Selective Desulfurization of Model Diesel Fuel by Carbon Nanoparticles as Adsorbent

This work examines the effect of aromatic compounds (naphthalene and 1-methylnaphthalene) on the adsorption of sulfur thiophenic compounds (including benzothiophene, dibenzothiophene, and dimethyldibenzothiophene) from simulated diesel fuel by dispersed carbon nanoparticles (CNPs) in aqueous solution. To evaluate the equilibrium and kinetics of adsorptive desulfurization by synthesized CNPs, two model diesel fuels with 300 ppmw total concentration of sulfur compounds were used in a batch reactor at ambient conditions. The solid CNPs were characterized using FTIR, thermal analysis, elemental analysis, TEM, and surface pH. The equilibrium experimental data were fitted to Langmuir, Freundlich, and Langmuir-Freundlich models to estimate the adsorption parameters. Different equations were applied to fit the kinetics of adsorption and to determine its mechanism. The selectivity for benzothiophene (BT), dibenzothiophene (DBT), and dimethyl dibenzothiophene (DMDBT) adsorption was calculated with naphthalene as reference (NP). Both the adsorption capacity and the selectivity were in the order of BT > DBT > methyl NP approximate to DMDBT > NP. It was found that the rate of adsorption is high and aromatic compounds have no effect on the adsorption kinetics of thiophenic compounds. The results showed that the CNPs can act as a selective adsorbent for the removal of thiophenic carbons in competition with aromatics.