In Situ Monitoring of Heterogeneous Catalytic Hydrogenation via ¹²⁹Xe NMR Spectroscopy and Proton MRI

The ability to use molecular hydrogen, H₂, as a buffer gas in spin exchange optical pumping of noble gases enables the production of hydrogen gas containing a low percentile (5%) of hyperpolarized (HP) ¹²⁹Xe as a tracer for in situ NMR spectroscopy of hydrogenation reactions. It is demonstrated that the xenon chemical shift, observed in the porous space of Pt-containing alumina pellets, can be used to monitor the temperature changes under rapidly progressing, nonsteady-state conditions during start-up of the catalytic reaction. Standard proton MR imaging was successfully applied to provide in situ evaluation of conversion for the catalyst used in this work.