THE SYNTHESIS OF FERRIERITE, ZSM-5, AND THETA-1 IN THE PRESENCE OF DIETHANOLAMINE - EXPERIMENTAL

The synthesis of zeolites from gels containing silica, alumina, potassium and/or sodium hydroxide or chloride, diethanolamine, and water was studied. Zeolites Theta-1, ZSM-5, ferrierite, and mordenite, and the dense phase cristobalite, were produced by varying the SiO2/Al2O3 ratio, the alkalinity and the alkali metal cation. The effect of varying the SiO2/Al2O3 ratio was found to be of great importance. The ranges of SiO2/Al2O3 ratios over which each zeolite is formed have been established, and discrete upper and lower limits were found to exist in the cases of ZSM-5, Theta-1, and ferrierite. The formation of these materials was followed under a variety of conditions using X-ray diffraction, thermal analysis, MAS n.m.r. and AAS. The kinetics of formation of these zeolites were investigated, as were the compositions and characteristics of the solid phases collected during the syntheses. The location and charge of the diethanolamine present within the solid materials were found to be significant. Diethanolamine is considered to have a pore-filling role and also a charge-compensatory role when the amine group is protonated, and hence its overall effectiveness as a stabilizer depends upon the type of zeolite structure and the aluminum content.