Kinetic study of the liquid-phase hydrogenation of 1-butyne over a commercial palladium/alumina catalyst

Hydrorefining of C4 cuts of unsaturated hydrocarbons involves the selective removal of 1-butyne by catalytic hydrogenation. Due to its technological relevance, we investigated the hydrogenation of 1-butyne over a commercial palladium-based catalyst of the eggshell type. The experimental conditions were selected to reproduce those of industrial hydrorefining reactors: liquid-phase reaction, seven levels of temperature between 27 and 62 °C, initial concentrations of 1-butyne up to 0.6 mol/l and hydrogen partial pressure ranging from 0.8 to 8 atm. Under these conditions, the overall effectiveness factor of 1-butyne hydrogenation was less than 0.15. Provided that hydrogen was the limiting reactant inside the active shell, 1-butene was the only product yielded by 1-butyne hydrogenation. The regression analysis of experimental data corresponding to the hydrogenation of 1-butyne to 1-butene was restricted to experimental compositions in which 1-butyne concentration was higher than 0.07 mol/l. An intrinsic kinetic expression with reaction orders 1 and −1 for hydrogen and 1-butyne, respectively, predicts experimental data with an average deviation of 2.1%. Estimates of the activation energy and kinetic coefficient at 44 °C are (1.55 ± 0.06) 104 cal/mol and (4.6 ± 0.1) mol/(kg s).