Regulating Pd/Al2O3 catalyst by g-C3N4 toward the enhanced selectivity of isoprene hydrogenation

The catalytic performance of supported metals can be influenced by impurities on support. In this work, we regulated the surface properties of commercial Pd/Al2O3 by a thermally and chemically stable polymer, graphitic carbon nitride (g-C3N4), to tune the catalytic semi-hydrogenation performance. According to the studies of X-ray photoelectron spectroscopy (XPS), in situ infrared absorption spectroscopy (IR), and temperature-programmed desorption mass spectrometry (TPD-MS), we found that the modified Al2O3–g-C3N4 can regulate the electronic properties of its neighboring Pd particles, thereby weakening the adsorption strength of mono-olefins. Additionally, the g-C3N4 deposits could store H-spillover species. As a result, the Pd/Al2O3-U7 showed an enhanced isoprene semi-hydrogenation conversion rate and selectivity compared to that of unadorned Pd/Al2O3. More importantly, this phenomenon could also be observed on different types of commercial Al2O3 and g-C3N4 precursors.