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

Polyethylene glycol (PEG) is not satisfactory for the removal performance of thiophenic sulfurs, e.g., low S-partition coefficient K N (S). The unsatisfactory K N may be due to relatively low content of active O atom on PEG. Modification replacing – OH group with – OCH 3 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 K N than PEG. Its K N for dibenzothiophene (DBT) can reach as high as 3.99. The higher K N 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.