Non-thermal RF plasma effects on surface properties of Pd/TiO2 catalysts for selective hydrogenation of acetylene

Abstract

Non-thermal RF plasma modification has been applied to Pd/TiO2 catalysts for selective hydrogenation of acetylene in the presence of ethylene. High ethylene selectivity and high acetylene conversion were obtained over 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), Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) with CO and temperature-programmed desorption with ethylene (C2H4-TPD). XPS and H2-DSC results confirmed that supported Pd precursors could be effectively reduced to the metallic state during the room temperature plasma treatment. Plasma treatments also enhanced the surface active sites of Pd/TiO2 catalysts and improved the dispersion of Pd metal particles. In addition, DRIFTS and C2H4-TPD results indicated that plasma treatments could induce strong metal-support interaction with lower reduction temperature (200°C), which lead to an enhanced catalytic performance on selective hydrogenation of acetylene. It demonstrates that the RF non-thermal plasma treatment is an effective way to manipulate surface properties and the interaction between metals and supports of supported Pd catalysts for selective hydrogenation.