Liquid-phase hydrogenation kinetics of isooctenes on Co/SiO2 Original Research Article

The kinetics of the hydrogenation of isooctenes (2,4,4-trimethyl-1-pentene, TMP-1, and 2,4,4-trimethyl-2-pentene, TMP-2) to isooctane (2,2,4-trimethylpentane) was studied on a commercial Co/SiO2 catalyst in a three-phase laboratory-scale reactor. The terminal double bond in TMP-1 was substantially faster hydrogenated than the internal double bond in TMP-2. Double bond isomerization was found to be of no importance under the applied reaction conditions. Kinetic parameters were estimated for power-law rate equations as well as for equations based on the Horiuti–Polanyi mechanism assuming competitive and non-competitive adsorption of the alkenes and hydrogen. All models described the experimental data accurately with physically reasonable values of parameters (Eapp 34–35 kJ/mol for TMP-1 and 40–43 kJ/mol for TMP-2). The hydrogenation rate per catalyst mass was considerably lower on cobalt than on nickel, evidently mainly due to the smaller number of active sites.