Liquid-phase hydrogenation kinetics of isooctenes on Co/SiO2

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 (E-app 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. (C) 2003 Elsevier B.V. All rights reserved.