Determination of Kinetic Constants for Titanium-based Ethylene Trimerization Catalysis

2006-05-10T00:00:00Z (GMT) by Henk Hagen
For two titanium-based ethylene trimerization catalysts, [(Me<sub>3</sub>SiC<sub>5</sub>H<sub>3</sub>CMe<sub>2</sub>C<sub>6</sub>H<sub>3</sub>Me<sub>2</sub>)TiCl<sub>3</sub>] (<b>1</b>) and [(Me<sub>3</sub>SiC<sub>5</sub>H<sub>3</sub>C(CH<sub>2</sub>)<sub>5</sub>C<sub>6</sub>H<sub>3</sub>Me<sub>2</sub>)TiCl<sub>3</sub>] (<b>2</b>), the entropies and enthalpies of activation for the ethylene trimerization reaction (<i>k</i><sub>1</sub>) as well as the catalyst deactivation reaction (<i>k</i><sub>d</sub>) have been determined. Using a combination of, on the one hand, experimental pressure and temperature data and, on the other hand, vapor−liquid equilibrium calculations, the 1-hexene concentration as a function of time was estimated and these data were fitted to a kinetic model to obtain the thermodynamic data. A best fit was obtained for a combination of a propagation reaction that is first order in the ethylene concentration and a catalyst deactivation reaction that is second order in the catalyst concentration. The measured entropies and enthalpies of activation are in good agreement with the previously reported calculated ones.