Synthesis of palladium nanoparticles in carbon dioxide induced reversible ionic liquids and their application

We synthesized Pd particles in reversible ionic liquid formed by carbon dioxide induction of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and 1-hexanol solution. Transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS) were used to characterize their morphology and size. The particles have smaller size and more uniform size distribution compared with those synthesized in the mixed solution without carbon dioxide. The particles size obtained by TEM is obviously larger than that obtained by SAXS, which indicates the aggregation of the Pd particles in the separation and washing processes of TEM characterization. Then we studied the catalytic performance of Pd nanoparticles in p -nitrotoluene and 2-nitrobenzaldehyde hydrogenation reaction. The results showed that the nanoparticles have high catalytic activity and selectivity for nitro group with aldehyde group unchanged.