Selective Hydrogenation of Acetylene Over Pd/Al₂O₃ Catalysts: Effect of Non-thermal RF Plasma Preparation Methodologies

Supported palladium nanocatalysts have been reported to be active in selective hydrogenation of acetylene. In this work, non-thermal radio frequency plasma modification has been applied to Pd/Al₂O₃ catalysts for selective hydrogenation of acetylene in the presence of excess ethylene. High ethylene selectivity, good acetylene conversion activity and high TOF were obtained on the plasma-treated catalysts. To understand the plasma effect, the catalysts were characterized by differential scanning calorimetry in hydrogen (H₂-DSC), pulse H₂ chemisorption, X-ray photoelectron spectroscopy (XPS) and temperature-programmed desorption with ethylene (C₂H₄-TPD) experiments. XPS and H₂-DSC results confirmed that the Pd precursor could be effectively reduced to the metallic state during the room temperature plasma treatment. Plasma treatment also improved the dispersion of Pd particles with strong interaction between Al₂O₃ support and PdO and Pd nitrate precursors. In addition, C₂H₄-TPD indicated that plasma treatment could lead to an enhanced catalytic performance on selective hydrogenation of acetylene. It demonstrates that the non-thermal RF plasma treatment is an effective way to manipulate surface properties and the interaction between metals and supports of supported Pd catalysts for selective hydrogenation.