Polyethylene glycol as a green solvent for effective extractive desulfurization of liquid fuel at ambient conditions

Abstract

Today there are serious regulations to reduce sulfur content of fuels because the SOx produced during the combustion of fuels containing sulfur compounds make the air polluted and have dangerous environmental impacts. With the aim of replacement of the present volatile, flammable and toxic organic solvents or inefficient, corrosive and expensive ionic liquids (ILs), the polyethylene glycol (PEG) was introduced as a green, effective, non-toxic, non-corrosive and also recyclable molecular solvent for extractive desulfurization (EDS) of benzothiophenic compounds from liquid fuel in this work for the first time. PEG shows excellent EDS and it has the higher extraction efficiency for dibenzothiophene (DBT) (76% within 90s) than those of ILs. Using this extractant, the BDT content was reduced from 512 to 10ppmw (98%) only within three extraction stages, the minimum number of cycles within shortest time reported up to now, and the deep desulfurization was achieved. Effect of some important parameters including initial concentration of sulfur compound, PEG dosage, time and temperature of extraction on the EDS process was investigated. It was fond that extraction performance of PEG is independent to temperature and initial sulfur content, which is an excellent finding for industrialization. The feasibility of PEG for extraction of different thiophenic compounds was observed in the order of dibenzothiophene>benzothiophene>4,6-dimethyldibenzothiopene. Finally, the PEG was reused in several cycles and then it was regenerated by adsorption method. The results of the present work hopefully provide useful information for future industrial application of PEG as an efficient green solvent for the EDS of liquid fuels.