Crystal-Seeds-Based Strategy for the Synthesis of Hydrothermally Stable Mesoporous Aluminosilicates with a Largely Decreased H₂O Amount

Abstract

Recent advances in the synthesis of hydrothermally stable mesoporous aluminosilicates (MAs) by assembling precursors shed light on their applications in residue fluid catalytic cracking. Reducing the n(H2O)/n(SiO2) ratio and thus reducing waste discharge is the key for practical applications of MAs. In this study, the synthesis of hydrothermally stable MAs with a decreased n(H2O)/n(SiO2) ratio has been developed based on seed-assisted crystallization. Crystal seeds were partly dissolved to microcrystallites on which a large amount of zeolite precursors are assembled and crystallized. As a direct result of the assembly priority of crystal seeds, the concentration and viscosity of the liquid phase in the synthesis system will be decreased greatly. Afterward, the remaining precursors with proper concentration and viscosity can be assembled with the surfactant micelles. Therefore, the H2O amount could be largely decreased by the introduction of crystal seeds.

Urea as Efficient Additive toward Decreasing Water Amount in Synthesis of Hydrothermally Stable Mesoporous Aluminosilicates

“…Zeolite Y precursors were prepared according to the literature . The mixtures of water glass, aluminum sulfate, and NaOH solution with the identical molar ratio of Na 2 O:Al 2 O 3 :SiO 2 :H 2 O at 16:1:15:320 were prepared.…”

Synthesis and characteristics of SBA-15 with thick pore wall and high hydrothermal stability

“…These approaches contain the past-treatment with organosilane [9,10], pH adjusting [11], increasing hydrothermal treatment temperature [12,13], removing surface Si-OH groups by silylation and F-ions [14,15], addition of crystal seed precursors [16,17], doping heteroatoms [18,19], and addition of inorganic salts [20,21]. These methods have played an important role in improving hydrothermal stability of mesoporous materials.…”

Spherical V-Fe-MCM-48: The Synthesis, Characterization and Hydrothermal Stability

“…Furthermore, the relatively poor hydrothermal stability also limits the application of mesoporous silicate materials in the liquid-phase reactions [ 23 ]. Some approaches to improve the hydrothermal stability have been reported, such as incorporating heteroatoms [ 24 , 25 , 26 ], pH adjusting [ 27 ], addition of crystal seed precursors, inorganic salts, or PVA powder [ 28 , 29 , 30 , 31 ].…”