Effect of the pretreatment with oxygen and/or oxygen-containing compounds on the catalytic performance of Pd-Ag/Al2O3 for acetylene hydrogenation

Catalytic performance of Pd-Ag/-Al₂O₃ was studied for the selective hydrogenation of acetylene in the presence of excess ethylene. The catalyst activation was undertaken prior to the reaction test by the pretreatment with oxygen and/or oxygen-containing compounds, i.e. O₂, NO, N₂O, CO and CO₂. The enhancement of catalytic performances by the pretreatment was a consequence of an increase in accessible Pd sites responsible for acetylene hydrogenation to ethylene. Furthermore, the sites involving direct ethane formation from acetylene could be suppressed by NO_x treatment.