The refined utilization of various parts of hybrid residual C4 has received increasing attention, but the mixed C4 is difficult to separate due to complex components and close boiling points. This paper proposes an innovative separation method using complex extractive distillation by adding cuprous chloride ethanolamine (C2H7NO–CuCl) into the conventional extractant, as a complexing agent. The vapor–liquid equilibrium (VLE) data were measured for six different systems, namely, the mixed C4–dimethylformamide (DMF) system and the mixed C4–DMF–C2H7NO–CuCl system, the mixed C4–acetonitrile (ACN) system and the mixed C4–ACN–C2H7NO–CuCl system, and the mixed C4–methyl–ethyl ketone (MEK) system and the mixed C4–MEK–C2H7NO–CuCl system. Results showed that the relative volatility of butane–butene solution was significantly increased with the addition of the complexing agent systems. After careful consideration of various influencing factors, the mixed C4–MEK–C2H7NO–CuCl system was selected as the best extraction separation system, and technological experiments were carried out to further explore its feasibility and advanced nature. Results showed that when the solvent-to-feed ratio (S/F) was 12.5, the reflux ratio of extractive distillation column (R 1) was 1.5, and the reflux ratio of solvent recovery column (R 2) was 2.5, the purity of butene was more than 97.0%, and the separation yield was more than 95.0%. Furthermore, the solvent-to-feed ratio of complex extractive distillation was only 70% of ordinary extractive distillation, the reflux ratio was only 60% of ordinary extractive distillation, and the stripping temperature of the complex extractive distillation column was only about 423.15 K, which was lower than that of the ordinary extractive distillation column.

This paper investigates the selective oligomerization of isobutene in mixed C4 using ethanol as an inhibitor. The effects of ethanol/isobutene, reaction temperature, and reaction space velocity on isobutene oligomerization were examined using two β molecular sieve catalysts. The results indicate that the optimal reaction conditions, at the same calcination temperature, are as follows: The mass ratio of ethanol to isobutylene is 20%, the reaction pressure is 1 MPa, the reaction temperature is 65°C, the reaction space velocity is 2 h−1, the dimerization product C8 has fewer types, and the selectivity can reach over 15%. After adding ethanol, there is a significant inhibitory effect on n‐butene. Furthermore, we used reactive distillation technology to simulate isobutene oligomerization. By optimizing the sensitivity of the tower's operating conditions, we obtained the optimal operational parameters of the tower. Under optimal operating conditions, the conversion rate of isobutene can reach over 80%. The mass fraction of C8 in the oligomerization product accounted for 57.44%, C12 accounted for 8.29%, and ETBE accounted for 34.23%. The reactive distillation technology can improve product selectivity.