A facile strategy of preparing nanosized NaY zeolite by stimulating negative crystals to accelerate the formation of D6R units

Ultrasonic-pretreated hydrothermal synthesis of less dense zeolite CHA from the transformation of zeolite T

“…It seems that MER phase is easy to be formed in the KOH-rich condition and GIS phase is inclined to the produced in the NaOH-rich condition from the same original materials. Literature [64] reported that the formation of D6R units could be promoted by Na + , and the result in this paper somewhat reinforced this statement. The mixed-crystal phenomenon in NaOH-treated solution is weaker than that in KOH-treated solution.…”

The Current Understanding of Mechanistic Pathways in Zeolite Crystallization

“…One subject that receives relatively less attention is the effect of anions, which are introduced to zeolite growth mixtures as counterions to the organic or inorganic SDAs and are often assumed to have a negligible effect; however, it is known that their concentration can influence crystallization kinetics, framework stability, and crystal size . Shen and co-workers examined the effect of different sodium halides on zeolite FAU precursors. Figure compares TEM images of amorphous gels that were prepared in the absence of halides (Figure a) to those in the presence of NaCl (Figure b) and NaBr (Figure c).…”

“…White arrows in the high-resolution image in (a) indicate the higher density of bright spots located near the gel periphery. Adapted with permission from ref . Copyright 2022 Elsevier.…”

Hierarchical submicrosized Y zeolites prepared by sequential desilication–dealumination post-synthesis modification and their catalytic performance in vacuum gas oil hydrocracking

“…Furthermore, the external surface area and the number of external active sites of zeolites increase as the particle size decreases, which thereby benefit catalytic activity in reactions involving large molecules. 3 Reduction in particle size in zeolites has been reported by different investigations, [4][5][6] where the effect of varying the synthesis conditions such as gel composition, alkalinity, Si/Al ratio, stirring rate, seeding, time and crystallization temperature is used to control the crystal size. Among these factors, the Si/Al ratio, time and crystallization temperature are the most important for controlling crystal size.…”