A green route for the synthesis of nano-sized hierarchical ZSM-5 zeolite with excellent DTO catalytic performance

Insight into Crystallization Features of MOR Zeolite Synthesized via Ice-Templating Method

“…Compared with T-MOR-24 sample, the absorption peaks of IW-MOR-24 and IN-MOR-24 at 3620 cm −1 , 3660 cm −1 and 3750 cm −1 clearly become sharp with the increased intensities (Figure 9). It is indicated that there are more T-OH (T = Si, Al) groups and Si-OH-Al sites, which are closely related to an enhanced acid strength [51][52][53]. Furthermore, the bonding environment of the silicon atoms in the zeolite framework was recorded by the solid-state 29 Si MAS NMR spectrum, and the spectrum resonances centered at around −113, −106 and −100 ppm are ascribed to Si(0Al), Si(1Al) and Si(2Al) structure types, respectively [46].…”

“…The relative decrease in the tetrahedrally coordinated Si(0Al) is confirmed (Q4) (Figure 10 and Table 3). Taking into account of above observations, it is speculated that the ice-templating method changes the chemical environment of silicon atoms in MOR zeolite, resulting in a relative decline in the tetrahedrally coordinated Si-O-Si bond and, correspondingly, an increase in the T-OH (T = Si, Al) groups and Si-OH-Al sites, which is the main reason for their superior acid strength [29,53]. This conclusion is further proven through NH 3 -TPD analysis (Figure 11).…”

Engineering of Yolk/Core–Shell Structured Nanoreactors for Thermal Hydrogenations

“…Recently, a green route with consecutive freezing and vacuum drying process was developed for the preparation of hierarchical ZSM-5. [72] Similarly, a bifunctional Cu/ZnO/γ-Al 2 O 3 nanoreactor was reported for highly selective conversion of syngas to dimethyl ether while a core-shell Cu-MOR@SiO 2 nanoreactor was designed for conversion of syngas and dimethyl ether to ethanol. [73,74] This demonstrates the effectiveness of the synergistic effects achieved by proper modification of the core-shell structure.…”

Facile synthesis of nanosized mordenite and beta zeolites with improved catalytic performance: non-surfactant diquaternary ammonium compounds as structure-directing agents

“…12,13 Compared to top-down approaches, bottom-up methods provide more flexibility in the preparation of nanocrystalline zeolites. 14 Without being exhaustive, approaches may include a change in the order of mixing the reagents, 15,16 replacing traditional heating by microwave irradiation, 17 the use of ultradense gels crystallized by steam treatment 18 and decoupling nucleation from crystal growth via a temperature-staged approach. 19,20 Confined space synthesis was also employed to prepare nanosized zeolites, involving crystallization of the zeolite inside a mesoporous matrix.…”