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

Abstract

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.