Influence of process parameters on the reaction kinetics of the chromium-catalyzed trimerization of ethylene.
Influence of process parameters on the reaction kinetics of the chromium-catalyzed trimerization of ethylene.
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DOI：
10.1002/chem.201000533
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发表时间：
2010-07
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通讯作者：
A. Wöhl;W. Müller;Stephan Peitz;N. Peulecke;B. Aluri;Bernd H. Müller;D. Heller;U. Rosenthal;Mohammed H. Al-Hazmi;Fuad M Mosa
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作者：
A. Wöhl;W. Müller;Stephan Peitz;N. Peulecke;B. Aluri;Bernd H. Müller;D. Heller;U. Rosenthal;Mohammed H. Al-Hazmi;Fuad M Mosa
本文报道了一种新型乙烯三聚催化剂体系的动力学实验研究结果，该体系由铬源[CrCl（3）（thf）（3）]（thf=四氢呋喃）、Ph（2）P-N（iPr）-P（Ph）-N（iPr）H（PNPNH）配体（Ph=苯基，iPr=异丙基）和三乙基铝（AlEt（3））活化剂组成。可以表明，初始活性显示出对乙烯浓度的一级依赖性。此外，一阶依赖性被发现的催化剂浓度。初始活性遵循典型的Arrhenius行为，实验测定的活化能为52.6 kJ mol（-1）。在高温下（约。80 ℃）时，观察到显著的失活，这可以暂时追溯到AlEt（3）存在下的配体重排。在一个快速的初始阶段之后，观察到乙烯吸收曲线中的明显的“扭结”，随后是缓慢的、几乎线性的、总乙烯消耗的进一步增加。催化剂组成，特别是配体/铬和助催化剂/铬摩尔比，对乙烯三聚的催化性能具有强烈影响。
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.