Zeolites are unique minerals with a cage-like structure that can trap small molecules and ions passing through them. This interesting ability renders them extremely useful in various industries such as the pharmaceutical and petrochemical industries. However, their complex, disordered nature makes them particularly difficult to study. Fortunately, this is set to change as a team of scientists led by Dr Paul Donaldson have devised and demonstrated a new and effective way of investigating zeolites using advanced infrared (IR) spectroscopy.
This landmark research explores how advanced femtosecond 2D-IR laser spectroscopy, a technique currently only offered by the CLF's Ultra facility, can offer a new and better way to study zeolites. The team first designed an approach to collect data from zeolite powders using 2D-IR spectroscopy, and then conceived several ways of studying their characteristics.
In particular, the effectiveness of these new techniques were demonstrated by shedding light on issues surrounding a curious defect in zeolites called 'silanol nests' (Fig 1). These structures appear to influence the properties of certain zeolites but are challenging to distinguish and quantify. The new 2D-IR laser technique was not only able to do both but also managed to uncover a unique signature of silanol nests – their 'wobbling' on a picosecond timescale! This behaviour is unlike that of any other structures found within zeolites, which all have atoms that are locked firmly in place.
Fig 1. Silanol nests in zeolites. (Image credit: https://doi.org/10.1039/D4SC08093A)
The publication of this research comes after thousands of spectroscopy measurements taken over several years, with the team facing various setbacks, difficulties and dead ends along the way. Paul and his team hope that this study will inspire zeolite scientists to exploit the new IR tools available at Ultra, the only facility in the world able to carry out these kinds of measurements, to help support and further their research. Better research into zeolites will in turn support the development of their various applications, which range from water softeners in detergents, odour trappers, and radioactive particle removers, to catalysts used for speeding up chemical processes in the pharmaceutical and petrochemical industries.
Read the research paper here.
