Micro- and macroscopic observations of the nucleation process and crystal growth of nanosized Cs-pollucite in an organotemplate-free hydrosol

Abstract

Nucleation and crystal growth of a nanosized cesium pollucite zeolite from an organotemplate-free hydrosol under mild conditions (low pressure and temperature) are followed and reported.

Composition, Thermal Expansion and Phase Transitions in Framework Silicates: Revisitation and Review of Natural and Synthetic Analogues of Nepheline-, Feldspar- and Leucite-Mineral Groups

“…Indeed, physical and chemical properties have led to very widespread industrial and environmental applications for feldspars and feldspathoid minerals and bulk rocks to semiconductors, glass making/ceramics, building and construction, and functional fillers in paints and composites [1]. Specific examples include nepheline and leucite in glass ceramics [2][3][4]; feldspar and nepheline in pottery, porcelain, and sanitary ware [5][6][7]; ionic and thermal conductivity [8][9][10]; catalysis and molecular sieving [11][12][13]; radioactive waste disposal [14][15][16]; dental ceramics [17][18][19]; and geophysical surveying [20][21][22].…”

Effects of Synthesis Parameters on Crystallization Behavior of K-MER Zeolite and Its Morphological Properties on Catalytic Cyanoethylation Reaction

“…Further increasing the K 2 O content (x = 7.0: W-9) led to the formation of K-MER zeolite with only pure prismatic-shape crystals (Figure 6c). As seen, the average size of prismatic shape crystals also reduced from 125 × 167 nm 2 to 114 × 160 nm 2 when the K 2 O content increased due to the enhancement of the solubility of aluminosilicate species as a result of higher alkalinity in the hydrogel solution [32].…”

Hierarchical Cs–Pollucite Nanozeolite Modified with Novel Organosilane as an Excellent Solid Base Catalyst for Claisen–Schmidt Condensation of Benzaldehyde and Acetophenone

“…In general, all samples displayed almost similar IR spectrum patterns as that of the theoretical pollucite solid, indicating that all samples retained their framework identity as also previously confirmed by the XRD study ( Figure 5). The IR bands at 1014 and 1035 cm −1 are assigned to the internal vibrations of Si-O-T (T = Si, Al) asymmetric stretching modes while the signals resonated at 774, 720, and 631 cm −1 are the characteristics of distorted eight-membered ring sub-units present in the pollucite framework [18]. Furthermore, the IR band at 441 cm −1 is due to the bending vibration of TO 4 .…”

“…In order to confirm that TPOAC was chemically bound to the Cs-pollucite framework, as-synthesized CP-0 and CP-2.0 were selected and characterized with 29 Si MAS + DEC nmR spectroscopy. For CP-0, a broad signal is shown in the range of −72.9 to −104.1 ppm, where this band is due to the Q 1 : Si(OAl) 4 and Q 2 : Si(OSi)(OAl) 3 ) species originating from the Cs-pollucite framework (Figure 2a) [18]. On the other hand, CP-2.0 also exhibits the same nmR band at this region and a weak additional broad peak is also observed from −55 to −75 ppm, where this peak is contributed by the T n species (T n = RSi(OH) 3−n , n = 2 and 3) of TPOAC ( Figure 2b) [31].…”

“…In order to overcome the diffusion limitation of bulky molecules in Cs-pollucite, a viable approach has recently been proposed by downsizing the crystallite size to the nanometer range (<100 nm), with the aim of enhancing the external surface area of the zeolite [14][15][16]. As a result, the number of (Al-O-Si) − Cs + basic sites accessible for reactants is increased, giving considerably good catalytic activity in Perkin condensation of benzaldehyde [17] and cyanoethylation of amine [18]. However, the surface area of nanosized Cs-pollucite is still very low (<40 m 2 g −1 ).…”