Magnetic Resonance Imaging (MRI)

Abstract

Magnetic resonance imaging (MRI) and spatially resolved nuclear magnetic resonance (NMR) spectroscopy (MRS) can provide a broad variety of useful information about the processes inside heterogeneous catalysts and catalytic reactors. In particular, heat and mass transport processes, chemical composition and reaction conversion, etc., can be visualized and quantified with MRI noninvasively and with spatial resolution. As NMR-based techniques are inherently spectroscopic, they are naturally suited for operando studies of catalysts and reactors under working conditions. However, applications of the MRI/MRS techniques for the studies of catalytic processes are anything but routine because of a number of technical limitations, the specifics of the instrumentation required for such experiments, and more significantly – because of the limited sensitivity of the NMR-based techniques. Fortunately, spin hyperpolarization techniques of modern magnetic resonance are able to boost the sensitivity of NMR-based methods by 3–4 orders of magnitude and more, opening new possibilities for the development of mechanistic and imaging operando and in situ tools for heterogeneous catalysis. In particular, catalytic hydrogenation of unsaturated compounds with parahydrogen is a promising route toward a significant enhancement of sensitivity in magnetic resonance.