Nature and Structure of High Silica Zeolites Synthesized in Presence of (Poly) Alkyl Mono- and Diamines

One-step synthesis of hierarchical pentasil zeolite microspheres using diamine with linear carbon chain as single template

“…Furthermore, different morphology pentasil zeolites could be synthesized by using various diamines as templates, which may be due to the different molar compositions of the synthetic mixtures, and the different nature and concentration of the starting materials. [22][23][24][25][26] However, the size of zeolite microspheres did not drastically change with varying diamine chain length. This relatively large aggregate size is a positive fact that favors easy recovery in their preparation and application.…”

Zeolite Synthesis Using Flexible Diquaternary Alkylammonium Ions (CnH2n+1)2HN+(CH2)5N+H(CnH2n+1)2withn= 1−5 as Structure-Directing Agents

“…While ZSM-11 was originally synthesized using tetrabutylammonium (TBA) ion as the organic SDA, a subsequent transmission electron microscopy (TEM) study showed that not only was the material prepared with TBA actually ZSM-11/ZSM-5 intergrowth, but also the synthesis of pure-phase ZSM-11 was quite a difficult task . The fact that Pe 4 -diquat-5 and sec -Bu 4 -diquat-5 can give this intergrowth is somehow unexpected, because tetraalkylammonium cations with pentyl, hexyl, or heptyl groups bulkier than butyl are reported to exclusively crystallize ZSM-5 under the same synthesis conditions . However, we note that the presence of Bu 4 -diquat-5, Pe 4 -diquat-5, or sec -Bu 4 -diquat-5 in the synthesis mixture is prerequisite for the crystallization of ZSM-11/ZSM-5 intergrowths even under conditions where the gel composition (SiO 2 /Al 2 O 3 = 120 and NaOH/SiO 2 = 0.33) is optimized, revealing some degree of their product specificity for the MEL structure.…”

Preparation of Zeolite ZSM-5 Membranes by In-Situ Crystallization on Porous .alpha.-Al2O3

“…The axis.0 Judged from the morphology of the top layer. d Crystallization presence of sodium ions has multifaceted effects on crystal size and morphology (Mostowicz and Berak, 1985;Nastro et al, 1985;Gabelica et al, 1985). For syntheses utilizing TPA+, the presence of Na+ is known to decrease the nucleation and crystallization rates, but in the experiments listed in Table 3 the simultaneous change of Na+ and alkalinity does not permit clear-cut comparisons with the known trends. "…”