Abstract
Transition metals such as Ni, Co, Ti and Zr and several alkylaluminum promoter were studied as catalyst for oligomerization of ethylene. In the case of Ni and Co catalysts, termination reactions with β-hydrogen elimination are dominant, light products such as butenes are mainly produced and the purity of linear α-olefin are low.
Ti(IV) is so easily reduced to Ti(III) that high molecular weight polymer is mainly produced. In the case of Ti catalyst, to obtain α-olefin in high selectivity, alkylaluminum with weaker reducing power should be used for the oligomerization of ethylene at below room temperature. Under these lower temperature, a small amount of polymer by-products are crystallized and continuous operation is prevented.
In the case of Zr catalyst, the reaction can be carried out at relatively higher temperature in which polymer can be melted because Zr is stable for reduction compared with Ti, then continuous operation is possible.
Zr complex catalyst with three components consisting of ZrCl4, TEA and EASC is convenient for oligomerization of ethylene.
The new catalyst has high activity, high selectivity of α-olefin, good product distribution, and good stability.
The performance of the Zr catalyst with these three components vary by the order of components and synthesis conditions (temperature, contact time and concentration).
By using binary system of TEA and EASC as alkylaluminum, product distribution (α value) can be controlled freely with high activity of catalyst by changing the ratio of TEA and EASC.
