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

Abstract

Cs–pollucite can be a potential solid base catalyst due to the presence of (Si-O-Al)−Cs+ basic sites. However, it severely suffers from molecular diffusion and pore accessibility problems due to its small micropore opening. Herein, we report the use of new organosilane, viz. dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (TPOAC), as a promising pore-expanding agent to develop the hierarchical structure in nanosized Cs–pollucite. In respect to this, four different amounts of TPOAC were added during the synthesis of hierarchical Cs–pollucite (CP-x, x = 0, 0.3, 1.0, or 2.0, where x is the molar ratio of TPOAC) in order to investigate the effects of TPOAC in the crystallization process of Cs–pollucite. The results show that an addition of TPOAC altered the physico-chemical and morphological properties of hierarchical Cs–pollucite, such as the crystallinity, crystallite size, pore size distribution, surface areas, pore volume, and surface basicity. The prepared solids were also tested in Claisen–Schmidt condensation of benzaldehyde and acetophenone, where 82.2% of the conversion and 100% selectivity to chalcone were achieved by the CP-2.0 catalyst using non-microwave instant heating (200 °C, 100 min). The hierarchical CP-2.0 nanocatalyst also showed better catalytic performance than other homogenous and heterogeneous catalysts and displayed a high catalyst reusability with no significant deterioration in the catalytic performance even after five consecutive reaction runs.

Direct evidence of time-dependent crystallization evolution of SAPO-34 and SAPO-20 zeolites directed by trimethylbenzylammonium hydroxide for microwave-assisted ethanolysis of furfuryl alcohol

“…7b). 50 As a result, high specific BET surface area is shown by SAPO-34 (393 m 2 g −1 ) as compared to SAPO-20 (29 m 2 g −1 ) (Table 2). Furthermore, the Non-local Density Functional Theory (NLDFT) method also reveals that SAPO-34 has a larger average pore size (3.26 nm) due to its primary micro- and textural mesoporosities.…”

Chalcone: A Promising Bioactive Scaffold in Medicinal Chemistry

“…Later, to increase the yield, different catalysts were also tried [ 58 , 59 ]. For example, materials such as chitosan [ 60 ], Al–Mg hydrotalcite [ 61 ], and Cs-pollucite nanozeolite modified with organosilane [ 62 ] have been used for the reaction. The acid-based catalyst, i.e., BF 3 -Et 2 O, has many advantages over others, with the yield of the chalcone increasing drastically, which is also helpful for the ease of production [ 2 ].…”

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

“…On the other hand, the total surface area of the samples was measured with the N 2 adsorption isotherm analysis. Note that the total surface area determined was actually contributed only by the external surfaces because the size of N 2 molecules is too large to probe the micropores of the K-MER zeolite [27,37]. The results indicated that the external surface area had positive correlation with the crystallite size of K-MER zeolite.…”