Hydrothermally Stable Bimodal Aluminosilicates with Enhanced Acidity by Combination of Zeolite Y Precursors Assembly and the pH-Adjusting Method

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• 作者：Hongtao Liu ; Lei Wang ; Wei Feng ; Li Cao ; Xionghou Gao ; Honghai Liu ; Chunyan Xu
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2013
• 出版时间：March 13, 2013
• 年：2013
• 卷：52
• 期：10
• 页码：3618-3627
• 全文大小：594K
• 年卷期：v.52,no.10(March 13, 2013)
• ISSN：1520-5045

文摘

Through a combination of Y zeolite precursors and the pH-adjusting method, bimodal aluminosilicates (denoted as LFs) with strong acidity and excellent hydrothermal stability were synthesized. The hydrothermal stability of the resulting aluminosilicates was improved greatly by taking advantage of Y zeolite precursors (the retaining ratio of the total surface area was 33% after hydrothermal treatment in 100% water vapor at 800 掳C for 15 h). When the mesostructure was basically formed in the first crystallization, the pH of the reaction system was adjusted from strong acid to neutral, followed by the second hydrothermal crystallization, during which a large amount of Al could be introduced into the mesophases. XRF and Al NMR showed that LFs possessed a high alumina loading (with SiO₂/Al₂O₃ molar ratio of 24.4) and most of the Al was tetrahydrally coordinated. NH₃-TPD results indicated that the total amount of acid sites increased 12.9 times compared with that of ZF (without pH adjustment). The resulting aluminosilicates with simultaneously enhanced acidity and hydrothermal stability showed superior catalytic properties when used in heavy crude oil catalytic cracking. Our achievements have developed a general synthetic route of bimodal aluminosilicates with strong acidity and excellent hydrothermal stability.