الفهرس 
Aim of the workOnly 14 pages are availabe for public view
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Abstract
Sulfur pollutants in fuel streams are harmful because sulfur oxide (SOx) emitted during combustion of fuels in transportation or oil refineries can interact with water-vapor in the atmosphere, forming acidic rains that are harmful to environmental systems. Environmental protection agency (EPA) strive to set the maximum sulfur content in gasoline to less than 30 ppm, where this ratio was determined in diesel fuel below 15 ppm.
For achieving the lower sulfur content in the HDS process, harsh conditions such as high pressure & temperature, reactors with special specifications and appropriate catalysts are recommended, which lead to the capital cost of HDS process. The alternative and economical process for lowering sulfur content should be taken into accounts such as oxidative desulfurization (ODS), adsorption, extraction, and biodesulfurization. ODS is regarded as a promising strategy as it carried out at mild conditions (usually 40-100°C and 0.1-0.2 MPa). Also, ODS has a high potential for desulfurization of refractory organosulfur substrates. Due to economic and efficient process compared to traditional HDS, ODS considered as a good complementary process to HDS.
In this study, organic sulfur compounds were removed by oxidative desulfurization using environmentally friendly catalysts, where sulfur was removed at moderate conditions (low temperatures, lack of hydrogen gas, short reaction time, and high selectivity of thiophene and benzothiophene derivatives).
polyoxy metalate has received worldwide attention due to its effectiveness in the oxidation reaction of sulfur-containing compounds as well as the high solubility in polar or non-polar solvents, thermodynamic stability and ease control of acid-base properties. However, polyoxy metalate has a low surface area (10 m2/gm). Therefore, immobilizing polyoxy metalate on high
surface area support is recommended, e.g., graphene oxide. The research published in the fields of preparation of graphene oxide and its applications is constantly increasing due to its advantages such as large surface area, thermal stability and as well as its high capability for removing sulfur in different ways.
This study divided into three parts:-
The first part deals with the previously published papers that related various processes in the desulfurization such as hydrodesulfurization and adsorptive and oxidative desulfurization using catalysts, carbon materials ,and polyoxymethyl materials .
Part II: The following catalysts were prepared:
• Preparation and characterization of graphene oxide (GO).
• Preparation of polyoxymolybdate nanoballs{Mo132}.
• Preparation of metal substituted polyoxymolybdate nanoball{Fe30Mo72}.
• Preparation of polyoxomolybdate and metal substituted polyoxymolybdate nanoballs graphene nanocomposite.
Characterization of the prepared materials and composites with conventional techniquesusing such as
a- Infrared Spectroscopy (FTIR) to determine the function groups. b- XRD diffraction to determine the crystallinity of catalysts.
c- Transmission electron microscope (HRTEM) to determine the particle size.
d- N2 adsorption desorption (BET analysis) to determine surface area of synthesized catalysts.
Part III - catalytic activity of prepared catalyst in oxidative desulfurization:
• The efficiency of the prepared materials on Oxidative–desulfurization of petroleum organosulfur compounds(DBT)in dodecane as model oil was studied.
• The reaction condition include (reaction temperature , H2O2 ratio(O/S) molar ratio, catalyst weight, time) was optimized . The results showed that the best conditions for the removal of bhenzoethiophene from the processed oil were (150 minutes, 10 g catalyst for each liter of oil and the ratio of oxygen to sulfur(O/S) = 6 at 60 oC).
• The best condition of the reaction was applied to other organic sulfur compounds such as benzothiophene (BT)and 4.6
dimethyldibenzothiophene(DMDBT). And actual diesel containing 600 ppm sulfur.
• The used catalysts were separated from reaction products by filtration and reused several times without significant reduction in catalytic performance. The study also included the study of kinetics of ODS and the reaction results were indicated that the reaction follows a first order rate kinetic reaction. The values of the reaction rate constant (k) increased with temperature also the activation energy was measured by the Arhnius equation.