Comparison of dealumination of zeolites beta, mordenite and ZSM-5 by treatment with acid under microwave irradiation

Influence of the nitric acid treatment on Al removal, framework composition and acidity of BEA zeolite investigated by XRD, FTIR and NMR

“…Thus, the removal of framework Al atoms leads to change of acidity and catalytic activity of zeolites. So, the zeolite dealumination has therefore been a matter of a lot of work [13][14][15][16][17][18][19][20][21]. There are several factors that influence the zeolite dealumination process such as zeolite structure, synthesis conditions and dealumination method used.…”

“…Different zeolites such as beta (BEA), mordenite (MOR) and ZSM-5 (MFI) are known to exhibit different behaviour upon dealumination [13][14][15]. It was shown [14] that the extent of dealumination decreased in the same order as the number of T-sites in fourrings: beta > mordenite > ZSM-5.…”

Effect of microwaves, ultrasounds and interlayer anion on the hydrocalumites synthesis

“…The layer construction of hydrocalumite probably has lower rate of formation than katoite, a nonlayered compound. It is well known that microwaves can accelerate organic reactions (oxidation, polymerization, reduction) [29], and inorganic synthesis (zeolites, clays) [20][21][22][23][24], among others.…”

“…In recent years, the use of microwaves for the synthesis or modification of materials is becoming an important tool to decrease the synthesis time, with the subsequent energy saving, and to modify the sample properties, which can be of interest for catalysis [20][21][22][23][24]. Additionally, ultrasounds is another interesting technique to improve the synthesis of materials since, when used for the mixing of reagents, allows obtaining materials with more homogeneous composition [23][24][25].…”

Studies of Modification of Zeolite by Tandem Acid-Base Treatments and its Adsorptions Performance Towards Thorium

“…Small ions and two common methods, i.e., thermal treatment (commonly by steaming) [4] or acid leaching [5]. Dealumination changes the Si/Al ratio in zeolite, hence affecting the surface and acidic properties of zeolite [6]. The desilication process, where it is the silicon atoms which are removed, follows the same pattern as dealumination such as type of lattice defects and mesopore formation.…”