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Abstract

Nanoslabs (2): Small square domains of lighter contrast observed with TEM on NaCl particles are attributed to tetrapropylammonium‐silicalite‐1 nanoslabs carefully extracted from a nanoslab suspension (see TEM image).

Hierarchical Nanomanufacturing: From Shaped Zeolite Nanoparticles to High‐Performance Separation Membranes

“…[176] Conclusive and noncontradictory evidence of the latter mechanism is lacking. [168,[177][178][179][180] On the other hand, an undisputed commonality among the former four is the consistent detection of precursor nanoparticles (approximately 3-5 nm in size) in fresh and aged TPA-silica precursor solutions bearing no evidence of silicalite-1 structure. [169][170][171][172]181] While the focus of this Review is mainly upon silicalite-1 obtained from clear sols, it is important to recognize that silicalite-1 [182] and other zeolites [173,174,183] can result from nucleation in and transformation of amorphous gels, reminiscent of the non-zeolitic systems discussed previously.…”

Transmission electron microscopy in formation and growth of ordered mesoporous materials

“…In MCM-41 type materials the pore wall thickness is about 1 nm, and therefore it would be very difficult to accommodate such highly structured bricks into a highly condensed crystalline wall. It is still under discussion, based on observations from TEM images and ED patterns, whether those "nanoslabs" are zeolite building blocks or not [27][28][29]. Beam sensitivity and misalignments of zeolite "nanoslabs" have been used in the literature as an explanation for the absence of Bragg scattering in the ED patterns [26].…”

Formation of Al-rich nanocrystalline ZSM-5 via chloride-mediated, abrupt, atypical amorphous-to-crystalline transformation

“…NaCl is effective in salting out polysilicates 43,44 together with TPA. 45 The amorphous solids at time 1.5 h also contained tetrahedrally coordinated Al 3+ , indicating that they had the full complement of chemical components needed to evolve into the final ZSM-5 structure. Due to the low degree of connectivity, the structures at 1.5 h were open and polar with a high density of SiO À M + units (where M + is Na + or TPA + ).…”