AN ANALYSIS OF MASS-TRANSFER AND KINETICS DURING ETHYLENE OLIGOMERIZATION OVER NICKEL SULFATED ALUMINA CATALYST IN A SLURRY REACTOR

The reaction kinetics of ethylene oligomerization was investigated ove r the temperature range 278-323 K and near-atmospheric pressure in a l aboratory slurry reactor. The nickel/sulfated alumina catalyst was pre pared by use of a non-porous fumed alumina (ALONT(TM)) support and by ion-exchange thereon of Ni ions. A first-order dependence of ethylene consumption rate on ethylene concentration in iz-heptane solvent was d etermined with an apparent activation energy of 16.3 kJ/mol. Several s ize fractions of catalyst particles were also used to study the extern al mass transfer resistance and the internal resistance to pore diffus ion and chemical reaction. The results indicate that neither of the re sistances can be ignored. The combined internal diffusion and reaction steps appear to be rate controlling for ethylene oligomerization in t he slurry reactor. The influence of gas absorption resistance was also evaluated by carrying out experiments using different charges of cata lyst mass. The selectivity to 1-C-6 increases with temperature. At tem peratures < 298 K, the dominant products are l-butene and l-hexene wit h traces of their isomers. (C) 1997 Elsevier Science Ltd.