Gasolnhas Uba

Fuel 85 (2006) 1354–1363 www.fuelfirst.com

Deep desulphurization of gasoline and diesel fuels using non-hydrogen consuming techniques
Mohammad Farhat Ali a, Abdullah Al-Malki b, Bassam El-Ali a, Gary Martinie b, Mohammad N. Siddiqui a,*
a

Department of Chemistry, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia b Research and Development Center, Saudi ARAMCO,Dhahran 31311, Saudi Arabia Received 21 September 2005; received in revised form 30 November 2005; accepted 2 December 2005 Available online 10 January 2006

Abstract Desulphurization of FCC gasoline and diesel fuels has been investigated by chemical oxidation of sulphur containing compounds with hydrogen peroxide in the presence of an acid catalyst such as formic acid and acetic acid, followed byextraction of the oxidized compounds using acetonitrile. Oxidative desulphurization (ODS) of diesel fuel was found to be very promising approach for the reduction of up to 92% of sulphur at low temperature (50 8C) and atmospheric pressure. The direct extraction of diesel oil without any oxidation has resulted in about 45% sulphur removal, however such direct extraction also removed other aromatichydrocarbons and affected the yield. The ODS is not successful with FCC gasoline due to the high olefinic content that tends to react with hydrogen peroxide to form epoxides. GC–MS technique was used to identify the sulphones during the oxidation of thiophenes. This study recommends that the oxidation extraction technique be used as an additional process to the hydrodesulphurization to enable therefiners to meet the future environmental sulphur regulations. The conventional hydrodesulphurization can be used to lower the sulphur content to few hundreds ppm. Then, the oxidation/extraction approach needs to be used to go for ultra-deep desulphurization as it may provide better mean and cost effective way in order to meet the future sulphur environmental requirements. q 2006 Elsevier Ltd. Allrights reserved.
Keywords: Deep desulphurization; Diesel; Gasoline; Non-catalytic; Non-hydrogen techniques

1. Introduction The sulphur content in the motor and diesel fuels is continuously reduced by regulations to lower levels. The current specification in Europe and the USA calls for a maximum sulphur content of 50 ppm in gasoline and diesel by 2005 [1,2], and this level will be reduced tobelow 10 ppm by the year 2010 [1]. The current industrial method for removal of sulphur from fuels is hydrodesulphurization (HDS), which requires high temperature and high pressure, making HDS a very costly option for deep desulphurization. Moreover, HDS is not effective for removing hetrocyclic sulphur compounds such as dibenzothiophene (DBT) and its derivatives especially4,6-dimethyldibenzothiophene (4,6-DMDBT). There are many research and development efforts both on the conventional hydrodesulphurization and on alternative methods such as

* Corresponding author. Tel.: C966 3 860 2529; fax: C966 3 860 4277. E-mail address: mnahid@kfupm.edu.sa (M.N. Siddiqui).

0016-2361/$ - see front matter q 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.fuel.2005.12.006

selectiveadsorption, biodesulphurization, oxidation/extraction (oxidative desulphurization) etc. for removing these refractory sulphur compounds from petroleum products [3–12]. Oxidative desulphurization (ODS) has been given much attention as an alternative technology for deep desulphurization. The ODS is basically a two-stage process, oxidation, followed by liquid extraction. In the ODS process, thesulphurcontaining compounds are oxidized using appropriate oxidants to convert these compounds to their corresponding sulphoxides and sulphones. These are preferentially extracted from light oil due to their increased relative polarity [7,9,13,14]. Any unused oxidant that remains in the light oil can be removed by water washing and extracting. The oxidized compounds can be extracted from the light oil by...