1.0-0.03% Pd/Al2O3 catalysts with a primary (70-90%) particle size of 9, 15, 25 and 75 angstrom have been synthesized. It has been shown that, with ail increasing palladium particle size in this order, the selectivity of the catalysts during the hydrogenation of the acetylene impurity (approximately 1 wt.%) in an ethane-ethylene fraction decreases.