A seed surface crystallization approach for rapid synthesis of submicron ZSM-5 zeolite with controllable crystal size and morphology

Crystallization of Sub-Micrometer Sized ZSM-5 Zeolites in SDA-Free Systems

“…Compared with the phenomenological description, the quantitative explanation of the crystallization step makes the further control of the process much easier and convenient. On the basis of above presented data, it can be assumed that the crystallization process is a typical seed-induced one which can be mathematically expressed by a cubic function [50,59,60], i.e.…”

“…Taking into consideration that the formation of nuclei in the crystallizing system is depressed by both by the absence of SDA [50] and presence of seed crystals [50,59,60] it is reliable to assume that the number of growing crystals, N t , is constant and equal to the number, N 0 , of the added seed crystals. Then, the change of the mass, m t , of the crystallized zeolite ZSM-5 with the crystallization time t, can be expressed as,…”

“…(2) using crystal growth rate of 0.15 μm/h c. determined from the corresponding SEM images (Adopted from Ref. [50] with permission of Publisher) Based on the analysis of experimental data in both phenomenological and mathematical way, the crystallization mechanism and the corresponding critical processes occurring during crystallization are depicted in Fig. 24.…”

“…Most of the mentioned problems can, however, be overcome by addition of small amount of seed crystals (ZSM-5, silicalite-1) in the TPA + -free reaction mixture [6,27,35,38,40,45,50]. Seed induction synthesis is a well developed strategy which could not only shorten the duration of synthesis, but also control the product properties [51]; addition of seed crystals results in the formation of zeolite ZSM-5 with high degree of crystallinity and a narrow size distribution at short synthesis times [38,40].…”

“…Taking into consideration the background of ZSM-5 synthesis conditions, and accompanying this with the basic knowledge of seed induced synthesis, we have developed a seed surface crystallization (SSC) approach, in which the sub-micrometer sized ZSM-5 zeolites can be obtained in a controllable manner [50,54,55]. More importantly, the growth of crystalline end products is achieved in a heterogeneous, SDA-free crystallization system, which is good basis for their further industrial-scale production and use in various applications.…”