Influence of process parameters on the reaction kinetics of the chromium-catalyzed trimerization of ethylene.
In this paper we report the results of an extensive experimental kinetic study carried out on the novel ethylene trimerization catalyst system, comprising the chromium source [CrCl(3)(thf)(3)] (thf=tetrahydrofuran), a Ph(2)P-N(iPr)-P(Ph)-N(iPr)H (PNPNH) ligand (Ph=phenyl, iPr=isopropyl), and triethylaluminum (AlEt(3)) as activator. It could be shown that the initial activity shows a first-order dependency on the ethylene concentration. Also, a first-order dependency was found for the catalyst concentration. The initial activity follows a typical Arrhenius behavior with an experimentally determined activation energy of 52.6 kJ mol(-1). At elevated temperatures (ca. 80 degrees C), a significant deactivation was observed, which can be tentatively traced back to a ligand rearrangement in the presence of AlEt(3). After a fast initial phase, a pronounced 'kink' in the ethylene-uptake curve is observed, followed by a slow, almost linear, further increase of the total ethylene consumption. The catalyst composition, in particular the ligand/chromium and the cocatalyst/chromium molar ratio, has a strong impact on the catalytic performance of the trimerization of ethylene.
Wöhl
Anina
A
Linde AG, Linde Engineering Division, Dr.-Carl-von-Linde-Strasse 6-14, 82049 Pullach, Germany.
Müller
Wolfgang
W
Peitz
Stephan
S
Peulecke
Normen
N
Aluri
Bhaskar R
BR
Müller
Bernd H
BH
Heller
Detlef
D
Rosenthal
Uwe
U
Al-Hazmi
Mohammed H
MH
Mosa
Fuad M
FM