/80, forming Al-ITQ-37 mainly with weak acid sites.

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► ITQ-37 has been synthesized by using an achiral OSDA.
► The crystallization field diagram of ITQ-37 has been investigated.
► The influence of synthetic factors has been studied in detail.
► The particle size of as-prepared ITQ-37 is ca. 200 nm.
► Al atoms are introduced that leads to mainly weak acid sites.