Abstract:

Deep eutectic solvents (DESs) are widely used in oxidative desulfurization. It is great significance to develop novel DESs and further improve the desulfurization performance. ChCl/2Ph type DESs was synthesized using choline chloride (ChCl) as hydrogen bond acceptor and phenol (Ph) as hydrogen bond donor. The hydrogen bonding interaction between Ph and ChCl was confirmed by FT-IR and ¹H NMR. Dibenzothiophene (DBT) was removed from the model oil using ChCl/2Ph as extractant, hydrogen peroxide as oxidant and Ti(SO₄)₂ as catalyst. The effects of reaction temperature, V(ChCl/2Ph)/V(Oil), n(H₂O₂)/n(S), the amount of catalyst and different sulfur compounds on the desulfurization rate were investigated. The results show that the optimum reaction conditions are as follows: 5 ml model oil, V(ChCl/2Ph)/V(Oil) =2∶10, n(H₂O₂)/n(S) = 6, and catalyst dosage of 0.01 g, reaction temperature of 40℃, reaction time of 180 min. Under above conditions, the desulfurization rate can reach to 98.2%. The apparent activation energy of the system is 41.9 kJ/mol. The deep eutectic solvent phase containing catalyst can be reused for 5 times without significant decrease in activity. The study of desulfurization mechanism shows that the formation of Ti peroxides and Br?nsted acid is the key to the high desulfurization activity of the system.

Key words: deep eutectic solvent, catalyst, solvent extraction, oxidative desulfurization, activation, recovery

摘要：

低共熔溶剂广泛应用于氧化脱硫过程，开发新型的低共熔溶剂并进一步提升脱硫效果具有重要的意义。 以氯化胆碱为氢键受体，苯酚为氢键供体合成了ChCl/2Ph型低共熔溶剂。通过FT-IR和¹H NMR证实了苯酚和氯化胆碱之间存在氢键作用。以苯酚型低共熔溶剂为萃取剂，双氧水为氧化剂，硫酸钛为催化剂氧化脱除模拟油中的二苯并噻吩。考察了反应温度、V(ChCl/2Ph)/V(Oil)、n(H₂O₂)/n(S)、催化剂用量以及硫化物类型对脱硫率影响。实验表明最佳反应条件如下：模拟油量为5 ml，V(ChCl/2Ph)/V(Oil)=2∶10， n(H₂O₂)/n(S)=6，催化剂用量为0.01 g，反应温度为40℃，反应时间180 min。在此条件下脱硫率可以达到98.2%。求得体系的表观活化能为41.9 kJ/mol。含有催化剂的低共熔溶剂相可以重复使用5次且活性没有明显降低。机理研究表明形成钛的过氧化物和Br?nsted酸性是具有较高脱硫活性的关键。

关键词: 低共熔溶剂, 催化剂, 溶剂萃取, 氧化脱硫, 活化能, 回收