Method for producing polybutene

A method of producing high reactive polybutene, comprising the steps of:

• preparing a catalyst system including secondary alkylether, tertiary alcohol, and boron trifluoride;
• introducing the catalyst system to a polymerizing reaction of (a) isobutene, (b) C4 hydrocarbon compounds derived from cracking of naphtha and containing more than 10 weight % of isobutene, or (c) C4 hydrocarbon compounds derived from a refining process of crude oil or from catalytic cracking of heavy gas oil and containing more than 10 weight % of isobutene, to form a polymerization product;
• and
• stripping the polymerization product to generate high reactive polybutene having a 300˜5000 number average molecular weight, wherein the amount of boron trifluoride is 0.05˜1.0 weight part per 100 weight part of isobutene, the mole ratio of a co-catalyst including secondary alkylether and tertiary alcohol:boron trifluoride is 1.0˜2.0:1, and the mole ratio of secondary alkylether:tertiary alcohol is 0.5˜1.2:1.