Study On Removal Of Sulfide From Marine Residual Fuel Oil By Extraction Of Ionic Liquids

The extraction desulfurization technology involved in ionic liquids has attracted much attention because of its simple requirements for process equipment and mild reaction conditions.This study focus on this direction and hotspot research area,the ionic liquids directly extract and extract combined with oxidate to remove the sulfur component from the marine residual fuel oil,systematically studied the removal effect of sulfide in heavy diesel oil.The main contents of the experiment include the following three parts.Firstly,the direct desulfurization performance of four ionic liquids（[Bmim]BF₄,[Bmim]PF₆,[Omim]PF₆,and[Bmim]Br）has been investigated.After changing the reaction conditions（extraction time,extraction temperature,ratio of IL to oil,number of extraction stages）,the sulfur content in heavy diesel oil was detected.The experimental results show that[Bmim]BF₄ and[Bmim]PF₆ have better desulfurization effect,and the desulfurization rate is proportional to the ratio of IL to oil and extraction time.The optimal ratio of IL to oil is 1:2;the optimal extraction time is 30 min and 40 min,respectively.The optimal desulfurization temperature is 40°C and 60°C,respectively.The single-stage desulfurization rate can reach 29.24%and 29.08%,respectively.The fourth-stage desulfurization rate can reach 75.1%and 71.02%,respectively,In the meantime,these two kinds of extractants have good regeneration performance.Then the oxidation system was introduced into the[Bmim]BF₄ and[Bmim]PF₆ionic liquid desulfurization systems,the desulfurization effect of the extraction coupled oxidation on the real fuel oil was investigated.The results show that when the catalyst is phosphomolybdic acid,the desulfurization effect is better.At the same time,the amount of ionic liquid is greatly reduced,the highest desulfurization rate can reach 65.89%and70.75%respectively.At this time,the operating conditions of[Bmim]BF₄system are:ratio of IL to oil is 1:8;ratio of oxygen to oil is 1:16;the oxidation time is 5 h and the oxidation temperature is 50°C.The operating conditions of[Bmim]PF₆ system are:ratio of IL to oil is 1:8;ratio of oxygen to oil is 1:8;oxidation time is 5h;and oxidation temperature is 40°C.Finally,the real fuel oil was replaced by three model fuel oils.The desulfurization effect of[Bmim]BF₄ and[Bmim]PF₆ ionic liquids on different thiophene model oils has been studied.The results show that under the same conditions,the removal rate of dibenzothiophene is the highest,followed by benzothiophene,and the removal rate of thiophene is the lowest.In this paper,the structure of sulfide and ionic liquid and catalytic oxidation mechanism are combined to study the molecular force between sulfide and ionic liquid.Two kinds of desulfurization mechanisms are proposed to explain the above experimental phenomena.