Low temperature hydrocracking of n-heptane over Ni-supported catalysts: study of global kinetics

Two kinetic models were applied to n-heptane hydrocracking on a Ni-Re/ZSM-5 catalyst over a wide range of operating experimental conditions (temperatu re = 433-493 K, and pressure = 760 mm Hg). In the first model, the hydrogen is adsorbed on the catalyst surface without dissociation, while the second model assumes hydrogen dissociation. Both models assume that the adsorptio n follows Langmuir isotherm. The molecular hydrogen associated with an acti ve site is most likely involved in the C-C bond rupture, which is concluded to be the rate controlling step in this work. The extracted intrinsic kine tics were estimated via the derivation of the reactor model. The apparent a ctivation energy for n-heptane cracking is found to be 83 kJ/mol. Both mode ls describe well the n-heptane consumption rate. The simulation results rev ealed that the hydrogen adsorption constant is smaller than the n-heptane a dsorption constant. (C) 2001 Elsevier Science B.V. All rights reserved.