A study of the liquid-phase hydrogenation of 1,3-butadiene on commercial Pd/Al2O3 catalysts of the "egg-shell" type has been performed. Experimental conditions (40 degreesC, 4 atm and high conversion of the di-olefin) were selected in accordance to industrial operating conditions employed for selective hydrogenation of 1,3-butadiene. Three experimental schemes were tested: a slurry reactor, a rotating-basket reactor, and a recirculation system with an external fixed-bed reactor. Significant drawbacks shown by the two former devices were mainly derived from the very high activity and the egg-shell structure of the catalysts. Instead, the recirculation system was found to be an excellent alternative. Although Pd is present only within a very thin external layer (around 50-250 mum), strong diffusion effects impairing selectivity were observed. Plausible kinetic expressions corresponding to nine series-parallel overall reactions are derived from a mechanistic model. To deal with this network of fast reactions, a rather complex set of computational and predictive tools were employed. A worked out example from several replicates demonstrates the capability of both, experimental and data analysis procedures, for inferring kinetic parameters of the proposed model. (C) 2001 Elsevier Science B.V. All rights reserved.