Influence of seeding on FAU–∗BEA interzeolite conversions

High Potential of Interzeolite Conversion Method for Zeolite Synthesis

“…Although the mechanism of crystallization rate enhancement has not been clarified, two explanations have been offered: increased surface area due to the addition of seed crystals results in increased and faster consumption of reagents, or seed crystals promote nucleation through some secondary nucleation mechanism 45) 48) . Figure 3 shows the X-ray diffraction (XRD) patterns of the products obtained at various crystallization times in the absence and presence of BEA seed crystals 38) . Considerable differences were observed in the decomposition/dissolution behavior of the starting FAU type zeolite.…”

“…In the absence of seed crystals, the diffraction peaks corresponding to FAU type zeolite were clearly observed even after hydrothermal treatment for 2 h, but these peaks disappeared completely after 1 d, whereas strong diffraction peaks assigned to BEA type zeolite were clearly observed after hydrothermal treatment for 3 d. On the other hand, in the presence of seed crystals, the diffraction peaks of FAU type zeolite disappeared completely after hydrothermal treatment for 2 h. Surprisingly, the diffraction peaks corresponding to BEA type zeolite was clearly observed after 2 h, and peak intensities hardly changed with longer hydrothermal treatment time, indicating that the crystallization rate of BEA type zeolite was extremely high. Furthermore, the enhancement in the crystallization rate 38) .…”

Hydrothermal conversion of FAU zeolite into LEV zeolite in the presence of non-calcined seed crystals

“…Although the seed crystals employed contained OSDA cations in the zeolitic pores, no additional OSDA was added into the starting gel [17]. Taking into account the fact that LEV and FAU zeolites have similar composite building units (Supplementary Information: Figure S1), these results strongly suggest that it is possible to synthesize LEV zeolite using non-calcined seed crystals without the use of an additional OSDA, if the starting FAU zeolite is decomposed/dissolved into locally ordered aluminosilicate species whose chemical structures are suitable for the crystallization of LEV zeolite.…”

Selective Production of Light Olefins over MSE-type Zeolite Catalyst

“…Hydrothermal conversion of a low density zeolite into a high-density zeolite is possible; for example, they transformed zeolite Y (FAU) transformed into SSZ-13 (CHA) 27) 33) . More recently, rapid crystallization of various zeolites was achieved from an FAU-type zeolite in the presence of a specific OSDA 34) 47) , including the successful transformation of the FAU phase into B E A 34) 36) , R U T 37), 38) , C H A 39) 41) , L E V 42) 44) , MTN 34), 45) , and OFF phases 46) . Synthesis of CHA-type zeolite from LEV-type zeolite was also reported 47) .…”