Chemical Imaging of Solid Catalysts with Nano-Infrared Spectroscopy

Chemical Imaging of Solid Catalysts with Nano-Infrared Spectroscopy
1st supervisor and 1st promotor: Prof. Bert Weckhuysen
Affiliation: Utrecht University
Research theme: Catalyst Diagnostics to Develop More Active Catalysts

Understanding the active site and its dynamics in a solid catalyst is vital to develop better ones. Such understanding can only be obtained when we have sensitive tools to chemically image solid catalysts, preferentially at the nanoscale. Scanning probe methods, such as Scanning Near-Field Optical Microscopy (SNOM), can overcome the diffraction limit of light, and in particular the scattering-type version s-SNOM combines a high-spatial-resolution of ~ 10 nm with ultra-sensitivity, in principle down to the single molecule level, by spatially confining the light-matter interaction. Photoinduced force microscopy (PiFM) is a promising SNOM technique, which probes the dipole-dipole moment interaction between the AFM tip and catalyst.

In this work, we will build further on our work to use a recently acquired PIFM instrument to chemically image zeolite, metal organic framework and zeolitic imidazolate framework thin-films. We propose to investigate zeolite-based model catalysts, differing in their composition (Al content) and framework structure (i.e., MFI, FAU and BEA); and study with IR sensitive probe molecules (e.g. pyridine) their local acidity, as well as the local concentration of Al framework atoms. In a second stage of the study, we will investigate catalytic reactions to explore the reactivity of the zeolite-based model catalysts.

Keywords:

• Chemical Imaging
• Active Site
• IR Nano-spectroscopy
• Atom Force Microscopy
• Mechanistic understanding