Adsorptive desulfurization using different passivated carbon nanoparticles by PEG-200

• This work presents the mechanistic study of sulfur adsorption process by carbon nanoparticles (CNPs).
• CNPs have been prepared by different methods and applied for removal of sulfur from liquid fuel.
• The presence of PEG 200 for preparation of CNPs which are efficient in desulfurization is crucial.
• PEG decomposition at high temperature, introduces functional groups on the CNPs surface and activate sulfur adsorption.

Carbon nanoparticles dispersed in aqueous phase (CNPs) were synthesized using different poly(ethylene glycol) (PEG 200) assistant solution methods including microwave pyrolysis and alkali-assisted heating, ultrasonication, and refluxing. The CNPs (< 5 nm) were used for the selective removal of sulfur thiophenic compounds (benzothiophene (BT), dibenzothiophene (DBT) and dimethyldibenzothiophene (DMDBT)) from liquid model fuels including aromatic compounds (naphthalene (NP) and 1-methylnaphthalene (MNP)). The presence of PEG in the preparation procedure of CNP was crucial and adsorption capability was related to the passivation by PEG. The decomposition of PEG at high temperature introduced more acidic functional groups on the carbon framework and also promoted the formation of porous CNP nanostructures because of hydrophobic PEG aggregations. Adsorption experiments showed the order for CNPs with different method as: microwave irradiation > heating > refluxing > ultrasonication. The highest efficiency of CNPs by microwave-assisted technique for sulfur removal was examined due to the higher decomposition of PEG and more porosity of CNP nanostructures which were produced at higher temperature. Moreover the CNPs were regenerable by a solvent-washing process. This study showed that passivated CNPs are very effective for rapid desulfurization of liquid fuels, operating at ambient conditions with the ease of separation and regeneration.