Performance and mechanism for extractive desulfurization of fuel oil using modified polyethylene glycol

[Display omitted] •Modification that replaces –OH group of PEG with –OCH3 group can significantly improve desulfurization performance.•S-partition coefficient [KN, (μgS·gEx−1)/(μgS·gOil−1)] of NHD can reach as high as 3.99–4.40 for DBT at room temperature.•Selectivity [KN (DBT)/KN (toluene)] of mPEG can be more than 5.50 at room temperature. Polyethylene glycol (PEG) is not satisfactory for the removal performance of thiophenic sulfurs, e.g., low S-partition coefficient KN (S). The unsatisfactory KN may be due to relatively low content of active O atom on PEG. Modification replacing –OH group with –OCH3 group can produce modified PEGs that have the higher active O-content. Polyethylene glycol dimethyl ether, which was commonly known as NHD, showed the higher KN than PEG. Its KN for dibenzothiophene (DBT) can reach as high as 3.99. The higher KN was dominantly ascribed to the contribution of the active O atom: (1) H-bonding with DBT; (2) group similarity between C-O-C and C-S-C. Further, methoxy polyethylene glycol (mPEG) showed the best selectivity for DBT to toluene, compared with NHD and PEG. The best selectivity of mPEG may be attributed to its higher active O-content than PEG’s and its stronger polarity than NHD’s. Moreover, NHD and mPEG can be regenerated and recycled for several times without significantly decreasing the desulfurization performance.