Hydrolysis of aluminium alkoxides and bayerite conversion

Abstract A study of hydrolysis of aluminium alkoxides as a function of water temperature, and structural transformation of the resultant hydroxides was conducted. Hot water hydrolysis of aluminium alkoxides produces boehmite, whereas cold water hydrolysis results in formation of amorphous monohydroxide. This amorphous phase contains OR groups whose removal by water during aging causes the material to convert to bayerite or boehmite. Bayerite conversion takes place below 80 °C by a dissolution‐recrystallisation process in which the gradual liberation of OR groups by water appears to play an important role. Boehmite conversion takes place above 80 °C where vigorous liberation of OR groups occurs and the slow stoichiometric bayerite conversion diminishes. Neither conversion takes place in pure alcohol.