Organic‐Free Synthesis of Zeolite Y with High Si/Al Ratios: Combined Strategy of In Situ Hydroxyl Radical Assistance and Post‐Synthesis Treatment
Jianyu Wang, Pusheng Liu, Mercedes Boronat, Pau Ferri, Zhaoguo Xu, Peng Liu, Baojian Shen, Zhendong Wang, Jihong Yu
Abstract
Abstract Zeolite Y, with a high SiO 2 /Al 2 O 3 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.