Controllable and SDA-free synthesis of sub-micrometer sized zeolite ZSM-5. Part 1: Influence of alkalinity on the structural, particulate and chemical properties of the products

Ren, Nan; Bronić, Josip; Subotić, Boris; Lv, Xin-Chun; Yang, Zhijian; Tang, Yi

doi:10.1016/j.micromeso.2010.10.043

Cited by 77 publications

(55 citation statements)

References 52 publications

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“…[6][7][8][9][10] High alkalinity values tend to increase the solubility of the precursors and form a larger number of smaller crystals. 8,10 For the LTA structure, the synthesis conducted under high alkalinity leads to formation of irregular particles with spherical form. This occurs due to the attack of the hydroxyls, present in greater quantities, on the crystal surface.…”

Section: Introductionmentioning

confidence: 99%

Monitoring of the crystallization of zeolite LTA using Raman and chemometric tools

Chaves

Soares

Cardoso

et al. 2015

Analyst

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LTA zeolite is used both in industry as well as in laboratories, because of its spatial-specific structure which is useful in gas adsorption and in ion exchange separation. At-line reaction monitoring and multivariate analysis of data, such as Principal Component Analysis (PCA), are fundamentals of the Process Analytical Technology (PAT), which consists of the use of analyzers with rapid detection and low sample preparation for analysis during the process stream. In this work, an optimization of zeolite LTA synthesis was performed aiming to obtain nanocrystals and the synthesis was monitored using Raman spectroscopy and PCA. A reaction mixture of 6.2Na2O : Al2O3 : 2SiO2 : 128H2O was used and it was possible to obtain a small particle size and high crystallinity after 72 h of synthesis at 25 °C. The synthesis was monitored at-line, using Raman spectroscopy in both liquid and solid phases. The extension of the reaction could be clearly observed by the PCA scores. As expected, the liquid phase presented changes over time, but the solid phase presented three specific stationary conditions at 0-24 h, 32-56 h and 72-80, related to the beginning of the reaction, the nucleation process, and the crystal formation, respectively. In addition, it was possible to identify the intermediates of the reaction and with the aid of PCA to monitor the reaction close to the real time.

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Section: Introductionmentioning

confidence: 99%

Monitoring of the crystallization of zeolite LTA using Raman and chemometric tools

Chaves

Soares

Cardoso

et al. 2015

Analyst

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“…Obviously, the weak point is that seeded growth approach can often lead to aggregation and intergrown crystals. 41,42 This aggregation seems to be correlated with the amount of seeds used. As zeolites in this work were synthesized with very low amount of seeds (0.1% wt.…”

Section: Discussionmentioning

confidence: 93%

Consequences of secondary zeolite growth on catalytic performance in DMTO studied over DDR and CHA

Yarulina

Dikhtiarenko

Kapteijn

et al. 2017

Catal. Sci. Technol.

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Zeolites with DDR (Sigma-1 and ZSM-58) and CHA (SSZ-13) topology were synthesized by seed assisted and direct hydrothermal synthesis in order to investigate the effects of fast crystal growth on catalytic performance. Application of small amount of seeds (0.1% wt.) significantly reduced synthesis time of all the studied zeolites. XRD and NH 3 -TPD analyses did not reveal any difference in crystallinity and acidity. On the other hand, IR spectroscopy clearly demonstrates the presence of multiple defects, internal silanols (3729 cm -1 ) and silanol nests (3400 cm revealed that, despite smaller crystal sizes, zeolites prepared by secondary growth display shorter lifetimes due to faster coking rates, the latter being a result of silanols promoting hydrogen transfer reactions. This work highlights the importance of zeolite quality for catalytic application and the necessity to optimize current synthetic protocols based on secondary growth.

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“…In the other words, when A < 0.004, fully crystalline product cannot be obtained for t c ≤ 2 h regardless to the content of sodium ions in the reaction mixture [54,55]. Fig.…”

Section: Influence Of Sodium Ions and Gel Ageingmentioning

confidence: 91%

“…Knowing the templating role of sodium ions in the TPA-free synthesis of MFI-type zeolites [13,22,[56][57][58], these findings indicate that the rate-determining factor is concentration of "free" low-molecular weight silicate species, in the short synthesis duration of this seedinduction system Since the generation of these species is mainly caused by hydrolysis of silica precursors which depend on the concentration of "free" OH -ions and thus, on the batch alkalinity, A [54], it is evident that the alkalinity of system, A, determines the rate of crystallization and not the concentration of "free" Na + ions. In the other words, when A < 0.004, fully crystalline product cannot be obtained for t c ≤ 2 h regardless to the content of sodium ions in the reaction mixture [54,55].…”

Section: Influence Of Sodium Ions and Gel Ageingmentioning

confidence: 99%

“…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.…”

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confidence: 99%

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

Ren¹,

Subotić²,

Bronić³

2012

Advances in Crystallization Processes

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Controllable and SDA-free synthesis of sub-micrometer sized zeolite ZSM-5. Part 1: Influence of alkalinity on the structural, particulate and chemical properties of the products

Cited by 77 publications

References 52 publications

Monitoring of the crystallization of zeolite LTA using Raman and chemometric tools

Monitoring of the crystallization of zeolite LTA using Raman and chemometric tools

Consequences of secondary zeolite growth on catalytic performance in DMTO studied over DDR and CHA

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

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