Acylation desulfurization of heavy cracking oil as a supplementary oil upgrading pathway

• Thiophenes in real oil are efficiently removed by acylation desulfurization.
• The H/C ratio and boiling point of the ADS oil are higher than those of feed oil.
• Aromatics show a negative impact on the yield and viscosity of the oil products.
• A concept design of desulfurization process for heavy cracking oil is proposed.

Acylation reaction is used to enhance the basicity and polarity of the thiophenes and thus promote their adsorptive removability by Lewis acid, forming an acylation desulfurization (ADS) process for the refractory sulfurs. The ADS performance of six acylating reagents (ARs) was assessed for heavy cracking oil and light oil at 303 K with AlCl3 as the catalyst, and the influence of ADS on the oil quality was also studied. The results show that ADS is efficient to remove the thiophenes, but less efficient for the removal of mercaptans and thioethers in light oil. S-removal rate of 90.9% was achieved for heavy cracking oil with acetyl bromide (AB)-AlCl3 (AB/S = 2/1; AlCl3/S = 5/1) in 0.5 h. The coexistent olefins and aromatics can slightly deteriorate the ADS performance and influence the oil properties. ADS might be used as a promising sulfur separating strategy for the cracking oil.