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Influence of Process Parameters on the Reaction Kinetics of the Chromium‐Catalyzed Trimerization of Ethylene
Author(s) -
Wöhl Anina,
Müller Wolfgang,
Peitz Stephan,
Peulecke Normen,
Aluri Bhaskar R.,
Müller Bernd H.,
Heller Detlef,
Rosenthal Uwe,
AlHazmi Mohammed H.,
Mosa Fuad M.
Publication year - 2010
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201000533
Subject(s) - ethylene , catalysis , chromium , chemistry , tetrahydrofuran , ligand (biochemistry) , arrhenius equation , ethylene glycol , kinetics , activation energy , isopropyl alcohol , isopropyl , polymer chemistry , inorganic chemistry , medicinal chemistry , organic chemistry , biochemistry , receptor , physics , quantum mechanics , solvent
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( i Pr)‐P(Ph)‐N( i Pr)H (PNPNH) ligand (Ph=phenyl, i Pr=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 °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.