A new chromium-based catalyst coated with paraffin for ethylene oligomerization and the effect of chromium state on oligomerization selectivity
A new chromium-based catalyst coated with paraffin for ethylene oligomerization and the effect of chromium state on oligomerization selectivity
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DOI：
10.1016/s0926-860x(02)00239-9
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发表时间：
2002-08-30
影响因子：
5.5
通讯作者：
Hu, YL
中科院分区：
文献类型：
--
作者：
Fang, YQ;Liu, YX;Hu, YL
提出了一种以铬（III）三（2-乙基己酸酯）(Cr（EH)(3)）、2,5-二甲基吡咯（2,5- dmp）、GeCl4和固体石蜡包覆的三乙基铝（TEA）为载体的铬基催化剂体系用于乙烯齐聚反应的新方法。GC-MS和H-1-NMR分析表明，通过这种方法制备的涂层催化剂体系对空气不敏感，因此可以在环境条件下储存。催化剂对1-己烯的选择性高达97.91 wt.%，在空气中暴露24h时，选择性略有下降；相比之下，未涂覆的选择性仅为35.6%。XPS分析表明，大气中氧与催化剂的吸附使铬的化学态由Cr3+转变为Cr6+。这种变化反过来又显著降低了它对1-己烯的选择性。(C) 2002 Elsevier Science B.V.版权所有
A new method is proposed in which a chromium-based catalyst system containing chromium(III) tris (2-ethylhexanoate) (Cr(EH)(3)),2,5-dimethylpyrrole(2,5-DMP), GeCl4 and triethylaluminum (TEA) coated with solid paraffin is used for oligomerization of ethylene. GC-MS and H-1-NMR analyses show that the coated catalyst system prepared via this approach is air-insensitive so it can be stored under ambient conditions. The selectivity for 1-hexene is up to 97.91 wt.%, and only slightly decreases when the catalyst system is exposed in air for 24h; in contrast, the selectivity is only 35.6% for its non-coated counterpart. XPS reveals that an attachment of atmospheric oxygen to catalyst makes the chemical state of chromium change from Cr3+ to Cr6+. Such a change, in turn, reduces remarkably its selectivity for 1-hexene. (C) 2002 Elsevier Science B.V. All rights reserved.