Synthesis of ferrierite zeolite with pyrrolidine as structure directing agent: A combined X-ray diffraction and computational study

The zeolite ferrierite has been synthesized in fluoride medium in the presence of pyrrolidine as structure directing agent (SDA). The templating role of pyrrolidine molecules in the crystallization process has been studied by combining X-ray Rietveld refinement and computational calculations. Pyrrolidine molecules are accommodated in two sites, one within the ferrierite cavity, and another in the widest section of the 10-ring channel, with the plane of the molecule perpendicular to the first. Both molecules show well-defined positions, with little freedom to move away from its most stable location, indicating the good fit of pyrrolidine to the ferrierite topology. This implies a strong templating role played by pyrrolidine in the crystallization of ferrierite, acting as a true template rather than a mere pore-filling agent as previously proposed due to its ability to act as structure directing agent for more than one structure.