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

Abstract

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 °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 SiO 2 /Al 2 O 3 molar ratio of 24.4) and most of the Al was tetrahydrally coordinated. NH 3 -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.

High-Temperature Synthesis of Ordered Mesoporous Aluminosilicates from ZSM-5 Nanoseeds with Improved Acidic Properties

“…On the other hand, it should be noted that at the same initial Si/Al ratio of 30, the acid site density of SAZ-30 is higher than that of Al-SBA-15. This result further supports the work of Han et al [ 6 ] and others [ 7 , 8 , 9 , 18 ] who found that the introduction of zeolite building units in the mesopore walls induced an improved acidity of SBA-15 analogs.…”

Novel non-hydrolytic templated sol–gel synthesis of mesoporous aluminosilicates and their use as aminolysis catalysts

“…[46][47][48] Solid state NMR spectroscopy (Table 2) was employed for indepth characterization of the aluminosilicate xerogel matrix. 13 C CPMAS NMR spectrum of non-templated sample (SiAl1) displayed resonances of residual organic groups (Fig. 5S †).…”

Hydrothermally stable macro-meso-microporous materials: synthesis and application in heavy oil cracking

“…[6][7][8] For example, the authors of the present investigation have prepared hydrothermally stable mesophase by assembling Beta and Y precursors with P123. [9][10][11][12][13] Unfortunately, macropores are still absent in these materials, and so forth, which limit their practical application. Therefore, one effective solution to this problem is to develop a novel preparation strategy for the immobilization of macropores into the meso-microporous materials.…”

“…Moreover, the authors of the present investigation have prepared mesoporous aluminosilicates (denoted as LFs) by combination of precursors assembly and pH-adjusting method and the yield of light fraction oil of LF-3 is 67.19%. 9 It is generally accepted that the activity of catalysts also depends on the acidity. In Cat-2, 5% MSA replaces 5% kaolin in Cat-1.…”