Synthesis of amorphous aluminosilicates by grafting: Tuning the building and final structure of the deposit by selecting the appropriate synthesis conditions

摘要: Despite their wide use in the oil refining process, little is known about distribution of aluminium and silicon atoms amorphous aluminosilicates (ASAs). In this paper, we report synthesis both Al/SiO2 Si/Al2O3 ASAs by grafting alkoxides on silica respectively alumina under various conditions. For supports, evidence central roles precursor molecule size reactivity yield deposit structure. Unless hydrolysis alkoxy groups water and/or thermal decomposition occurs, deposition saturated at a monolayer molecules support oxide surface. Additional species can be deposited repeating process provided that hydroxyl top layer are recovered after calcination. 27Al NMR indicates presence five-coordinated materials prepared two successive steps. Transmission electron microscopy (TEM) time-of-flight secondary ion mass spectrometry (ToF-SIMS) confirm controlled selecting appropriate Homogeneous regular favoured anhydrous condition low temperature, while addition during leads to inhomogeneous deposits. case aqueous conditions, nanoparticles form. The accurate knowledge surface structure these opens way better understanding origin Bronsted acidity.