Abstract: Separation and enrichment of n-alkanes from naphtha can reduce the operation cost of catalytic reformer and ethylene plant, optimize feedstock composition and improve production efficiency. Using urea and thiourea as complexing agents, 95% (w) ethanol as activating agent, and the mixture of n-octane, isoctane, methylcyclohexane and toluene in different proportions as simulated naphtha for complexing enrichment,the content of each component in complexing phase products and the yield of n-octane were investigated. The results showed that it was feasible to enrich n-alkanes in heavy naphtha by urea/thiourea complexation. The optimum reaction conditions of complexation experiment were as follows: the amount of 95%(w) ethanol activation dosage was 80 mL, the amount of simulated naphtha dosage was 60 mL, the mass ratio of urea/thiourea was 50/21, the complexation temperature was -10 ℃, and the time was 1 h. Because the presence of a small amount of aromatics has nagative impact on the separation efficiency of n-octane,in industry, aromatic hydrocarbons can be separated by extraction first.

Key words: n-alkanes, naphtha, separate, urea, thiourea, complexation reaction