s.a Foruzandeh - Iran polymer and petrochemical institute (IPPI), P.O. Box ۱۴۹۶۵/۱۱۵, Tehran, Iran.
m Nekoomanesh - Iran polymer and petrochemical institute (IPPI), P.O. Box ۱۴۹۶۵/۱۱۵, Tehran, Iran.
f Ziaee - Iran polymer and petrochemical institute (IPPI), P.O. Box ۱۴۹۶۵/۱۱۵, Tehran, Iran.
b Jafari - Iran polymer and petrochemical institute (IPPI), P.O. Box ۱۴۹۶۵/۱۱۵, Tehran, Iran.

A homogenous chromium-based catalyst system consisted of [Cr(III) tris(2- ethylhexanoate)/2,5-dimethylpyrrole/AlEt3/1,1,2,2-tetrachloroethane], was used for synthesizing 1- hexene at high productivity & selectivity. GC-Mass analysis was used to investigate the effect of the variation of Al/Cr molar ratio on the productivity, selectivity of the 1-hexene and the formation selectivity and catalytic activity was investigated. The Al/Cr molar ratio has significant effect on both 1-hexene and the formation of high polymer. The molar ratio of Al/Cr varied from o to 136. In the range studied it was shown that both productivity & selectivity first increases with increasing the Al/Cr ratio, passing through a maximum & then reducing with more Al/Cr. The maximum Al/Cr for productivitywas 55 & for selectivity was 40. Moreover polymer formation showed quiet different trend. i.e. no polymer formation was observed with Al/Cr up to 55, while with at higher ratio of Al/Cr, ascending polymer formation was reported

1-Hexene, Trimerization, Chromium catalyst, Ethylene Oligomerization