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, N ₂ adsorption and NH ₃-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.