Diesel Noc

Electrochemical Desulphurization of Libyan Diesel Fuel by   Dr. Lagili Abouderbala 

University of El-Fateh Faculty of Science

Mr. Jamal  Saidan    [email protected] Libyan Petroleum Institute Research &Development 1

‫تمهيـــــــد‬ ‫الهتمام ‪ ،‬الجودة التى يتمتع بها النفط الليبى وكذلك الموقع الجغرافى الذى‬ ‫تحضى به الجماهيرية الليبية بقربها من السواق العالمية ‪.‬‬ ‫لقد اولت المؤسسة الوطنية للنفط اهتماما بالغا بتحسين جودة النفط الليبى لما لها‬ ‫من مساهمة فى دعم القتصاد الوطني من الجانبين الصناعي والتجاري من جهه‬ ‫والبيئي من جهة اخرى‪ ..‬فقد وضعت الخطط الستراتيجية لتحقيق الهداف‬ ‫المرجوة‪ .‬مما دعى معهد النفط الليبى الى اضافة مبادرة جديدة لتبنى دراسة‬ ‫كهروكيميائية تهدف الى تخفيض نسبة الكبريت فى وقود الديزل ‪.‬‬ ‫وبالرغم من جودة الوقود الليبى ال ان نسبة الكبريت به مازالت تشكل عائقا فى‬ ‫الوصول به الى المستويات العالمية‪ .‬اذ تبلغ نسبة الكبريت فى الوقود المحلى‬ ‫حوالى ‪ 500‬جزء من المليون بينما تبلغ النسبة فى الوقود العالمى حوالى ‪100‬‬ ‫جزء من المليون وتستهدف الدول الصناعية الوصول الى ٍالمعيار العالمى وهو‬ ‫‪ 10‬جزء من المليون بحلول سنة ‪ 2010‬م ‪ .‬ويامل الباحثون بالمعهد الدعم‬ ‫والرعاية لهذا المشروع لتحقيق المستهدف والوصول به الى المعايير الدولية‪.‬‬

Composition Diesel is a very complex  mixture of hydrocarbons  (C12 – C22) the most  important is hexadecane  (cetane) It contains some other  contaminated  species  such as  benzothiophene and  dibenzothiophene . 

3

octane & cetane Gasoline is labeled with its octane number which indicates the ignition performance rating while diesel fuel labeled

95

with its cetane number. 4

Ordinary Techniques Throughout the history of refining, various treatment methods have been used to remove non-hydrocarbons impurities and other constituents that adversely affect the properties of the final products

5



   The most important techniques Hydrotreatment Technique

Hydrodesulfurization ( HDS)  which 

is widely used.

Some other techniques currently 

under developments , for instance:      Oxidative desulfurization (ODS)   Adsorption technique   Liquid extraction.

  Biodesulfurization

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  Despite the efficiency of the  above methods, HDS technology  unable to reduce the sulfur  content to less than 15 ppm.  Furthermore, hydrogen  consumption higher temperature,  higher pressure, larger reactor  volume, and more active  catalysts are unavoidable.  7

Diesel fuel & Environment It is used in most of the world's trucks and buses, and in an increasing number of diesel cars that expected to double in the next twenty years. This will have serious health impacts unless steps are taken to clean up diesel fuel from different impurities. 8

Environment Protection Environmental concerns have driven the need to remove many impurities from diesel fuel. Sulfurcontaining compounds are the most unfavorable species to be removed because of

9

Worried !!!! 10 ppm by 2010 $10 billion

100 ppm by 2010 still 500 ppm in 2008

10

Thiophene

Fuel-containing sulphur which are difficult to remove

Jet range Diesel range Gasoline range

R S

Methyl thiophene

R S

CH3

R

Benzothiophene

S R

Methylbenzothiophene

S

CH3

Dibenzothiophene

R S R

Methyldibenzothiophene

S CH3

R S

4,6 dimethyldibenzothiophene CH3

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CH3

How to Break The Bottleneck? Dibenzothiophene (DBT) and its derivatives, especially 4,6-dimethyl dibenzothiophene (4,6DMDBT) are “bottleneck” problem for deep desulfurization. In order to meet the strictly new regulations, it is necessary to combine different technological options to arrive at an

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Why Electrochemical Technique ? To

overcome

electrochemical

the

bottleneck

technique (EC)

problem, has been

suggested as an alternative technique. It allows a wide potential range to be rapidly scanned for reducible or oxidisable species. This rapidity, together with its variable time scale and good sensitivity, makes it as good selection. 13

Objectives 

Studying the factors effecting the optimum process which include



 Various

concentrations

 Various

scan rate

 Various

temperature

To contribute in designing the appropriate supramolecular host for removing sulfur compounds from diesel fuel.



