The selective hydrogenation of 1,3-butadiene to 1-butene with toluene as a co solvent is studied experimentally over a NiPdCe/gamma-Al2O3 catalyst. To reduce mass transfer limitations, an egg-shell catalyst is used in a fixed-bed reactor for liquid-phase hydrogenation of 1,3-butadiene at 40 degrees C and two pressure levels, 90 and 210 psig. Experimental results indicate that 1,3-butadiene conversion and selectivity of the hydrogenation process are improved when toluene is added. Conversion of 1,3-butadiene increases from 65% without toluene to 75% for 20% toluene concentration at 90 psig, while for 210 psig the observed increase is from 66% to 81%. The 1,3-butadiene selectivity toward 2-butenes is favored against 1-butene, always with preference for the thermodynamically stable trans-isomer. The 1-butene hydrogenation is controlled, decreasing the loss from 25% to 10% in the presence of toluene a 210 psig. It can be concluded that the toluene presence enhances the 1,3-butadiene selective hydrogenation and controls 1-butene consumption. (C) 2013 Elsevier Ltd. All rights reserved.