abstract
Oxidative desulfurization (ODS) is a method of removing sulfur from diesel fuel that has the potential to complement or even replace conventional hydrodesulfurization processes in oil refineries. One of the most promising variants of ODS is extractive and catalytic ODS (ECODS) in which the organic sulfur compounds in the liquid fuel are oxidized and extracted in situ from the oil phase into an extractant phase. In this study, the desulfurizalion of model and real diesel fuel has been performed in ECODS systems employing two different types of deep eutectic solvents (DESs), prepared by combining polyethylene glycol (PEG) as hydrogen bond donor with tetrabutylammonium chloride (TBACl) or choline chloride (ChCl) as hydrogen bond acceptor. The ECODS systems were evaluated with the complexes [MoO2Cl2(DMB)(2)] (1) and [MoO2Cl2(DEO)] (2) (DMB - N,N-dimethylbenzamide, DEO = N,N'-diethyloxamide) as catalysts and 30 wt% H2O2 as oxidant. The effects of different reaction conditions, such as the amount of catalyst, H2O2 and DES, and reaction temperature, were investigated. The combination of complex 1 with the DES ChCl/PEG showed the best performance for the removal of dibenzothiophene, 4-methyldibenzothiophene and 4,6-di methyldibenzothiophene from a high-sulfur (3000 ppm) model diesel, allowing a desulfurization efficiency of 99.6% to be attained at 70 degrees C within 2 h. By applying the optimized model diesel ECODS systems to the treatment of a commercial untreated diesel with a sulfur content of 2300 ppm. 82% of sulfur compounds could be eliminated. These promising results indicate that DESs are a viable alternative to ionic liquids as extraction solvents in ECODS processes. (C) 2020 Elsevier B.V. All rights reserved.
keywords
OXIDATIVE DESULFURIZATION; OLEFIN EPOXIDATION; IONIC LIQUIDS; FUELS; GREEN; COMPLEXES; MODEL; DESS
subject category
Chemistry; Physics
authors
Juliao, D; Gomes, AC; Pillinger, M; Lopes, AD; Valenca, R; Ribeiro, JC; Goncalves, IS; Balula, SS
our authors
Ana Catarina Costa Gomes Alves
Assistant Researcher
Diana Julião
PhD Student
Isabel Maria de Sousa Gonçalves
Associate Professoracknowledgements
This work was partly funded through the projects REQUIMTE-LAQV [FCT (Fundacao para a Ciencia e a Tecnologia) Ref. UID/QUI/50006/2019] and CICECO-Aveiro Institute of Materials, UIDB/50011/2020 & UIDP/50011/2020, financed by national funds through the Foundation for Science and Technology/MCTES. The FCT and the European Union are acknowledged for a personal grant to D.J. (SFRH/BD/102783/2014), co-funded by MCTES and the European Social Fund through the program POPH of QREN.