Investigation of Extra-Large Pore Zeolite Synthesis by a High-Throughput Approach

Abstract

Seven isoindoline-based organic structure directing agents (OSDAs) with increasing sizes have been prepared and each applied in a high throughput (HT) design of 33 × 5 experiments by varying the synthesis parameters such as Si/Ge, Al(B)/(Si+Ge), F–/(Si+Ge), and H2O/(Si+Ge). Among the 945 experiments, 395 lead to crystalline zeolite products, corresponding to eight zeolites, i.e., Beta (3D 12 × 12 × 12 ring), ITQ-7 (3D 12 × 12 × 12 ring), ITQ-17 (3D 12 × 12 × 12 ring), ITQ-15 (2D 14 × 12 ring), ITQ-21 (3D 12 × 12 × 12 ring), ITQ-37(3D 30 ring), ITQ-43 (3D 28 × 12 × 12 ring), and ITQ-44 (3D 18 × 12 × 12 ring). Most of the crystalline phases obtained (85.8%, 339 of 395) are Beta, ITQ-7, ITQ-17, and intergrowths of ITQ-7 and ITQ-17, which have been named as “Default Structures” here. It has been found that concentrated gels and high Ge/Si ratio favor the formation of low framework density structures. When the OSDAs are relatively small, only “Default Structures” can be obtained, while if the size of OSDA increases above a certain dimension, extra-large pore zeolites such as ITQ-15, ITQ-37, ITQ-44, and ITQ-43 start to appear. The mesoporous chiral zeolite ITQ-37 has been successfully synthesized here with a much less costly achiral template than the one used originally. It has also been found that there is an intergrowth of ITQ-7 and ITQ-17 due to their closely correlated structures.