Investigations on the relative effectiveness of some tertiary alkanolamines in the synthesis of large-crystal zeolite NaA

The relative efficiency of four different tertiary alkanolamines as nucleation suppressors in the synthesis of large-crystal zeolite NaA has been investigated by systematically varying the amount of each in synthesis solutions and following the phase and particle size of zeolites obtained. One additive, 2,2-bis (hydroxymethyl)-2,2′,2″-nitrilotriethanol, was found to be considerably more effective than the best previously known nucleation suppressor, 2,2′,2″-nitrilotriethanol (triethanolamine), yielding large zeolite NaA crystals at appreciably lower solution additive concentrations. In addition, a spherical phase that was formed in competition to large-crystal zeolite NaA was identified as LOSOD, rather than as the previously suggested NaP. The crystallization of LOSOD was found to be suppressed by increased solution NaOH concentration, allowing the synthesis of larger zeolite NaA crystals.