Organic‐Free Synthesis of Zeolite Y with High Si/Al Ratios: Combined Strategy of In Situ Hydroxyl Radical Assistance and Post‐Synthesis Treatment

Zeolite Y, with a high SiO2/Al2O3 ratio (SAR), plays an important role in fluidized catalytic cracking processes. However, in situ synthesis of zeolite Y with high SARs remains a challenge because of kinetic limitations. Here, zeolite Y with an SAR of 6.35 is synthesized by a hydroxyl radical assist...

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Published in:Angewandte Chemie International Edition 2020-09, Vol.59 (39), p.17225-17228
Main Authors: Wang, Jianyu, Liu, Pusheng, Boronat, Mercedes, Ferri, Pau, Xu, Zhaoguo, Liu, Peng, Shen, Baojian, Wang, Zhendong, Yu, Jihong
Format: Article
Language:English
Subjects:
Aluminum oxide
Catalytic cracking
Citric acid
cracking
Crystallization
Cumene
density-functional calculations
Fluidizing
Free radicals
heterogeneous catalysis
Hydroxyl radicals
radicals
Silicon dioxide
Yttrium
Zeolites
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Summary:Zeolite Y, with a high SiO2/Al2O3 ratio (SAR), plays an important role in fluidized catalytic cracking processes. However, in situ synthesis of zeolite Y with high SARs remains a challenge because of kinetic limitations. Here, zeolite Y with an SAR of 6.35 is synthesized by a hydroxyl radical assisted route. Density‐functional theory (DFT) calculations suggest that hydroxyl radicals preferentially enhanced the formation of Si‐O‐Si bonds, thus leading to an increased SAR. To further increase the SAR, a dealumination process was carried out using citric acid, with a subsequent second‐step hydrothermal crystallization, giving an SAR of up to 7.5 while maintaining good crystallinity and high product yield. The resultant zeolite Y shows good performance in cumene cracking. Introduced here is a new strategy for synthesizing high SAR zeolite Y, which is widely used in commercial applications. Zeolite Y with a SiO2/Al2O3 ratio (SAR) of 6.35 is hydrothermally synthesized by using a hydroxyl radical assisted route. To further increase the SAR, a dealumination process was performed with citric acid and a subsequent second‐step hydrothermal crystallization, giving an SAR of up to 7.5 while maintaining good crystallinity.
ISSN:1433-7851
1521-3773
DOI:10.1002/anie.202005715