Courieres Thierry Des

Crystallization kinetics of zeolite TON

Crystallization kinetics have been studied for zeolites of structure TON synthesized in the presence of diethanolamine, triethylenetetramine, or methanol. The composition of the solid and liquid fraction and the morphology of gel and crystals have been monitored throughout the syntheses. Under hydrothermal conditions, dissolution of the parent gel and precipitation around it of a secondary gel occur. The experimental conditions (concentration of electrolyte, dilution of the system, nature of the organic agent) modify the texture of the precipitate and the concentrations of silicon and aluminum in solution. Preferential heterogeneous nucleation of the zeolite takes place over the organophilic surface of the secondary gel. In the last phase of the synthesis, the accumulation in the liquid fraction of silicoaluminate species unsuitable for TON growth can bring to the coating of the crystals by an amorphous layer.