Abstract: Using C4 fraction from PetroChina Lanzhou Petrochemical Company as raw material, desulfurization tests by solvent extraction were carried out to select optimum desulfurization agent and method, as well as to study the process conditions and agent regeneration conditions. Results showed that SW-I was the optimum desulfurization agent, which had a C4 fraction solubility of 6.53×10-5 g/g only. By comparing liquid-liquid extraction method and gas-liquid absorption method, it was shown that gas-liquid absorption method was more suitable. When adopting 3-stage gas-liquid absorption method and SW-I desulfurization agent, under a reaction temperature of 20 ℃, an extractant space velocity of 0.15 h-1 and C4 fraction space velocity of 350 h-1, the sulfur content of treated C4 fraction dropped from 198.9 μg/g to 7.5 μg/g with a desulfurization rate of 96.23%. The sulfur-rich absorption agent could be regenerated by hot air stripping. When regeneration temperature was 70 ℃, solvent space velocity was 1.02 h-1 and hot air space velocity was 291 h-1, the desulfurization rate of regenerated agent was 96.03%, indicating that the regeneration rate of the desulfurization agent reached 99.80%.

Key words: refinery C4 fraction, desulfurization agent, organic sulfide; solvent extraction