To invest the approach economically & environmentally.

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Work Plan The first stage of this work will involve the electochemical investigation of the efficiency and tendency of the Supramolecules Dipyridyl to capture sulphur compound which the most unfavourable impurities exist in diesel fuel. 

The second stage will involve the study of removing oxidized sulphur compounds using: 



Hydrophobic-hydrophilic technique (HHT). 

Membrane separation method. 

15 Heavy metal precipitation.

Experimental  Materials:  Model

sulphur ( 4,6-dimethyl

dibenzothiophene) 

local diesel fuel



ferrocene

( Zawyia refinery )

 Acetonitile  Tetra

alkyle amoinum salts 16

Instrumentation & Techniques  CV

& DPV techniques for studying and measurements of 

Modeling compound.



original diesel.



oxidized diesel.



desulfurized diesel.

 X-ray 

fluorescence spectroscopy

For quantative analysis of total sulphur concentration of diesel.

 GC

with FPD detector for organosulfur

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Three electrode system Potentiostat ∆E i

i

W

R

A 18

E

sampling iPa

step height

step width iPc

time

Cyclic voltammetry technique

19

CV’s Parameters

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Simple & Cheap

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Electrochemical Measurements Potentiostat is available in corrosion laboratory of LPI

22

Total Sulfur Analysis

X-ray fluorescence spectroscopy Available in Reaction engineering Laboratory LPI

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Sulfur Compounds Distribution

Flam photometric Detector GC FPD available in GC Laboratory LPI

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Host –Guest Interaction The project is based on the concept of the non covalent hostguest interaction which in turn is based on the molecular recognition 25

Host – Guest Interaction NH N Fc Fc

+ N

R

HN

CH4

R

S

S CH3

CH3

CH3 N

Fc

N

Fc

NH

HN

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CV’s For Free & Bound

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Host - Guest Interaction HN Fe

N

Fe

G N

Fe

NH

N

HN

G Fe

Fe

N HN

NH N

G

N

NH Fe

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Why Ferrocene?? Fc Fe

HN Fc

NH HN

N

A1

• Due to neutrality, it has no inherent  electrostatic attraction with either  anions or cations •   It has low binding constant •  It can be switched – on by  oxidation  •  Ferrocenium can be exploit to    recognise anions 29

Preparation of the pyridyl Fc

NH2

O

+

HN

Fe

N NH

Fc

Fc

HN

2

NH

Br

+

Fc

NH

HN

N

N

Br

30

Fc

HN

NH

Fc

Fc

Fc

HN

Fc

NH Fc

N

N

HN

N

N

N

NH N

o-A2

p-A2

m-A2

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Calculations

The experimental results will be subjected to the following calculations 32

Data Analysis • Statistical treatment • Diffusion coefficient determination • Binding constant determination 33

   Randles­Sevcik equation:

i p = 2.69 x10 n 5

3/ 2

AD ν 1/ 2

1/ 2

Cο

Where n   is the scan rate in V/s ip  is the current, A n  is the number of electrons F  is the Faraday constant 96485  C mol­1 A  is the electrode surface area, cm2 Do is the Diffusion coefficient, cm2s­1 Cx  is the concentration, mol dm­3 34

The hydrodynamic radius of the subjected species can be calculated using StokesEinstein equation:

kT r= 6πηD Where r refers to hydrodynamic radius k refers to Boltzmann constant other parameters have its convenient 35

RT RT E1/ 2( complex ) − E1/ 2( free ) = − 2.303log(K f ) − 2.303[ qlog(c G )] nF nF

E½(bound)- E½(free)/ V

Variation of the 



  

potential increment as a function of log (c) for estimating the binding constants

Log c / mol dm-3

of the species in question.

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Electrochemical studies of desulphurization Of Libyan diesel fuel

Data analysis

Interpretation of experimental data

Electrochemical techniques CV& DPV

Monitoring the current response at Various supporting electrolytes Various concentration Various temperature Various scan rate

Plan strategy and Research aims

Computer modeling

In collaboration With other research group

Determination of electrochemical properties particularly the factors affecting the redoxing of sulphur In diesel conclusion

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Acknowledgements The authors wish to thank  Dr.

Mohammed El-Garni  Dr. Salem Al-Debbah  Mr. Omar Ergahi  Mr. Mohieddin Jallol  LPI institute  El-Fateh university

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