Desulfurization Of Fuel Oil Via Acylation Reaction

As the specification of oil content in fuel oil becoming more and more stringent and the quality of crude oil becoming worse, the traditional hydrodesulfurization process is facing a big challenge of technology and cost. Therefore researchers extensively investigate non-hydrodesulfurization methods such as adsorption, oxidatation, extraction and so on, to remove the thiophenic sulfur compounds in oil which are refractory ones for hydrodesulfurization. Acylation reaction is used to enhance the basicity and polarity of the thiophenic compounds in model oil and thus promote their adsorptive removal efficiency by Lewis acid, forming an acylation desulfurization (ACDS) process for the refractory sulfurs. In this paper, the ACDS performance of six acylating reagents was assessed for heavy pyrolysis oil and light oil at30℃with AlC13as the catalyst, and the influence of ACDS on the oil quality was also studied. The results show that ACDS is effective for the efficient removal of thiophenic sulfurs. S-removal rate of90.9%was achieved for heavy pyrolysis oil with acetyl bromide (AB)-AlC13(AB/S=2/1; AlCl3/S=5/1) in30min. The coexistent olefins and aromatics can slightly deteriorate the ACDS performance for the heavy pyrolysis oil and influence the oil properties. Meanwhile it is less efficient of ACDS in removing the sulfur compounds which mainly are mercaptans, sulfides and thiophenes in light oil. S-removal rate of54.46%was achieved for light oil with acetyl chloride (AC)-AlC13(AC/S=1/1; AlC13/S=5/1) in30min. By exploring the performance of ACDS in removing propanethiol and dimethyl sulfide in model oil and the influence of cyclehexene on ACDS performance, it is speculated that a large number of olefins in the light oil has a negative impact on the removal of mercaptans, sulfide and thiophenes. ACDS might be used as a promising sulfur separating strategy for the pyrolysis oil and can be combined with hydrogenation, oxidation and other methods to achieve the purpose of efficient and economical deep desulfurization for heavy pyrolysis oil.