Pd nanoparticles on hydrotalcite as an efficient catalyst for partial hydrogenation of acetylene: Effect of support acidic and basic properties

Abstract

Support effects, especially effects of surface acidity and basicity on the status of metals and on catalytic performance in partial hydrogenation of acetylene, were investigated over hydrotalcite (HT)-, MgO-, and Al2O3-supported Pd catalysts. Pd/HT exhibited the highest activity and selectivity when compared with Pd/MgO and Pd/Al2O3. This activity was reasonably attributed to the high dispersion (34.6%) because of abundant low-coordinated sites, as determined by CO infrared spectroscopy (IR) analysis. By means of X-ray photoelectron spectroscopy and CO-IR, the interaction between the support and Pd was revealed: the basic sites increased the surface electron density of Pd; conversely, the acidic sites resulted in an electron-deficient surface. A possible mechanism, that the huge population of active sites originated from the redispersion of Pd atoms by interaction with acidic sites on HT, was then proposed.