(235e) Saxs and PFG-NMR Investigations of Zeolite Synthesis Mixtures

Despite intense research efforts a truly molecular description of the role of the organocation in high-silica zeolite nucleation and growth has remained elusive. In this talk I will summarize recent efforts from my laboratory that have applied two very different, yet complimentary, methods to interrogate zeolite synthesis mixtures. In the first part of the talk I will summarize small-angle X-ray scattering (SAXS) investigations that illuminate how the cation structure, presence of cosolvents, and the presence of heteroatoms impact the growth and structure of zeolite precursors/nanoparticles. In the second part of the talk NMR spectroscopy will be used to illustrate the silicate species present in these mixtures and the nature/magnitude of the forces between the organocation and silicate species. The second point is currently being investigated using pulse-field gradient NMR methods. By coupling the NMR with SAXS it is hoped that the growth rates observed via SAXS can be rationalized in the context of the organocation-silicate association strength which can readily be determined using PFG NMR via measurement of organocation self diffusion coefficients.