The synthesis of highly reactive polyisobutylene (HRPIB) was successfully achieved via the cationic polymerization of a mixed C4 gas stream (raffinate-1) using an aluminum chloride–di-butyl ether catalytic complex (AlCl3·Bu2O) in pure n-hexane. The use of mixed C4 feedstock instead of pure isobutylene (IB) for the production of HRPIB can create significant financial benefits and reduce overall production costs. The optimal molar ratio of AlCl3 to Bu2O for catalytic activity and selectivity toward β-H abstraction to form HRPIB was determined to be 1:1. The effects of temperature, reaction time, catalyst concentration, and Bu2O amount on the polymerization reaction were investigated. HRPIB was successfully synthesized within the temperature range of 0°C to +20°C, with molecular weight (Mn) in the range of 500–5000 and a terminal vinylidene group content exceeding 80%. This study contributes to the development of a more efficient, cost-effective, and environmentally friendly method for producing HRPIB on an industrial scale compared to conventional processes, which usually require extremely low temperatures and hazardous conditions
