Selection and process optimization of ionic liquids for desulfurization

doi:10.11949/j.issn.0438-1157.20170182

Abstract

Abstract:

To verify the reliability of ionic liquids' molecular design method based on COSMO-SAC model, ionic liquids desulfurization mechanism analysis and experimental results are compared with COSMO simulation. By analyzing[HMIM] [BF₄],[HMIM] [PF₆],[BMIM] [BF₄],[BMIM] [PF₆],[EMIM] [BF₄] and[EMIM] [PF₆] on mechanism level,[HMIM] [PF₆] was considered as a better extractive desulfurization agent than others, and the order of desulfurization efficiency was consistent with the calculation results from COSMO-SAC model. The experimental result shows that the difference between the COSMO simulation and experiments is not significant. In this study,[HMIM] [PF₆] was used as an extractive desulfurization agent to remove benzothiophene from fuels, and the change of sulfur content in model oil was determined by liquid chromatography. Through considering the effect of extraction temperature, time and the ratio of solvent to oil, the optimal operating conditions, 20℃, 40 min and 2:1 respectively, were determined in orthogonal experiment with an efficiency over 72.74%. With[HMIM] [PF₆] used as the deep extraction desulfurization solvent, the sulfur content decreased from 1200 μg·g^-1 to 6.98 μg·g^-1 by 4-stages extraction, which met the Phase Ⅴ Emission Standards in China.

Key words: ionic liquids, extraction, desulfurization, simulation, orthogonal experiment

摘要：

针对基于COSMO-SAC模型分子设计方法的准确性问题，采用离子液体脱硫机理分析和实验的方法对其进行了验证，即对[HMIM] [BF₄]、[HMIM] [PF₆]、[BMIM] [BF₄]、[BMIM] [PF₆]、[EMIM] [BF₄]、[EMIM] [PF₆] 6种离子液体作萃取剂时的脱硫效果进行了脱硫机理的分析和实验的验证，得到的脱硫性能排序与离子液体分子设计结果基本一致，且均认为[HMIM] [PF₆]脱硫率较高。以[HMIM] [PF₆]为萃取剂，通过液相色谱法测定萃取后的液相组成，考察萃取时间、萃取温度、剂油比3个因素对脱硫率、分配系数和选择性系数的影响。通过正交实验设计确定了萃取时间40 min、萃取温度20℃、剂油比2：1为较优操作条件，单次脱硫率为72.74%，四级萃取可将模型油的含硫量由1200 μg·g^-1降至6.98 μg·g^-1，符合国Ⅴ标准。

关键词: 离子液体, 萃取, 脱硫, 模拟, 正交实验

CLC Number:

TQ028.3

FANG Jing, ZHANG Shuting, LI Tingting, LI Chunli. Selection and process optimization of ionic liquids for desulfurization[J]. CIESC Journal, 2017, 68(9): 3434-3441.

方静, 张淑婷, 李婷婷, 李春利. 离子液体用于燃油萃取脱硫的选择与过程优化[J]. 化工学报, 2017, 68(9): 3434-3441.

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