Preparation and Selective Acetylene Hydrogenation Catalytic Properties of Supported Pd Catalyst by the in Situ Precipitation−Reduction Method

Abstract

Pd/MgAl-layered double hydroxide (LDH) was synthesized in situ on the surface of spherical Al2O3 to obtain a Pd/MgAl-LDH/Al2O3 catalyst, using hexamine as both a precipitant for LDH and a reductant for Pd2+. After calcination and reduction, another Pd/MgO-Al2O3 catalyst was obtained. As a comparison, the Pd/Al2O3 catalyst was prepared by the conventional impregnation method. Low-temperature N2 adsorption−desorption, NH3 temperature-programmed desorption, and scanning electron microscopy results showed that Pd/MgAl-LDH/Al2O3 and Pd/MgO-Al2O3 catalysts possessed larger surface area, lower surface acidity, uniform Pd particle size, and specific Pd shape compared with the Pd/Al2O3 catalyst. The catalytic performances of the catalysts were then studied in the selective hydrogenation of acetylene. In comparison to Pd/Al2O3, Pd/MgAl-LDH-Al2O3 and Pd/MgO-Al2O3 catalysts exhibited not only higher activity due to the uniform size and specific shape of Pd particles which provided more catalytic active sites but also...