Figure 4. Intermolecular exchange of hydrogen atoms (IEHA) on bulk metal and nanoparticle surfaces.

¹H NMR spectra of propene hydrogenation reaction with parahydrogen produced from parahydrogen converter at 77 K under the following conditions and gas mixtures. (a) using 100% hydrogen gas; (b) 50/50% hydrogen/deuterium gas mixture; (c) 50/50% hydrogen/deuterium gas mixture in contact with platinum metal before flowing into a parahydrogen converter and (d) 50/50% hydrogen/deuterium gas mixture in contact with TiO₂ supported p-MBA-capped platinum nanoparticles before flowing into the parahydrogen converter. The PHIP NMR signal in (c) and (d) is a factor of two less than (b). This confirms that IEHA occurs on both metal and supported nanoparticles if sufficient catalyst is present across the bed in a gas flowing system.