Title: Can the combination of in situ differential impedance spectroscopy and 27Al NMR detect incongruent zeolite crystallization?

Abstract: Crystallizing zeolites with isotropic properties is critical to the chemical industry but can be extremely challenging as small deviations in the synthesis conditions can have extreme effects on the final products. Easily implemented in-situ monitoring systems could make a real difference, but very few experimental methodologies cater to the specific needs of applications relying on harsh, hyper-alkaline conditions involving multiphasic systems such as Hydrated Silicate Ionic Liquids. Differential impedance spectroscopy (DIS) promises to enable such studies. It remains highly accurate despite possible electrode degradation or scaling. This study showcases how in-situ differential impedance measurements not only enable reliable detection of crystallization of even minimal amounts of zeolite product but also illustrates how the unique combination of in situ DIS and in situ, 27Al NMR provides insight into complex, incongruent zeolite crystallization processes.