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/alpha-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. O-2, 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. Further-more, the sites involving direct ethane formation from acetylene could be suppressed by NO, treatment. (C) 2002 Elsevier Science B.V. All rights reserved.