Controlling the Aluminum Distribution in the Zeolite Ferrierite via the Organic Structure Directing Agent

Analysis of the structure of the zeolite ferrierite (framework type FER) synthesized using a combination of tetramethylammonium (TMA) and pyrrolidine as organic structure-directing agents (|((CH₃)₄N)_0.4((CH₂)₄NH)_3.6H_1.7|[Si_33.9Al_2.1O₇₂]) has revealed that TMA ions reside exclusively in the [5⁸6⁶8²] cavities of the FER framework, whereas pyrrolidine species are found in both the [5⁸6⁶8²] cavities and the main 10-ring channel. A similar, but not identical, arrangement of pyrrolidine molecules was found for a sample synthesized with pyrrolidine as the only SDA (|((CH₂)₄NH)_4.2H_2.2|[Si_33.8Al_2.2O₇₂])). A comparison of the two structures shows the influence of TMA on the location of pyrrolidine and the framework Al. Pyrrolidine species establish stronger interactions with the zeolitic framework than does TMA, suggesting a different ability of the amine to exert an influence on the aluminum distribution of the zeolite. These findings have implications in the catalytic performance of the samples.