Hydrothermal synthesis of mesostructured aluminosilicate nanoparticles assisted by binary surfactants and finely controlled assembly process

Mesostructured aluminosilicate nanoparticles with narrow grain size distribution have been hydrothermally prepared for the first time with assistance of binary surfactants and separate hydrolysis and assembly of inorganic precursors. Compared to the sample assembled at room temperature, condensation degree and aluminum stability were greatly improved using hydrothermal treatment. The formation of nanoparticles consists of two steps, that is, the hydrolysis of silica precursor via catalysis by an acidic aluminum salt, followed by facile assembly into mesostructured nanocomposites with cationic micelles by addition of condensation catalyst. Simultaneously, nonionic polyethylene glycol (PEG-4000) present in this process would surround the formed nanoparticles through hydrogen-bonding interactions, thereby tailoring the grain size distribution and preventing aggregation and growth of inter-nanoparticles during the hydrothermal treatment process. The microstructure and chemical compositions of these products were thoroughly characterized by XRD, SEM, TEM, N₂ sorption and ²⁷Al MAS NMR techniques.